Question

atoms become ions when
electrons are gained or lost.
all atoms are ions.
the number of neutrons equals the number of electrons.
a proton is donated to an energy shell.
bonds are formed between atoms.

Explanation:

An ion is an atom or molecule with a net electrical charge. This occurs when electrons are gained (anion) or lost (cation). Atoms are neutral in their normal state, not all are ions. Neutron - electron equality doesn't define ions. Protons are in the nucleus and not donated to energy shells to form ions. Bond - formation is a different concept from ion - formation.

Answer:

electrons are gained or lost.