Physical Science: Chapter 4 Vocab

Atom

Smallest particle of an element.

Electron

A subatomic particle that has a negative charge.

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom.

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom.

Atomic Number

The number of protons in the nucleus of an atom.

mass number

The sum of the number of neutrons and protons in an atomic nucleus.

Isotope

Atoms of the same element that have different numbers of neutrons.

Atomic Mass Unit

A unit of mass that describes the mass of an atom or molecule.

mole

The SI base unit used to measure the amount of a substance.

Orbital

A region in an atom where there is a high probability of finding electrons.

Emission

The production and discharge of something, especially gas or radiation.

Valence Electrons

Electrons on the outermost energy level of an atom.

Photons

Particles of light

Electric Force

The force of attraction or repulsion on a charged particle that is due to an electric field.

Law of Definite Proportion

States that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.

Radioisotope

An isotope that has an unstable nucleus and undergoes radioactive decay.

Assume

To take for granted or without proof.