Answer:
Step-by-step explanation:
A covalent compound is a compound formed by covalent bonds. A covalent bond is formed between two atoms where electrons are shared between the two atoms. This forms a molecule.
What determines whether two elements will form a covalent compound or not is the number of valence electrons present in each of the elements.
Fluorine will form a covalent compound with phosphorous because fluorine has 5 electrons in its outermost shell. It needs 3 more to become stable.
Phosphorous also has 5 valence electrons. It needs 3 more to become stable.
What happens is that 3 atoms of FLuorine combine with one atom of Phosphorus, sharing the valence electrons between themselves. This leads to the formation of the PF3 molecule.
Both the Phosphorous and the Fluorine are now stable.