Covalent bond a chemical bond formed by two electrons that are shared between two atoms
ionic bond<span> a chemical bond formed by the electrostatic attraction between ions</span>
metallic bond<span> a bond characteristic of metals in which mobile valence electrons are shared among positive nuclei in the metallic crystal</span>
Hello there!
An Atom would be considered to be the smallest unit that would make up matter. If were to ever see a picture of an atom, they would consists of a proton, neutron, electron, and a nucleus. And all this would be called a Atom.
Your answer: Atom