How many phosphorus atoms would combine together to form a stable molecule

Four  

Explanation:

P has five valence electrons. It can form bonds to three other atoms (like H) to form a triangular pyramidal molecule with a lone pair on the P atom.

If P atoms are to form bonds with each other, we can get a stable arrangement by putting each atom at the corner of a tetrahedron.

In a P₄ molecule, each atom still has three bonds and a lone pair.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.