Basic Concepts of Atoms

Atom: a particle so small that it cannot be seen without the help of a special microscope.

Nucleus: region at the center of an ato that contains most of the atoms mass.

Proton: positively charge in the nucleus of a atom.

Neutron: uncharged particle in the nucleus of the atom

Electron: negatively charged particle that occupies space outside the nucleus of a atom.

Electron cloud: region surrounding the nucleus of a atom in which one or more electrons are most likely to be found.

Atomic number: number of protons in the nucleus of a atom

Isotope: one of the two or more atoms of an element that have the same numbers of protons, but different numbers of neutrons.

lon: an atom that has a positive or negative charge because it has gained or lost electrons.