Most of the mass of an atom is located in the electrons of the atom.

Electrons occupy most of the volume of an atom.

The positive charges in an atom are spread uniformly throughout the entire atom.

Electrons occupy most of the volume of an atom.

The positive charges in an atom are spread uniformly throughout the entire atom.

Some positively charged alpha particles were deflected rather than passing straight through thin metal foil. To explain this, Rutherford postulated that the nucleus of the atom must be positive.

Ions are

A cation is a

Cathode rays are beams of

An anion is a

The atom is the fundamental building block of everything we hear, feel, see, and experience.

John Dalton was the first person recorded as thinking that matter was ultimately composed of atoms.

John Dalton formalized an atomic theory that gained acceptance in the early 19th century.

The plum pudding model proposed that negatively charged electrons were held in a sphere of positive charge.

All of the positive charge of an atom is concentrated in the nucleus.

J.J. Thomson discovered the existence of protons.

Ernest Rutherford proved the existence of electrons.

The gold foil experiment proved that large regions of the atoms consisted of empty space.

The nucleus of an atom is a very small, dense region that contains over 99.9% of the atomic mass.

A positive charge attracts negative charges and repels other positive charges.

The charges on electrons and neutrons cancel each other to give neutral atoms.

Protons and neutrons have similar masses and similar electrical charges.

An atom containing 8 protons, 9 neutrons, and 8 electrons would be considered charge-neutral.

The number of protons in an atom's nucleus defines the element.

If two atoms each contain different numbers of protons, the atoms must be from different elements.