Question 1

What is the trend in atomic radius across Period 3 of the Periodic Table?

Accepted Answer

In Period 3, the atomic radius decreases from left to right across the period. This is because as you move across the period, the number of protons in the nucleus increases, leading to a greater nuclear charge. This increased attraction pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.

Question 2

How does the electronegativity change across Period 3 elements?

Accepted Answer

Electronegativity increases across Period 3 from left to right. This is due to the increasing nuclear charge, which attracts the bonding pair of electrons more strongly. Elements like sodium have lower electronegativity, while chlorine has a higher electronegativity, reflecting its strong ability to attract electrons.

Question 3

Why do the melting and boiling points vary across Period 3?

Accepted Answer

The melting and boiling points of Period 3 elements vary due to differences in their structures and bonding. Metals like sodium, magnesium, and aluminum have metallic bonding, which is strong and leads to higher melting and boiling points. Silicon, a metalloid, has a giant covalent structure, resulting in very high melting and boiling points. Non-metals like phosphorus, sulfur, and chlorine have molecular structures with weaker van der Waals forces, leading to lower melting and boiling points.

Question 4

What is the trend in ionization energy across Period 3?

Accepted Answer

Ionization energy generally increases across Period 3. This is because the increasing nuclear charge across the period results in a stronger attraction between the nucleus and the outer electrons, making it more difficult to remove an electron. However, there are slight deviations due to electron configurations, such as the drop between magnesium and aluminum, and phosphorus and sulfur.

Question 5

How do the chemical properties of Period 3 elements change across the period?

Accepted Answer

The chemical properties of Period 3 elements change from metallic to non-metallic as you move from left to right. Metals like sodium and magnesium react by losing electrons, while non-metals like chlorine gain electrons during reactions. This change is due to the increasing electronegativity and ionization energy across the period, which influences how these elements interact with other substances.

Periodicity of chemical properties of the elements in Period 3

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Periodicity of chemical properties of the elements in Period 3 — frequently asked questions