is the atomic radius of germanium lager or smaller than bromine

Answer 1

Ge is larger, Br is smaller

Simple explanation: Radius increases moving down a family, and to the left.

More detailed explanation:

Coulomb's law

Force=(charge magnitude)/distance between charges

F=(Q1Q2)/d

F=force between charges

Q1Q2=magnitude of charge (+-1, +-2, +-3, etc. bigger numbers=stronger force)

d=distance between charges. smaller distance=stronger force

Consider Ge and Br

Ge:

1. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^2
2. 32 protons

Br:

1. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5
2. 35 protons

For Br, there are more p+’s in the nucleus (Q1Q2 increases), but e–‘s are in the same shell (4s, 4p, distance is constant). The force increases, so the nucleus pulls the valence e–‘s “in” more strongly to decrease the radius.