Trends In The Periodic Table

Question 1

What is the atomic radius (covalent radius) of an atom?

Answer 1

Half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond

Question 2

Describe the trend in the values of the atomic radius down the groups.

Give two reasons for this.

Answer 2

The values of the atomic radius increase down the groups

New energy levels
Screening effect of inner electrons

Question 3

Describe the trend in the values of the atomic radii across a period.

Give two reasons for this

Answer 3

The values of the atomic radius decrease across a period

Increase in effective nuclear charge - attractive force on the outer electrons - draws electrons in

No increase in screening effect

Question 4

What is first ionization energy of an atom?

Answer 4

The minimum energy required to completely remove the most loosely bound electron from a neutral gaseous atom in it’s ground state.

Question 5

Describe the trend in values of the first ionisation energy down a group.

Give two reasons for this

Answer 5

The values of the first ionisation energy decrease down a group

Increasing atomic radius - e further away from nucleus

Screening effect of inner electrons

Question 6

Describe the trend of the values of the first ionisation across a period.

Give two reasons for this

Answer 6

The values of the first ionisation energy increase across a period

Increasing effective nuclear charge - positive nuclear charge drawing electrons in - more protons

Decreasing atomic radius

Question 7

What is the second ionisation energy?

Answer 7

The energy required to remove an electron from an ion with one positive charge in the gaseous state

Question 8

Describe the trend in the values of electronegativity down the group

Give two reasons.

Answer 8

The values of electronegativity decrease down the group

Increasing atomic radius - further away from nucleus

Screening effect of inner electrons

Question 9

Describe the trend in the values of electronegativity across the periods.

Give two reasons

Answer 9

The values of electronegativity increase across the periods

Increasing effective nuclear charge - more protons - more positive pull inwards on electrons

Decreasing atomic radius - closer to nucleus - greater attraction between nucleus and electrons