What will atoms with fewer than 8 electrons in their outermost shell do to become stable?

When atoms have fewer than 8 electrons, they tend to react and form more stable compounds.

Atoms will react to get in the most stable state possible. A complete octet is very stable because all orbitals will be full. Atoms with greater stability have less energy, so a reaction that increases the stability of the atoms will release energy in the form of heat or light. Reactions that decrease stability must absorb energy, getting hotter.

they will go get more from another shell

Explanation:

- lead + phosphoric acid = hydrogen + lead(ii) phosphate