is defined as anything that has mass and takes up space (it has volume).

the basic unit of a chemical element

group of atoms bonded together, representing the smallest fundamental unit of a chemical compound

a stable subatomic particle in the nucleus with positive electric charge equal in magnitude to that of an electron, but of opposite sign.

subatomic particle of about the same mass as a proton and is neutral.

a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.

a grouping of electrons surrounding the nucleus of an atom.

substance whose atoms all have the same number of protons.

the amount of space an object takes up

degree of consistency measured by the quantity of mass per unit volume.

the number of protons and neutrons in the atom, also referred to as a mass number

the number of protons in the nucleus of an atom