For each of the following pairs of elements (1C and N2) (1Ar and Br2)
pick the atom with
a. more favorable (exothermic) electron affinity.
b. higher ionization energy.
c. larger size.
How do you even go about do this?

1. a. C; b. N; c. C; 2. a. Br; b. Ar; c. Br

Explanation:

Use your Periodic Table and follow the trends in atomic properties (Fig. 1).

Electron affinity increases from left to right and from bottom to top.

The elements with the most exothermic EA are at the upper right corner

Exceptions are the noble gases (group 18) and the pnictogens (group 18).

The elements of Group 18 have a complete octet and have no tendency to accept electrons.  

The elements of Group 15 have half-filled p subshells. They are more stable than the elements immediately preceding them, so they are less exothermic when adding an electron.  

Ionization energy increases from left to right and from bottom to top.  

The atoms with the highest IE are at the upper right corner.

Atomic size increases from right to left and from bottom to top.  

The largest atoms are on the lower-left corner.

1. C vs N

(a)   EA: C. N is a Group 15 element

(b)    IE: N. N is further to the right.

(c) Size: C. C is further to the left.

2. Ar vs Br

(a)   EA: Br. Ar is a noble gas.

(b)    IE: Ar. Ar is further to the right.

(c) Size: Br. Br is nearer to the bottom.

answer: mole of the gas

answer: mole of the gasexplanation: