Question

1. When a potassium atom reacts with a bromine atom, the
bromine atom will
a) lose 1 electron and form a positive ion
b) lose 2 electrons and form a positive ion
c) gain 1 electron and form a negative ion
d) gain 2 electrons and form a negative ion

I know its either C/D but im not sure which one.

Answer 1

Br is in group VII (or 17 depending upon the system your prof is using; either system, however, tells you there are 7 electrons in the outside shell. That means 1 electron is missing to make an outside shell of 8; therefore, it gains the 1 electron becoming a -1 charge in the process.