1.
The smallest unit of matter that makes up everything
2.
A theory that says all matter is made of tiny, indivisible atoms.
3.
A tiny, negatively charged particle that orbits an atom’s nucleus.
4.
A stream of electrons observed in vacuum tubes.
5.
A particle in the nucleus of an atom with Positive charge.
6.
A particle in the nucleus of an atom with no charge.
7.
The central part of an atom containing protons and neutrons.
8.
The number of protons in an atom’s nucleus.
9.
The total number of protons and neutrons in an atom.
10.
Atoms of the same element with different numbers of neutrons.
11.
A unit used to measure the mass of atoms and particles.
12.
The average mass of an element’s atoms, considering all isotopes.
