Topic 7: Periodic Trends, Video E: Electron Affinity

Question 1

What is electron affinity?

Answer 1

The heat released when a gaseous atom gains an electron to create a negative ion.

Question 2

The more negative the delta H value the more heat is released and the larger the what?

Answer 2

The larger the electron affinity meaning the ion is more stable than the atom.

Question 3

Which element has the greates electron affinity?

Answer 3

Chlorine.

Question 4

The electron affinity is a measure of what?

Answer 4

The energy released.

Question 5

Which group on the periodic table has the largest/most favorable electron affinity?

Answer 5

The halogen group. Group 17.

Question 6

Electron affinity increases or decreases down a group?

Answer 6

Decreases.

Question 7

How can halogens having the highest electron affinity be explained?

Answer 7

Each halogen already has 7 valence electrons in its p orbitals. Gaining one is more favorable. As you move down the group the atoms get bigger. The electron you add is further from the nucleus. The binding energy (based on electrostatic) is weaker.

Question 8

What are the exceptions to the electron affinity decreasing as you go down the groups?

Answer 8

The atoms in the p block of period 2 have electron affinity values that are lower than the atoms in period 3. This is probably because the period 2 atoms are extremely small and the electron electron repulsions are greater than in period 3.

Question 9

When atomic radius increases, I₁ increases or decreases and electron affinity becomes more or less positive?

Answer 9

When atomic radius increases, I₁ decreases and electron affinity becomes less positive.