Worksheet titled "Periodic Trends Worksheet" featuring questions on atomic radius, ionization energy, and periodic trends, placed on a white surface with a yellow background.

1. a) K
b) Ca
c) Ga
d) O
e) Br
f) Ba
g) Si
h) Au

2. Atomic size increases from top to bottom in a group. Atomic size decreases from left to right in a period.

3. As you move left to right across a period, the number of protons and electrons increases. The added electrons go into the same principal energy level, so the increasing nuclear charge pulls the electron cloud closer to the nucleus, making the atom smaller.

4. a) O
b) F
c) F
d) Cu
e) Ne
f) V
g) Br
h) Se