Predicting structures and properties

In a nutshell

The structure of a compound can be predicted by looking at its properties.

There are several different properties that can be looked at to determine the structure of a compound:

Melting and boiling point - determines strength of attraction
Electrical conductivity - determines whether there are any free or charged particles
Solubility in water - determines the ability to form hydrogen bonds or if ions are charged

Below is table of the different properties shown for each type of bonding.

bond	MELTING/ BOILING POINT	STATE AT R.T.P	electrical CONDUCTIVITY	sOluble in water	EXAMPle
Ionic	High	Solid	Solid - no Liquid - yes, ions are broken down and are free to move	Yes	$BaCl_2$
Simple covalent	Low - no covalent bonds are broken	Normally liquid / gas	No	Dependant on hydrogen bond formation	$F_2$
Giant covalent	High	Solid	Solid - no, except graphite / graphene Liquid - N/A sublimes to a gas	No	$SiO_2$
Metallic	High	Solid	Yes, the structure contains delocalised electrons	No	$Na$

Note: R.T.P stands for room temperature and pressure.