1. Atomic Trends: Electron Affinity
Definition:
Electron Affinity (E.A.)
An atom’s E when an electron is added.
(+) Endothermic
Energy is required as the additional electron is added.
Atom’s internal energy goes up.
“Unwelcome electron” since additional E is required
(-) Exothermic
Energy is release as the additional electron is added
Atom’s internal energy goes down.
“Welcome electron” energy is released

2. Atomic Trends Atomic Size: Size of atom Large E.A.
Small atoms
Large atoms
Atomic Size: Size of atom
Large E.A.
Small E.A.
Electron Affinity (E.A.) Energy released/absorbed with the addition of an extra e-
Large I.E.
Small I.E.
Ionization Energy (I.E.) Energy required to remove an e-

3. Atomic Trends: Electron AffinityB 5
10.811 C 6
12.011 N 7
14.007 O 8
16.000 F 9
18.998 Ne 10
20.18
(+) Endothermic
Un-Welcome e-
-50
-100
-150
-200
-250
-300
-350
+50 N Ne
e- UN-welcome B
Already full!
1s22s22p6 C O
e- Welcome
e- Welcome
1s22s22p2
(-) Exothermic
1s22s22p5
+ 1e- F
+ 1e-
Welcome e-
1s22s22p3
1s22s22p6
(...becomes ½ full!)
(...becomes full!)