Unit 2 part 3 - Ionic radius and electron affinity

Question 1

Why does ionization energy increase across a period?

Answer 1

B/c the increase in effective nuclear charge increases the attraction between the outer electrons and the nucleus making the electrons more difficult to remove

Question 2

Why does ionization energy decrease down a group?

Answer 2

B/c the electron removed is furthest from the nucleus

Question 3

What is electron affinity?

Answer 3

The energy change that occurs when one mole of an electron gets added to one mole of a gaseous atom

Question 4

What is the pattern of electron affinity across a period and down a group?

Answer 4

It increases across a period and decreases down a group

Question 5

The higher the magnitude the…

Answer 5

more likely to gain an electron

Question 6

Why is the process of electron affinity exothermic (releasing energy)?

Answer 6

B/c as the added electron is attracted to the positively charged nucleus the process gives out energy

Question 7

Why are the electron affinity not available for the noble gasses?

Answer 7

B/c they don’t take in electrons

Question 8

Why does group 17 elements attract the most electrons?

Answer 8

B/c they have incomplete outer energy levels and a higher effective nuclear charge

Question 9

Nuclear charge of group 17 elements?

Answer 9

Approximately +7

Question 10

The more negative the electron affinity the higher what?

Answer 10

The higher attraction to electrons

Question 11

Why do halogens have the highest electron affinity?

Answer 11

B/c they are one electron short of a sublevel

Question 12

Two exceptions to EA trend?

Answer 12

1. Group 2 has more positive EA than expected
2. Group 15 is also more positive than expected

Question 13

Why are the second EA values for O and S positive?

Answer 13

B/c the electron - to - electron repulsion must be overcome by adding energy