What are the common properties of Group 1 elements in the periodic table?

Group 1 elements, also known as alkali metals, include lithium, sodium, potassium, rubidium, cesium, and francium. They are characterized by having a single electron in their outermost shell, which makes them highly reactive. These metals are soft, have low melting points, and are good conductors of electricity. They react vigorously with water to form alkaline hydroxides and hydrogen gas.

Why are Group 1 elements called alkali metals?

Group 1 elements are called alkali metals because they form alkaline solutions when they react with water. The reaction produces a hydroxide of the metal, which is a strong base or alkali. For example, when sodium reacts with water, it forms sodium hydroxide, which is a typical alkali.

How does the reactivity of Group 1 elements change down the group?

The reactivity of Group 1 elements increases as you move down the group in the periodic table. This is because the outer electron becomes more easily lost due to the increasing atomic size and the decreasing attraction between the nucleus and the outer electron. As a result, elements like cesium and francium are more reactive than lithium and sodium.

What are some common uses of Group 1 elements?

Group 1 elements have various applications due to their unique properties. For example, lithium is used in rechargeable batteries, sodium is used in street lighting and as a coolant in nuclear reactors, and potassium is essential for plant growth and is used in fertilizers. These applications take advantage of their reactivity and conductivity.

How are Group 1 elements stored and handled safely in the laboratory?

Due to their high reactivity, especially with water and air, Group 1 elements must be stored under oil to prevent reactions with moisture and oxygen. In the laboratory, they should be handled with care using appropriate safety equipment, such as gloves and goggles, and in a controlled environment to prevent accidental reactions.

Why is "Writing the wrong product for Group 1 + water (e.g. metal oxide instead of hydroxide)" a common mistake in Group 1?

Why it happens: Confusing the reaction of the metal with water (gives MOH) with the reaction of the metal with oxygen (gives M₂O). How to avoid it: REMEMBER: Group 1 + WATER → metal HYDROXIDE + hydrogen (2M + 2H₂O → 2MOH + H₂). Group 1 + OXYGEN → metal OXIDE (4M + O₂ → 2M₂O). Different reactants → different products. Source: 4CH1 Examiner Reports 2022-2024

Why is "Stating that reactivity DECREASES down Group 1 (confusing with Group 7)" a common mistake in Group 1?

Why it happens: Mixing up Group 1 and Group 7 trends — both have a 'down-the-group' trend but in opposite directions. How to avoid it: Group 1 LOSES an electron — easier with more shells → reactivity INCREASES down. Group 7 GAINS an electron — harder with more shells → reactivity DECREASES down. Remember: 'lose easier' vs 'gain harder'.

Why is "Saying 'nuclear charge decreases down the group' to explain reactivity" a common mistake in Group 1?

Why it happens: Thinking that less attraction means less charge. How to avoid it: Nuclear charge INCREASES down the group (more protons). But the INCREASE in atomic radius and shielding OUTWEIGHS the rise in nuclear charge → net attraction on the outer electron DECREASES. Use 'distance + shielding outweigh nuclear charge'. Source: 4CH1 Examiner Reports 2023-2024

Why is "Writing 'Na + H₂O → NaOH + H' (forgetting the diatomic hydrogen molecule)" a common mistake in Group 1?

Why it happens: Forgetting that hydrogen gas is H₂, not H. How to avoid it: Hydrogen GAS is ALWAYS diatomic H₂. Balanced equation: 2Na + 2H₂O → 2NaOH + H₂ (two Na to make one H₂). Same for Li, K, Rb, Cs — always use H₂.

Why is "Writing 'yellow' as the flame colour of lithium" a common mistake in Group 1?

Why it happens: Confusing Li with Na — sodium gives the bright yellow that's most familiar. How to avoid it: Li = CRIMSON RED. Na = ORANGE-YELLOW (the brightest, most familiar). K = LILAC. Memorise: 'Lily Red, Nancy Yellow, Kate Lilac'. Source: 4CH1 Examiner Reports 2022-2024

Why is "Saying 'more energy levels' instead of 'more inner shells' / 'more shielding'" a common mistake in Group 1?

Why it happens: Loose terminology — energy levels and shells are related but the mark scheme expects the link to shielding. How to avoid it: Mark scheme rewards: 'more inner electron shells → more SHIELDING → weaker attraction'. Always link more shells to SHIELDING of the outer electron. Source: 4CH1 Examiner Reports 2022-2024

Inorganic ChemistryPearson Edexcel IGCSE Chemistry 4CH1 Higher

Group 1

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Group 1 — Alkali Metals — Pearson Edexcel International GCSE Chemistry 4CH1 Study Notes (2026 onwards, Spec Issue 4)

Properties, reactions and reactivity trends of the Group 1 alkali metals (Li, Na, K, Rb, Cs, Fr). Each atom has ONE outer-shell electron lost easily to form a +1 ion, so all are highly reactive. Reaction with water produces an alkaline hydroxide MOH + hydrogen gas. Reactivity INCREASES down the group as the outer electron sits further from the nucleus and is more shielded — making it easier to lose.

What you’ll learn

Mapped to the Pearson Edexcel IGCSE 4CH1 syllabus (2026 onwards).

2.1 — Understand that the Group 1 elements (alkali metals) all have ONE outer-shell electron.
2.2 — Describe the physical properties of the alkali metals (soft, low density, low mp/bp, shiny when freshly cut).
2.3 — Describe the reactions of lithium, sodium and potassium with water, including word and balanced symbol equations.
2.4 — Explain the trend in reactivity of the Group 1 elements down the group in terms of electronic configuration and atomic radius (and shielding).
2.5 — Predict the properties of other elements in Group 1 (notably rubidium, caesium, francium) given the pattern of the known elements.

Overview and physical properties (spec 2.1, 2.2)

Soft, low-density metals with one outer-shell electron — very different from typical metals like iron or copper.

Who is in Group 1?

The first column of the periodic table contains the alkali metals: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr). (Hydrogen is sometimes placed in Group 1 in the periodic table but is NOT an alkali metal — it behaves quite differently.)

All Group 1 atoms have one outer-shell (valence) electron:

Li: 2,1
Na: 2,8,1
K: 2,8,8,1
Rb: 2,8,18,8,1
Cs: 2,8,18,18,8,1
Fr: 2,8,18,32,18,8,1

This single outer electron is at the heart of all Group 1 chemistry — they react by LOSING it to form a +1 ion (e.g. Na → Na⁺ + e⁻).

Every Group 1 atom has one outer-shell electron — it sits further out as you go down the group.

Physical properties of Group 1 metals.

Soft. All alkali metals are soft enough to cut with a knife — Na and K cut like cheese; Cs is almost like butter. Compare with hard metals like iron and copper.
Low density. Lithium (0.53 g/cm³), sodium (0.97), potassium (0.86) all FLOAT on water (density 1.00 g/cm³). Caesium is denser (1.93) but still much less than iron (7.87) or copper (8.96). Reason: the atoms are large and the metallic bonding is weak.
Low melting and boiling points. Mp/bp values (°C):

Element Mp Bp
Li 181 1342
Na 98 883
K 64 759
Rb 39 688
Cs 28 671

Compare with iron (mp 1538 °C). Group 1 metals have WEAK metallic bonding — only one delocalised electron per atom contributes to the 'sea of electrons'.
Shiny when freshly cut. A newly cut surface looks bright silver but TARNISHES rapidly (within seconds) as it reacts with oxygen and water vapour in the air to form a dull oxide/hydroxide coating.
Good conductors of heat and electricity. Like all metals, they have a sea of mobile delocalised electrons that carry charge and energy.

Element	Mp	Bp
Li	181	1342
Na	98	883
K	64	759
Rb	39	688
Cs	28	671

Storage. Because they tarnish so quickly and react violently with water, alkali metals are stored UNDER OIL (paraffin oil). The oil keeps both air and water from the metal surface. Pieces are handled with tweezers and cut with a knife on a dry tile.

Group 1 atoms have ONE outer-shell electron — basis of all their chemistry.
Soft, low density (Li/Na/K float), low mp/bp, shiny then tarnish.
Stored under oil to prevent reaction with O₂ and water vapour.

Reactions with water (spec 2.3)

All produce metal hydroxide MOH (alkaline) + hydrogen gas. Vigour increases down the group.

Group 1 metals react with water to produce an alkaline metal hydroxide and hydrogen gas. The general equation:

$2\text{M(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{MOH(aq)} + \text{H}_2\text{(g)}$

The reaction is highly exothermic — heat released raises the local temperature; can ignite the hydrogen.

Lithium.

$2\text{Li(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{LiOH(aq)} + \text{H}_2\text{(g)}$

Observations: Li floats, fizzes steadily (bubbles of H₂), gradually dissolves over a few minutes. NO ignition — the reaction is too gentle to heat the H₂ enough.

Sodium.

$2\text{Na(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(aq)} + \text{H}_2\text{(g)}$

Observations: Na floats, fizzes vigorously, MELTS into a silvery ball (low mp 98 °C; exothermic reaction provides enough heat). The molten ball rolls rapidly across the surface, propelled by the H₂ gas. Sometimes the H₂ ignites with a yellow-orange flame, ending in a small 'pop'.

Potassium.

$2\text{K(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{KOH(aq)} + \text{H}_2\text{(g)}$

Observations: K floats, fizzes very violently, melts immediately and IGNITES — burning with a LILAC flame (the characteristic colour of K⁺ ions). The piece may rush across the surface and end in a small explosion. Reaction over in 10-20 seconds.

Rubidium and caesium react EXPLOSIVELY with water — dangerous to demonstrate without a protective enclosure. Both ignite immediately on contact.

Detecting the alkali formed. The MOH product is a STRONG ALKALI (pH 13-14 in solution):

Turns red litmus paper BLUE.
Turns universal indicator PURPLE/dark blue.
Reacts with acids to give a salt + water (neutralisation).

If you drop sodium into water that already contains a few drops of universal indicator, the indicator turns purple in a 'cloud' around the metal as NaOH dissolves.

Detecting the hydrogen. Hold a lighted splint near the H₂ being evolved — it produces a 'SQUEAKY POP' (a small explosion as H₂ burns with O₂ in air).

All Group 1 + water → MOH(aq) + H₂(g) (alkaline hydroxide + hydrogen).
Li: gentle fizz. Na: melts + fizzes vigorously. K: ignites + lilac flame.
Rb / Cs: explosive — dangerous demonstrations only.
Test for alkali (universal indicator → purple); test for H₂ (squeaky pop).

See the full worked example for group 1 →

Why reactivity INCREASES down Group 1 (spec 2.4)

Outer electron is further from nucleus AND more shielded → easier to lose → more reactive.

Reactivity in Group 1 is judged by how readily the atom loses its single outer-shell electron to form M⁺. Going down the group from Li to Cs, three structural changes occur — and together they make the electron easier to lose.

1. Atomic radius INCREASES. Each successive element has an extra electron shell:

Li: 2 shells (outer in shell 2)
Na: 3 shells (outer in shell 3)
K: 4 shells (outer in shell 4)
Rb: 5 shells (outer in shell 5)
Cs: 6 shells (outer in shell 6)

The outer electron is therefore FURTHER from the nucleus. Atomic radii: Li 152 pm → Cs 265 pm — almost double.

2. Shielding INCREASES. The inner filled shells partially shield the outer electron from the positive nuclear charge — they act as a 'screen'. Going down the group, MORE inner shells means MORE shielding:

Li: 1 inner shell shields the outer electron.
Na: 2 inner shells shield.
K: 3 inner shells.
Cs: 5 inner shells.

3. Nuclear charge INCREASES (but is outweighed). Each element has more protons (Li 3p → Cs 55p). You might think this would make the outer electron HARDER to remove. But the increases in atomic radius and shielding more than offset this — the EFFECTIVE attraction on the outer electron actually DECREASES.

Net effect. Going down the group, the attraction between the nucleus and the outer electron WEAKENS. So the outer electron is HELD LESS TIGHTLY and LOST MORE EASILY → reactivity INCREASES.

Down the group the outer electron is further out and more shielded, so it is lost more easily.

This is shown clearly by the FIRST IONISATION ENERGIES (energy needed to remove the outer electron):

Element	1st IE (kJ/mol)
Li	520
Na	496
K	419
Rb	403
Cs	376

Lower IE → easier to lose outer electron → more reactive.

Linking to observed reactivity with water. As we saw, Li reacts gently; Na vigorously; K ignites. The trend in violence MATCHES the trend in first ionisation energy. The most reactive Group 1 metals (Cs, Fr) are extremely vigorous, sometimes explosive.

The opposite trend in Group 7. Note the contrast: Group 7 reactivity DECREASES down the group. Why? Because Group 7 reacts by GAINING an electron (not losing one) → the trend in 'ease of gaining an electron' goes the OTHER way down the group. Same atomic-structure reasoning, opposite reactive process.

Atomic radius increases down the group (more shells).
Shielding by inner shells increases → effective attraction weakens.
Outer electron is easier to lose → reactivity INCREASES.
Contrast: Group 7 GAINS electrons → reactivity DECREASES down.

See the full worked example for group 1 →

Reactions with oxygen and other patterns

Group 1 + O₂ → M₂O (oxide); Group 1 + halogen → MX (ionic halide).

Beyond the reaction with water, Group 1 metals show predictable behaviour with other substances.

Reaction with oxygen. Group 1 metals burn in air (or oxygen) with characteristic flame colours, forming a metal OXIDE:

$4\text{Li(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Li}_2\text{O(s)} \text{ (red flame)}$ $4\text{Na(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Na}_2\text{O(s)} \text{ (orange-yellow flame)}$ $4\text{K(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{K}_2\text{O(s)} \text{ (lilac flame)}$

The oxides are WHITE solids and react with water to form the same alkali as before:

$\text{Na}_2\text{O(s)} + \text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(aq)}$

Note: In practice, Na also forms Na₂O₂ (peroxide) and K forms KO₂ (superoxide) under excess O₂, but Edexcel 4CH1 only requires the simple oxide M₂O.

Reaction with halogens. Group 1 metals react vigorously with Group 7 elements (halogens) to form IONIC halides:

$2\text{Na(s)} + \text{Cl}_2\text{(g)} \rightarrow 2\text{NaCl(s)}$ $2\text{K(s)} + \text{Br}_2\text{(l)} \rightarrow 2\text{KBr(s)}$

The reactions are highly exothermic. The metal loses 1 electron; the halogen gains 1 electron. The resulting compound is a typical IONIC SALT — white crystalline solid, soluble in water, high mp, conducts when molten or dissolved.

Flame test colours. The characteristic colours imparted by Group 1 ions in a flame are used for identification:

Ion	Flame colour
Li⁺	Crimson red
Na⁺	Orange-yellow / 'golden'
K⁺	Lilac (pale purple)
Rb⁺	Red-violet
Cs⁺	Blue

Method for flame test. Use a clean nichrome (or platinum) wire — dip in concentrated HCl, then into the solid sample. Hold in the HOTTEST part of a BLUE Bunsen flame (air-hole fully open). The HCl cleans the wire and volatilises the metal ion; the heat excites electrons in the ion, which emit characteristic colours as they return to the ground state. Always clean the wire between samples to avoid contamination — even traces of Na drown out K's lilac with strong yellow (cobalt-blue glass can filter out the yellow to confirm K).

Group 1 + O₂ → metal oxide M₂O (white solid, reacts with water to give MOH).
Group 1 + halogens → ionic salt MX (e.g. NaCl, KBr).
Flame test colours: Li red, Na yellow, K lilac, Rb red-violet, Cs blue.

See the full worked example for group 1 →

Predicting properties of francium (spec 2.5)

Extrapolate from observed trends — most reactive Group 1 metal; very low mp; explosive with water.

Francium (Fr) is the heaviest Group 1 metal. It is RADIOACTIVE — the most stable isotope (²²³Fr) has a half-life of only ~22 minutes. The total amount of Fr on Earth at any given time is estimated at less than 30 g, so bulk samples have never been studied. We predict its properties by EXTRAPOLATING from the observed trends in Li → Cs.

Predicted property 1 — Extreme reactivity with water.

Continuing the trend Li < Na < K < Rb < Cs, francium would react EVEN MORE VIOLENTLY than caesium — almost certainly explosively. Equation predicted:

$2\text{Fr(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{FrOH(aq)} + \text{H}_2\text{(g)}$

Reason: Fr's outer electron sits in the 7th shell, furthest from the nucleus, with the most inner-shell shielding of any Group 1 element. Lowest 1st ionisation energy → outermost electron most easily lost.

Predicted property 2 — Very low melting point.

Mp trend: Li 181 → Cs 28 °C. Extrapolation suggests Fr might melt at ~20-25 °C — potentially a LIQUID at warm room temperature. Reason: weak metallic bonding (only one outer electron contributes to the electron sea), and the largest atomic radius gives the weakest bonds.

Predicted property 3 — Soft, low density.

Like Cs but even softer. Density predicted ~2.0-2.5 g/cm³ — still low for a metal, continuing the trend Cs 1.93.

Predicted property 4 — Forms strongly alkaline FrOH.

By extension, Fr would form a STRONG alkali FrOH in water — more alkaline than KOH or CsOH. Reacts with acids to form a salt + water.

Predicted property 5 — Brilliant flame test colour.

Extrapolating from the colour trend, francium's flame test would be expected to be a redder/more orange colour relative to Cs's blue — though it has never been measured in bulk quantity.

Limitation — radioactivity. Francium isotopes decay by alpha or beta emission. Bulk samples are NOT made. Predictions are based on TRENDS — never verified by experiment on macroscopic amounts.

Strategy for exam questions about Fr. When asked to predict properties of Fr, always:

State the relevant Group 1 trend (reactivity, mp, density, etc.).
Apply the trend to Fr (more reactive, lower mp, etc.).
Justify briefly with atomic structure (more shells, more shielding, outer e⁻ further out).

Examiners reward atomic-structure REASONING, not just 'because it's at the bottom'.

Fr is radioactive — predictions based on extrapolating trends, never measured.
Most reactive Group 1 metal — reacts explosively with water (predicted).
Predicted mp ~20-25 °C — possibly liquid at warm room temperature.
Always justify predictions in terms of atomic radius + shielding.

See the full worked example for group 1 →

How it’s examined

Group 1 is a high-frequency Paper 1 (4CH1/1C) topic — worth 5-10 marks per session. Typical items: (a) write balanced equations for Group 1 metal + water (1-3 marks); (b) describe observations of a named alkali metal with water (3-5 marks); (c) explain the reactivity TREND down the group in terms of atomic structure (4-6 marks); (d) predict the properties of Rb, Cs or Fr (3-5 marks); (e) flame test identification (3-4 marks). Paper 2 (4CH1/2C) extension items include comparing Group 1 with Group 7 trends (5-6 marks) and explaining why francium is the most reactive (atomic structure reasoning).

Sources: Pearson Edexcel International GCSE Chemistry 4CH1 specification — Issue 4, September 2024 (valid for 2026 onwards); Pearson Edexcel 4CH1 Examiner Reports 2022-2024; 4CH1/1C May/Jun 2024 question paper and mark scheme; 4CH1/1C January 2024 question paper and mark scheme; 4CH1/1CR January 2024 question paper and mark scheme; 4CH1/2C May/Jun 2024 question paper and mark scheme; 4CH1/2C January 2024 question paper and mark scheme. Last reviewed 2026-05-12.

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Step-by-step worked examples — Group 1

Step-by-step solutions to past-paper-style questions on group 1, written exactly the way a tutor would explain them at the board.

1Sodium added to water — observations + equation (5 marks, Paper 1)
Core• Adapted from 4CH1/1C Jan 2024 Q3• group 1, reaction with water, spec-2.2, spec-2.3
Question
A small piece of sodium (about the size of a pea) is added to a trough of water containing a few drops of universal indicator. Describe FOUR observations you would expect to see and write a balanced equation for the reaction. (5 marks)
Step-by-step solution
1. Step 1
  Float (1 A). Sodium has a low density (~0.97 g/cm³), less than water (~1.00 g/cm³), so it floats on the surface.
2. Step 2
  Melts into a ball / fizzes (1 A). The reaction is exothermic. Heat released is enough to melt the small piece of sodium (mp ≈ 98 °C, low for a metal). It forms a silvery molten ball that moves around the surface. Hydrogen gas evolved makes it fizz.
3. Step 3
  Solution turns purple (1 A). Sodium hydroxide (NaOH) is formed and dissolves in the water. NaOH is a strong alkali (pH > 11), so the universal indicator turns from green to purple/dark blue.
4. Step 4
  Sodium disappears / pop heard (1 A). Sodium is gradually consumed. If a lighted splint is held nearby, the hydrogen ignites with a SQUEAKY POP.
5. Step 5
  Balanced equation (1 B). Sodium + water → sodium hydroxide + hydrogen.
  $2\text{Na(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(aq)} + \text{H}_2\text{(g)}$
Answer
Observations: (1) floats; (2) melts into a ball / fizzes; (3) moves on surface; (4) indicator turns purple (alkaline NaOH formed); H₂ pops if lit. Equation: 2Na + 2H₂O → 2NaOH + H₂.
Examiner tip
Edexcel 5-mark mark scheme: 1 mark per valid observation (max 4) + 1 mark for a fully balanced equation with correct state symbols (qcf). Most-frequent error: writing 'Na₂O' or just 'NaO' as the product. The product of Group 1 + water is ALWAYS the metal hydroxide MOH plus H₂.
2Explain the trend in reactivity down Group 1 (5 marks, Paper 1)
Core• Adapted from 4CH1/1C May/Jun 2024 Q5• group 1, reactivity trend, atomic structure, spec-2.4
Question
Reactivity of the Group 1 metals INCREASES going down the group from Li to Cs. Explain this trend in terms of atomic structure and electron loss. (5 marks)
Step-by-step solution
1. Step 1
  Group 1 atoms have ONE outer-shell electron (1 M). All alkali metals react by LOSING this outer electron to form a +1 ion (e.g. Na → Na⁺ + e⁻). So 'more reactive' means 'loses outer electron more easily'.
2. Step 2
  Atomic radius INCREASES down the group (1 A). Each successive element has an EXTRA electron shell (Li: 2 shells; Na: 3; K: 4; Rb: 5; Cs: 6). The outer electron is therefore FURTHER from the nucleus.
3. Step 3
  Increased shielding by inner electrons (1 A). The inner filled shells partially shield the outer electron from the positive nuclear charge. Going down the group there are MORE inner shells → greater shielding effect.
4. Step 4
  Weaker electrostatic attraction (1 B). Because of the greater distance (atomic radius) AND greater shielding, the attraction between the positive nucleus and the outer electron WEAKENS down the group. (Even though nuclear charge increases, the distance + shielding effects dominate.)
5. Step 5
  Easier to lose outer electron → more reactive (1 B). The outer electron is held less tightly, so it is more easily lost when reacting with water or oxygen. Hence reactivity INCREASES down the group: Li < Na < K < Rb < Cs.
Answer
Atoms have one outer-shell electron, lost in reactions to form M⁺. Going down the group: atomic radius increases (more shells), shielding by inner electrons increases, so attraction between nucleus and outer electron decreases → electron lost more easily → more reactive.
Examiner tip
Edexcel 5-mark mark scheme: 1 for stating the outer electron is lost; 1 for atomic radius (more shells); 1 for shielding by inner electrons; 1 for weaker attraction between nucleus and outer e⁻; 1 for 'easier to lose e⁻ so more reactive'. DON'T just say 'more energy levels' — examiners want 'more inner shells → more shielding'. AVOID saying nuclear charge decreases — it INCREASES, but distance/shielding dominate.
3Potassium with water — equation and observations (3 marks)
Core• Adapted from 4CH1/1CR Jan 2024 Q4• group 1, potassium, balanced equation, spec-2.3
Question
A small piece of potassium is added to water. Describe what would be observed, write a balanced symbol equation including state symbols, and identify the flame colour seen during the reaction. (3 marks)
Step-by-step solution
1. Step 1
  Observations (1 A). Potassium floats, fizzes very violently, melts into a ball, moves rapidly across the surface. The reaction is so exothermic that the hydrogen gas produced IGNITES — burning with a LILAC flame. The piece is consumed quickly; a small explosive pop can be heard at the end.
2. Step 2
  Balanced equation with state symbols (1 A). Potassium + water → potassium hydroxide + hydrogen.
  $2\text{K(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{KOH(aq)} + \text{H}_2\text{(g)}$
3. Step 3
  Flame colour (1 B). Potassium produces a characteristic LILAC (pale purple) flame. This colour is used in flame tests to identify K⁺ ions.
Answer
Floats, fizzes violently, ignites with a LILAC flame, melts into a ball, moves on the surface. Equation: 2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g). Flame colour: lilac.
Examiner tip
Edexcel 3-mark mark scheme: 1 for observation including 'ignites/lilac flame'; 1 for the balanced equation; 1 for correct state symbols. Common error: writing KO or K₂O — the product is KOH. Don't confuse Li (crimson red) with K (lilac).
4Predict the properties of francium (5 marks, Paper 1)
Extended• Adapted from 4CH1/1C May/Jun 2024 Q7• group 1, francium, prediction, trend, spec-2.4, spec-2.5
Question
Francium (Fr) is the heaviest member of Group 1. Using your knowledge of the trends in Group 1, predict THREE properties of francium and explain your predictions in terms of atomic structure. (5 marks)
Step-by-step solution
1. Step 1
  Identify the trends (1 M). Reactivity, atomic radius, density all change down Group 1. Use these to predict Fr's behaviour.
2. Step 2
  Prediction 1 — extremely reactive (1 A). Fr would react with water EXPLOSIVELY, even more violently than caesium. The reaction would produce francium hydroxide (FrOH) and hydrogen gas: 2Fr + 2H₂O → 2FrOH + H₂. Reason: Fr's outer electron is in the highest shell (n = 7), furthest from nucleus, with most inner-shell shielding → most easily lost.
3. Step 3
  Prediction 2 — low melting point (1 A). Mp would be even lower than Cs (~28 °C). Down Group 1, the metallic bonding gets weaker because the outer electrons are further from the nucleus and less strongly attracted into the 'sea'. So Fr would likely be a LIQUID at warm room temperature.
4. Step 4
  Prediction 3 — high density / soft (1 A). Density INCREASES generally down Group 1 (Cs ~1.93 g/cm³), so Fr would be denser than caesium — but still relatively low for a metal. It would still be soft enough to cut with a knife.
5. Step 5
  Why we can't test (1 B). Francium is the only Group 1 metal that is RADIOACTIVE and extremely rare (longest-lived isotope ²²³Fr has half-life ~22 minutes). Its predicted properties are extrapolated from the periodic trends — never measured experimentally on bulk Fr.
Answer
Three predictions: (1) reacts explosively with water (more vigorous than Cs) — outer e⁻ furthest from nucleus + most shielding → easiest to lose; (2) low mp / possibly liquid at room temperature — weak metallic bonding; (3) density slightly higher than Cs — trend of increasing density down the group. Note: Fr is radioactive and rare, so predictions only.
Examiner tip
Edexcel 5-mark mark scheme: 3 marks for valid predictions (any from: violent reaction with water, low mp, soft, high density, alkaline hydroxide, characteristic flame colour); 2 marks for linking to atomic structure (more shells / increased shielding / outer e⁻ further from nucleus). Marks NOT awarded for vague 'more reactive' without atomic-structure reasoning.
5Identify Group 1 ions using flame tests (5 marks, Paper 1)
Core• Adapted from 4CH1/1C May/Jun 2024 Q4 (qualitative analysis)• group 1, flame test, qualitative analysis, spec-2.5
Question
A student is given three unlabelled white solids: lithium chloride, sodium chloride and potassium chloride. Describe the procedure for a flame test, state the expected colour for each compound, and explain the purpose of cleaning the wire between tests. (5 marks)
Step-by-step solution
1. Step 1
  Apparatus and procedure (1 M). Use a clean nichrome (or platinum) wire mounted on a glass-rod holder. Dip the wire into concentrated hydrochloric acid (HCl), then into the white solid so a tiny amount sticks to the wet wire. Hold the wire in the HOTTEST part of a BLUE Bunsen flame (roaring flame, air-hole open).
2. Step 2
  Lithium → crimson red flame (1 A). Heated Li⁺ ions in the flame emit a characteristic CRIMSON RED colour.
3. Step 3
  Sodium → orange-yellow / golden flame (1 A). Na⁺ ions give a strong, persistent yellow-orange colour (the same as sodium streetlights).
4. Step 4
  Potassium → lilac flame (1 A). K⁺ ions give a pale purple/lilac colour. This colour is sometimes obscured by traces of sodium; view through blue cobalt glass to filter out yellow Na light and confirm K is present.
5. Step 5
  Why clean the wire between tests (1 B). A clean wire is essential to avoid CONTAMINATION from the previous sample. Even a trace of Na on a wire used for K would mask the lilac with bright yellow. Clean by repeatedly dipping in conc. HCl + heating in the flame until no colour shows.
Answer
Procedure: clean nichrome wire dipped in conc HCl, then in solid, hold in blue Bunsen flame. Li → crimson red; Na → orange-yellow; K → lilac. Clean wire between tests to prevent contamination — even trace Na masks K's lilac with strong yellow.
Examiner tip
Edexcel 5-mark mark scheme: 1 for procedure (clean wire, conc HCl, blue flame); 1 each for Li/Na/K correct colour; 1 for explaining contamination. Examiners frequently award full marks for correct colours even with brief procedure — but a full procedure can earn extra detail marks. AVOID writing 'yellow' for Li (it's red/crimson) — a common error.

Model Answers — Group 1

High-scoring sample answers for group 1 on the Pearson Edexcel IGCSE 4CH1 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.

Question 1

4CH1/1C-style — physical properties of Group 16 marks

Describe FOUR physical properties of the Group 1 metals AND explain how each property differs from typical (transition) metals like iron or copper. (6 marks)

Model answer

Group 1 metals (Li, Na, K, Rb, Cs) share a common set of unusual physical properties that distinguish them from 'typical' transition metals.

1. Soft. Group 1 metals can be cut with a knife (Na and K cut like cheese; Cs is almost like butter). In contrast, iron and copper are HARD and need a saw or special tools. The softness arises from the weak metallic bonding — only one outer electron per atom contributes to the 'sea of delocalised electrons', so the metallic bonds are much weaker than in transition metals (which contribute 2-3 d/s electrons each).

2. Low density. Lithium, sodium and potassium all FLOAT on water (densities 0.53, 0.97 and 0.86 g/cm³ respectively — all less than water's 1.00 g/cm³). Even caesium (1.93 g/cm³) has a much lower density than iron (7.87 g/cm³) or copper (8.96 g/cm³). Reason: Group 1 atoms are LARGE (only s-shells; no d-electrons to pull atoms tighter) so atoms are spaced further apart.

3. Low melting and boiling points. Mp values: Li 181 °C, Na 98 °C, K 64 °C, Rb 39 °C, Cs 28 °C. Compare with Fe (1538 °C) or Cu (1085 °C). Reason: weak metallic bonding (only one outer e⁻ per atom in the sea) requires less energy to break. Note also that mp DECREASES down the group (because metallic bonds weaken as atoms get larger).

4. Shiny but rapidly tarnish. A freshly cut surface looks bright silvery — but within seconds it dulls because the metal reacts with O₂ and moisture in the air to form a dull oxide/hydroxide coating. In contrast, iron tarnishes much more slowly (it rusts over days/weeks) and copper produces a green patina over years. This is because Group 1 metals are EXTREMELY reactive.

Storage consequence. Because they tarnish so rapidly in air AND react violently with water, alkali metals are stored UNDER OIL (paraffin, mineral oil). The oil keeps both air and water away from the metal surface.

Comparison summary table.

Property	Group 1 (e.g. Na)	Transition metal (e.g. Fe)
Hardness	Soft (cut with knife)	Hard
Density	Low (~0.97 g/cm³)	High (~7.87 g/cm³)
Melting point	Low (98 °C)	High (1538 °C)
Reactivity	Very reactive	Less reactive
Tarnishing	Rapid (seconds)	Slow (rust over days)
Storage	Under oil	Open air

Why this scores

Edexcel 6-mark mark scheme: 1 each for FOUR valid properties (soft, low density, low mp/bp, tarnishes quickly, good conductor, shiny when fresh); 2 for valid comparisons / reasoning to transition metals. Common error: confusing 'low density' with 'low mass' — they are NOT the same. Density = mass/volume.

Question 2
4CH1/2C-style — extended reactivity trend6 marks
Explain why the reactions of Group 1 metals with water become MORE vigorous down the group, using ideas about electron arrangement and the energy required to lose an electron. Use Li, Na and K to illustrate your answer. (6 marks)
Model answer
Group 1 metals react with water following a single pattern: M(s) + H₂O(l) → MOH(aq) + ½H₂(g) (an exothermic redox reaction in which the metal is oxidised, M → M⁺ + e⁻, and water/H⁺ is reduced to H₂). The reaction's VIGOR — measured by how violently it proceeds and how exothermic it is — depends on how easily the metal atom can lose its outer-shell electron.

Electron arrangement. Each Group 1 atom has ONE outer-shell electron, sitting in the highest occupied s-orbital:

Lithium: 2,1 (outer electron in shell 2)

Sodium: 2,8,1 (outer in shell 3)

Potassium: 2,8,8,1 (outer in shell 4)

Rubidium: 2,8,18,8,1 (outer in shell 5)

Caesium: 2,8,18,18,8,1 (outer in shell 6)

Why the outer electron is held more loosely down the group.

Increasing atomic radius. Each successive Group 1 atom has an EXTRA filled inner shell, so the outer electron sits FURTHER from the nucleus. The electrostatic attraction force varies as 1/r² — doubling the distance quarters the attraction.

Increasing shielding. Inner filled shells SHIELD (partially cancel) the positive nuclear charge experienced by the outer electron. More inner shells → more shielding → weaker effective attraction.

Increasing nuclear charge (but outweighed). Although the nuclear charge does increase down the group (Li +3, Na +11, K +19, Rb +37, Cs +55), this increase is more than offset by the larger radius and greater shielding. So overall the OUTER electron is held LESS tightly.

The energy required to remove that outer electron (the 1st ionisation energy) therefore DECREASES down the group: Li 520 kJ/mol → Na 496 → K 419 → Rb 403 → Cs 376.

Vigor of reactions with water.

Lithium: floats, fizzes steadily, gradually disappears over minutes — gentle reaction.

Sodium: floats, fizzes vigorously, melts into a ball (low mp + exothermic), moves rapidly on the surface — vigorous reaction. Hydrogen sometimes pops at the end.

Potassium: floats, fizzes very violently, IGNITES — hydrogen burns with a LILAC flame, often ending with a small explosion. Reaction over in seconds.

(Rubidium, caesium: dangerously explosive — never demoed without protective enclosures.)

Linking the two ideas. Since the outer electron is lost more easily moving from Li → Na → K, the redox half-reaction M → M⁺ + e⁻ proceeds faster and is more exothermic. More energy is released, which heats the products, melts the metal, ignites the hydrogen, and produces a more vigorous physical reaction. Hence reactivity INCREASES down the group.
Why this scores
Edexcel 6-mark mark scheme: 1 for outer electron is lost in reaction; 1 for atomic radius increases (more shells); 1 for shielding increases; 1 for attraction between outer e⁻ and nucleus decreases / easier to lose; 2 for valid observations comparing Li, Na, K. ECF allowed if reasoning is sound but observation list incomplete.
Question 3
4CH1/2C-style — comparison Group 1 vs Group 75 marks
Compare the trends in reactivity of Group 1 metals and Group 7 non-metals (halogens) down each group. Explain the trends in terms of atomic structure. (5 marks)
Model answer
Group 1 (metals): reactivity INCREASES down the group (Li < Na < K < Rb < Cs).

Group 1 atoms react by LOSING their single outer-shell electron to form a +1 cation (M → M⁺ + e⁻). Reactivity = ease of losing that electron. Going down the group:

Atomic radius increases (more electron shells).

Inner shells SHIELD the outer electron more.

Attraction between the nucleus and outer electron WEAKENS.

Outer electron is lost MORE easily → reactivity INCREASES.

Group 7 (non-metals, halogens): reactivity DECREASES down the group (F > Cl > Br > I).

Group 7 atoms react by GAINING one electron to form a −1 anion (X + e⁻ → X⁻), completing their outer shell. Reactivity = ease of attracting and capturing an extra electron. Going down the group:

Atomic radius increases (more electron shells).

Inner shells SHIELD the incoming electron from the nucleus more.

Attraction between the nucleus and an incoming outer electron WEAKENS.

Electron is gained LESS easily → reactivity DECREASES.

Linking the trends. Both groups show the SAME atomic-structure effect (more shells + more shielding → weaker attraction to the outer/incoming electron), but because they react in OPPOSITE directions (Group 1 LOSES, Group 7 GAINS), the reactivity trends are OPPOSITE:

Property Group 1 Group 7
Reactive process Lose 1 e⁻ Gain 1 e⁻
Most reactive Bottom (Cs) Top (F)
Reactivity trend INCREASES down DECREASES down
Effect of more shells Easier to lose e⁻ Harder to attract e⁻

Sanity check. Caesium is the most reactive Group 1 metal (almost explodes in air). Fluorine is the most reactive Group 7 element — it reacts with almost everything. These are at the EXTREMES of the periodic table for losing or gaining one electron respectively.
Why this scores
Edexcel 5-mark mark scheme: 1 for stating Group 1 reactivity increases down + Group 7 decreases down; 1 for Group 1 'loses outer electron'; 1 for Group 7 'gains electron to outer shell'; 1 for atomic radius / shielding link in Group 1; 1 for atomic radius / shielding link in Group 7. Common error: applying the SAME trend to both groups.
Question 4
4CH1/1CR-style — storage of alkali metals5 marks
Explain why Group 1 metals are stored under oil. Describe what would happen if a piece of sodium were left exposed to the air for a few hours, and write equations for any reactions you mention. (5 marks)
Model answer
Why store under oil? Group 1 metals are EXTREMELY reactive — they react with both oxygen (in the air) AND moisture (water vapour). A coating of mineral oil (paraffin oil) physically prevents air and water from reaching the metal surface, keeping it bright and unreactive in storage.

What happens if sodium is left exposed.

First seconds — tarnishing. A fresh, shiny cut surface of sodium dulls within a few seconds as it reacts with oxygen in the air to form a thin coating of WHITE sodium oxide:

$4\text{Na(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Na}_2\text{O(s)}$

Minutes to hours — hydroxide formation. The oxide coating then reacts with water vapour in the air to form sodium hydroxide:

$\text{Na}_2\text{O(s)} + \text{H}_2\text{O(l)} \rightarrow 2\text{NaOH(s)}$

Continued exposure — solution droplets. NaOH is hygroscopic (absorbs water vapour) and DELIQUESCENT — it absorbs enough water to dissolve and form a wet film of NaOH solution on the surface. The solid sodium beneath continues to react.

Carbonate formation. Over hours, sodium hydroxide also reacts with carbon dioxide in the air:

$2\text{NaOH} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O}$

The final visible product is a white, crusty layer of sodium carbonate over the (now-shrunken) metal.

Safety hazards.

Burns: if a large piece is left exposed, the heat of reaction can be enough to ignite the metal, producing a fierce orange-yellow flame (Na fire).

Caustic surface: the hydroxide layer is strongly alkaline (pH > 13) — burns skin and eyes on contact.

Wet sodium reacts EXPLOSIVELY: if water condenses on a large piece, the violent reaction with water can throw molten sodium around — a serious lab hazard.

For these reasons, alkali metals must always be stored under oil, handled with tweezers, and disposed of in small pieces dropped into a large volume of cold ethanol (less violent than water).
Why this scores
Edexcel 5-mark mark scheme: 1 for stating Na reacts with air/oxygen; 1 for stating Na reacts with moisture; 1 for oil as a barrier to both; 1 for at least one correct equation (4Na + O₂ → 2Na₂O or 2Na + 2H₂O → 2NaOH + H₂); 1 for further detail (tarnishes / carbonate / safety hazard).

Property	Group 1	Group 7
Reactive process	Lose 1 e⁻	Gain 1 e⁻
Most reactive	Bottom (Cs)	Top (F)
Reactivity trend	INCREASES down	DECREASES down
Effect of more shells	Easier to lose e⁻	Harder to attract e⁻

Key Definitions and Keywords — Group 1

Definitions to memorise and the exact keywords mark schemes credit for group 1 answers — sharpened from recent examiner reports for the 2026 Pearson Edexcel IGCSE 4CH1 sitting.

Group 1 (alkali metals)
Examiner keyword
The first column of the periodic table containing Li, Na, K, Rb, Cs, Fr. Each has one outer-shell electron and forms a +1 ion. They are soft, low-density, low-melting-point metals that react vigorously with water to form alkaline hydroxides + hydrogen.
Alkali
Examiner keyword
A soluble base — a substance whose aqueous solution has pH > 7. Group 1 hydroxides (LiOH, NaOH, KOH, etc.) are strong alkalis, turning red litmus blue and universal indicator purple.
Reactivity (of a metal)
Examiner keyword
How readily a metal loses its outer electron(s) to form positive ions. For Group 1, reactivity is judged by the speed/violence of the reaction with water (and with oxygen and halogens). Reactivity INCREASES down Group 1.
Shielding (screening)
Examiner keyword
The reduction of the effective nuclear attraction felt by an outer-shell electron because of the partial cancellation by inner-shell electrons. Going down Group 1, more inner shells → more shielding → weaker attraction on the outer electron.
Flame test
Examiner keyword
Identification of certain metal ions by the characteristic colour they impart to a Bunsen flame. Procedure: clean nichrome wire in conc HCl, dip in sample, hold in blue flame. Li: crimson red; Na: orange/yellow; K: lilac.
Tarnish
The dulling of a freshly cut metal surface due to reaction with oxygen and moisture in the air, forming a thin oxide or hydroxide layer. Group 1 metals tarnish within seconds — hence stored under oil.
Deliquescent
Describes a solid that absorbs so much water vapour from the air that it dissolves in it, forming a solution. NaOH and KOH are deliquescent — visible as a wet film on alkali metal surfaces left in air.
Metal hydroxide (Group 1)
Examiner keyword
A compound MOH formed when a Group 1 metal reacts with water (or its oxide with water). Examples: LiOH, NaOH, KOH. All are soluble strong alkalis, with pH 13-14 in solution.
Outer-shell (valence) electron
Examiner keyword
The electron(s) in the highest occupied principal quantum shell. Group 1 atoms each have exactly ONE outer-shell electron, which is the electron lost during their characteristic chemistry.
Atomic radius
Examiner keyword
A measure of the size of an atom — the distance from the nucleus to the outermost occupied shell. Atomic radius INCREASES down a group because each successive element has an additional electron shell.

Common Mistakes and Misconceptions — Group 1

The traps other students keep falling into on group 1 questions — taken from recent Pearson Edexcel IGCSE 4CH1 examiner reports and mark schemes — and how to avoid them.

✕Writing the wrong product for Group 1 + water (e.g. metal oxide instead of hydroxide)
4CH1 Examiner Reports 2022-2024
Why it happens
Confusing the reaction of the metal with water (gives MOH) with the reaction of the metal with oxygen (gives M₂O).
How to avoid it
REMEMBER: Group 1 + WATER → metal HYDROXIDE + hydrogen (2M + 2H₂O → 2MOH + H₂). Group 1 + OXYGEN → metal OXIDE (4M + O₂ → 2M₂O). Different reactants → different products.
✕Stating that reactivity DECREASES down Group 1 (confusing with Group 7)
Why it happens
Mixing up Group 1 and Group 7 trends — both have a 'down-the-group' trend but in opposite directions.
How to avoid it
Group 1 LOSES an electron — easier with more shells → reactivity INCREASES down. Group 7 GAINS an electron — harder with more shells → reactivity DECREASES down. Remember: 'lose easier' vs 'gain harder'.
✕Saying 'nuclear charge decreases down the group' to explain reactivity
4CH1 Examiner Reports 2023-2024
Why it happens
Thinking that less attraction means less charge.
How to avoid it
Nuclear charge INCREASES down the group (more protons). But the INCREASE in atomic radius and shielding OUTWEIGHS the rise in nuclear charge → net attraction on the outer electron DECREASES. Use 'distance + shielding outweigh nuclear charge'.
✕Writing 'Na + H₂O → NaOH + H' (forgetting the diatomic hydrogen molecule)
Why it happens
Forgetting that hydrogen gas is H₂, not H.
How to avoid it
Hydrogen GAS is ALWAYS diatomic H₂. Balanced equation: 2Na + 2H₂O → 2NaOH + H₂ (two Na to make one H₂). Same for Li, K, Rb, Cs — always use H₂.
✕Writing 'yellow' as the flame colour of lithium
4CH1 Examiner Reports 2022-2024
Why it happens
Confusing Li with Na — sodium gives the bright yellow that's most familiar.
How to avoid it
Li = CRIMSON RED. Na = ORANGE-YELLOW (the brightest, most familiar). K = LILAC. Memorise: 'Lily Red, Nancy Yellow, Kate Lilac'.
✕Saying 'more energy levels' instead of 'more inner shells' / 'more shielding'
4CH1 Examiner Reports 2022-2024
Why it happens
Loose terminology — energy levels and shells are related but the mark scheme expects the link to shielding.
How to avoid it
Mark scheme rewards: 'more inner electron shells → more SHIELDING → weaker attraction'. Always link more shells to SHIELDING of the outer electron.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Group 1 — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Group 1 — Alkali Metals — Pearson Edexcel International GCSE Chemistry 4CH1 Study Notes (2026 onwards, Spec Issue 4)

Element	Mp	Bp
Li	181	1342
Na	98	883
K	64	759
Rb	39	688
Cs	28	671

Element

181

1342

883

759

688

671

Element

1st IE (kJ/mol)

520

496

419

403

376

Ion

Flame colour

Li⁺

Crimson red

Na⁺

Orange-yellow / 'golden'

K⁺

Lilac (pale purple)

Rb⁺

Red-violet

Cs⁺

Blue

Predicted property 1 — Extreme reactivity with water.

Continuing the trend Li < Na < K < Rb < Cs, francium would react EVEN MORE VIOLENTLY than caesium — almost certainly explosively. Equation predicted:

$2\text{Fr(s)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{FrOH(aq)} + \text{H}_2\text{(g)}$

Predicted property 2 — Very low melting point.

Predicted property 3 — Soft, low density.

Like Cs but even softer. Density predicted ~2.0-2.5 g/cm³ — still low for a metal, continuing the trend Cs 1.93.

Predicted property 4 — Forms strongly alkaline FrOH.

By extension, Fr would form a STRONG alkali FrOH in water — more alkaline than KOH or CsOH. Reacts with acids to form a salt + water.

Predicted property 5 — Brilliant flame test colour.

Extrapolating from the colour trend, francium's flame test would be expected to be a redder/more orange colour relative to Cs's blue — though it has never been measured in bulk quantity.

Strategy for exam questions about Fr. When asked to predict properties of Fr, always:

State the relevant Group 1 trend (reactivity, mp, density, etc.).
Apply the trend to Fr (more reactive, lower mp, etc.).
Justify briefly with atomic structure (more shells, more shielding, outer e⁻ further out).

Examiners reward atomic-structure REASONING, not just 'because it's at the bottom'.

Property

Group 1 (e.g. Na)

Transition metal (e.g. Fe)

Hardness

Soft (cut with knife)

Hard

Density

Low (~0.97 g/cm³)

High (~7.87 g/cm³)

Melting point

Low (98 °C)

High (1538 °C)

Reactivity

Very reactive

Less reactive

Tarnishing

Rapid (seconds)

Slow (rust over days)

Storage

Under oil

Open air

Property	Group 1	Group 7
Reactive process	Lose 1 e⁻	Gain 1 e⁻
Most reactive	Bottom (Cs)	Top (F)
Reactivity trend	INCREASES down	DECREASES down
Effect of more shells	Easier to lose e⁻	Harder to attract e⁻

Property

Group 1

Group 7

Reactive process

Lose 1 e⁻

Gain 1 e⁻

Most reactive

Bottom (Cs)

Top (F)

Reactivity trend

INCREASES down

DECREASES down

Effect of more shells

Easier to lose e⁻

Harder to attract e⁻

Group 1

Short Study Notes in the form of Slides

Short Study Notes — Group 1

Detailed Notes

What you’ll learn

How it’s examined

1Sodium added to water — observations + equation (5 marks, Paper 1)

2Explain the trend in reactivity down Group 1 (5 marks, Paper 1)

3Potassium with water — equation and observations (3 marks)

4Predict the properties of francium (5 marks, Paper 1)

5Identify Group 1 ions using flame tests (5 marks, Paper 1)

Group 1 (alkali metals)

Alkali

Reactivity (of a metal)

Shielding (screening)

Flame test

Tarnish

Deliquescent

Metal hydroxide (Group 1)

Outer-shell (valence) electron

Atomic radius

✕Writing the wrong product for Group 1 + water (e.g. metal oxide instead of hydroxide)

✕Stating that reactivity DECREASES down Group 1 (confusing with Group 7)

✕Saying 'nuclear charge decreases down the group' to explain reactivity

✕Writing 'Na + H₂O → NaOH + H' (forgetting the diatomic hydrogen molecule)

✕Writing 'yellow' as the flame colour of lithium

✕Saying 'more energy levels' instead of 'more inner shells' / 'more shielding'

Practice questions

Past paper style quiz

Assess your understanding

Group 1 — frequently asked questions

Group 1

Short Study Notes in the form of Slides

Short Study Notes — Group 1

Detailed Notes

What you’ll learn

How it’s examined

1Sodium added to water — observations + equation (5 marks, Paper 1)

2Explain the trend in reactivity down Group 1 (5 marks, Paper 1)

3Potassium with water — equation and observations (3 marks)

4Predict the properties of francium (5 marks, Paper 1)

5Identify Group 1 ions using flame tests (5 marks, Paper 1)

Group 1 (alkali metals)

Alkali

Reactivity (of a metal)

Shielding (screening)

Flame test

Tarnish

Deliquescent

Metal hydroxide (Group 1)

Outer-shell (valence) electron

Atomic radius

✕Writing the wrong product for Group 1 + water (e.g. metal oxide instead of hydroxide)

✕Stating that reactivity DECREASES down Group 1 (confusing with Group 7)

✕Saying 'nuclear charge decreases down the group' to explain reactivity

✕Writing 'Na + H₂O → NaOH + H' (forgetting the diatomic hydrogen molecule)

✕Writing 'yellow' as the flame colour of lithium

✕Saying 'more energy levels' instead of 'more inner shells' / 'more shielding'

Practice questions

Past paper style quiz

Assess your understanding

Group 1 — frequently asked questions