The chemical formula (not symbol) of boron chloride is BCl3.
Boron is an element.
Boron is an element and contains only atoms of Boron.
boron tetra chloride
Potassium chloride, KCl, is a compound.
Sodium chloride is a compound with the formula NaCl. There is no compound that contains sodium chloride.
The formula for the ionic compound barium chloride is BaCl2.