Ions are atoms with a charge other than zero. In a neutral atom, the number of protons (positively charged particles) in the nucleus equals the number of electrons orbiting the nucleus.
Atoms can gain or lose electrons (not protons) resulting in a net charge other than zero. Atoms which lose electrons (usually metals) become positively charges, and atoms which gain electrons (usually nonmetals) become negatively charged.
At least, that's what Bohr<span> decided, and that's why he proposed the </span>existence<span> of the</span>atomic<span> energy level. </span>According<span> to </span>Bohr<span>, the electrons in an </span>atom<span> were only allowed to </span>exist<span> at certain energy levels</span>
A compound<span> is a </span>molecule<span> that contains at least two different elements. </span>All compounds<span> are </span>molecules<span> but not </span>all molecules<span> are </span>compounds<span>. </span>Molecularhydrogen (H2<span>), </span>molecular<span> oxygen (O</span>2<span>) and </span>molecular<span> nitrogen (N</span>2) are notcompounds<span> because each is composed of a single element.</span>
