Who this is for: Cambridge IGCSE Chemistry (0620) students who want the Periodic Table — groups, periods and how atomic number drives position — to become a reliable framework instead of a diagram they only half-memorise.
What query it owns: how to understand and revise the Periodic Table in Cambridge IGCSE Chemistry.
Why this is safe: this page owns the Periodic Table revision-guide angle, while Tutopiya’s The Periodic Table subtopic page owns the learning resource and the free Periodic Table quiz owns the practice.

The Periodic Table is the organising map of Cambridge IGCSE Chemistry (0620). Elements are arranged by atomic number, grouped into vertical columns (groups) with similar chemical properties and horizontal rows (periods) that show trends across shells. Examiners expect you to read position, deduce electronic structure and predict reactivity. This guide explains the layout, the ideas that repeat in every paper, and where to practise each skill.

Key takeaways

• Atomic number equals the number of protons and defines an element’s position in the table.
• Groups are vertical columns; elements in the same group have the same number of outer-shell electrons.
• Periods are horizontal rows; each new period starts a new electron shell.
• Metals lie to the left and centre; non-metals to the right; metalloids sit on the staircase boundary.
• Use group number (for Groups I–VII) to predict valency and typical ion charge.

What is the Periodic Table in Cambridge IGCSE Chemistry?

The Periodic Table is a chart of all known elements arranged in order of increasing atomic number. In Cambridge IGCSE Chemistry it is used to predict electronic configuration, compare reactivity and link elements to their compounds. Modern tables are based on Mendeleev’s work, refined when atomic number — not relative atomic mass — was shown to govern chemical behaviour.

Read the full explanation and worked examples on Tutopiya’s The Periodic Table subtopic page before you attempt questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Atomic number (Z)	Number of protons in the nucleus	”Element X has atomic number 17 — which group is it in?”
Group number	Vertical column; same outer electrons	Predict ion charge: Group I → +1, Group VII → −1
Period number	Horizontal row; number of occupied shells	”How many electron shells does sodium have?”
Metal vs non-metal	Left/centre vs right of table	Compare conductivity, oxides, chlorides
Noble gases (Group 0)	Full outer shell; unreactive	Explain why helium and neon do not form compounds easily

How to use the Periodic Table — step by step

1. Find the atomic number on the element key or data booklet.
2. Write the electronic configuration — shells fill in order 2, 8, 8… for the first 20 elements.
3. Count outer-shell electrons to identify the group (for Groups I–VII).
4. Count occupied shells to identify the period.
5. Compare position with neighbours to predict whether an element is metal or non-metal.
6. Check the mark scheme wording — “group” and “period” must not be swapped.

Once you have worked through a few, test yourself with the free Periodic Table quiz — it tells you fast whether the layout has actually stuck.

Groups vs periods: which detail does the question want?

Situation	What to read from the table	Typical signal words
Ion formation	Group number → electrons lost/gained	”forms a 2+ ion”, “Group II”
Reactivity trend	Position in group or period	”more reactive down the group”
Metal character	Left vs right position	”metallic character decreases across a period”
Electronic structure	Period = shells; group = outer electrons	”state the electronic configuration”

The Periodic Table in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical Periodic Table stem
State / Name	Give group, period or element	”State which group magnesium is in.”
Explain	Link position to properties	”Explain why chlorine is more reactive than bromine.”
Predict	Use table position	”Predict the formula of the oxide of element X in Group II.”
Compare	Two elements in same group or period	”Compare the reactivity of lithium and potassium.”
Deduce	Work backwards from data	”Deduce the number of outer-shell electrons.”

Worked exam-style stems (how to answer the wording)

1. “Sodium has atomic number 11. State its group and period.” Configuration 2,8,1 → Group I, Period 3. Mark-scheme reward: outer electron count linked to group.
2. “Element Q is in Group VII and Period 3. Name element Q.” Third period halogen → chlorine. Reward: correct element name from position.
3. “Explain why elements in the same group have similar chemical properties.” Same number of outer-shell electrons → similar bonding and reactivity. Reward: electronic structure, not just “same group”.

When you can recognise the wording instantly, work through the Periodic Table quiz and linked subtopics to lock the method in.

How the Periodic Table connects to the rest of the course

The table underpins Periodic Trends, Group Properties and Noble Gases. It also feeds into bonding, Redox and the Metals unit. The Cambridge IGCSE Chemistry resource hub keeps all units in one place.

Common mistakes students make

• Confusing group (column) with period (row).
• Using relative atomic mass instead of atomic number to justify position.
• Stating “same number of electrons” instead of outer-shell electrons for group similarity.
• Forgetting that Group 0 noble gases have a full outer shell, not zero outer electrons.
• Naming the wrong halogen when period number is misread.

When you need more support

If table-reading questions keep tripping you up, work through the Periodic Table quiz to pinpoint the exact gap, then get focused help from a Cambridge IGCSE Chemistry tutor to fix it quickly.

Frequently asked questions

Is the Periodic Table hard in Cambridge IGCSE Chemistry? The layout is straightforward. Marks are lost when students swap groups and periods or fail to link position to electronic structure.

How do I find an element’s group from its configuration? Count the electrons in the outer shell. For Groups I–VII, that number matches the group (with Group 0 as the exception — full outer shell).

Why are elements in the same group similar? They have the same number of electrons in the outer shell, so they form similar types of bonds and compounds.

How do I revise the Periodic Table effectively? Read the subtopic notes, practise deducing group and period from atomic number, then take the Periodic Table quiz. Revisit any electronic-structure errors before moving on.

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