Is in the center of an atom and is composed of two different particles.

Is a positive particle that has a mass of 1 amu.

Is a negative particle with negligible mass.

Neutral subatomic particle with a mass of 1 amu.

This is the number of protons in the nucleus of a given element

The number of neutrons plus the number of protons

Two atoms of the same element with different numbers of neutron and different masses.

the fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus, can have

where electrons are when they go around the nucleus of an atom

actual or potential patterns of electron density that may be formed in an atom or molecule by one or more electrons

the lowest energy state of an atom or other particle