Group 15 elements have 5 valence electrons. They accept three electrons and form anions of -3 charge.
For example: N3- (nitride ion) or P3- (phosphide ion)
They can form ionic compounds with halogens.
Why does group 4A elements tend to form covalent bonds rather than ionic bonds? 
Elements on opposite sides of the periodic table, for example Groups 1 and 17, form ionic compounds. Examples include LiCl, NaCl, KI, and RbBr. The elements in Group 1 are the alkali metals, and the elements in Group 17 are the halogens, which are nonmetals.
The Center
i dunno my dumb teacher wants me to find out she should ask a dam scientist!
These bonds tend to be ionic. However, all bonds are somewhere between purely ionic and purely covalent.
They tend to have low electronegativity which means they donate their electrons in ionic compounds. They are metals and when they have one or more less electrons than protons they will have a positive charge.
They can form ionic compounds with halogens.
Why does group 4A elements tend to form covalent bonds rather than ionic bonds? 
Elements on opposite sides of the periodic table, for example Groups 1 and 17, form ionic compounds. Examples include LiCl, NaCl, KI, and RbBr. The elements in Group 1 are the alkali metals, and the elements in Group 17 are the halogens, which are nonmetals.
The Center
i dunno my dumb teacher wants me to find out she should ask a dam scientist!
If you think to halogens they form ionic bonds with metals.
The boiling points of ionic solids tend to be very high.
True, non-metals would gain electrons to form anions with a negative charge.
Yes it is. Ionic bonds tend to form between metals and nonmetals.
Metals and nonmetals tend to form ionic compounds by forming ionic bonds when they combine.