The small core of the atom; contains neutrons and protons

A part of the nucleus; has a positive charge and mass of 1 amu.

Part of the nucleus; has no charge, and a mass of 1 amu.

Moves around the nucleus; has a negative charge and mass of 1/2000 amu.

Is made up of a single type of atom. It is identified by the number of protons in the nucleus. A pure substance that cannot be broken down into other substances.

A group of two or more atoms held together by chemical bonds.

A substance made of two or more elements chemically combined in a set ratio. Example:  $H_2O,\ CH_4$  

Two or more substances that are together, but NOT chemically combined.

Substances that are evenly mixed so that you cannot see the different parts.

A mixture that you can see the different parts of.

The sum of both the protons and neutrons in the nucleus.

The unit used to measure the mass of particles in the atom.

The Atomic Number is the number of which particles in the atom?

The combination of charged particles in the atom makes up the _______.

When different atoms have the same number of protons but different number of neutrons, they are called ________.

He was an ancient Greek philosopher who believed the atom was a solid thing that could not be divided.

He was an English chemist who proposed that elements are made of atoms of a single type and can be combined to form more complex structures.

He was an English physicist who discovered the electron using a cathode ray tube. His model of the atom proposed a positively charged atom that was peppered with negatively charged atoms, also called the "Plum Pudding Model".

He was the "father of nuclear physics". He discovered the nucleus of the atom with his famous gold foil experiment. His model is called the planetary model. A positively charged nucleus, which contains most of the atom's mass, is at the center and negatively charged electrons orbit around like planets.

A Danish physicist, his model proposed that electrons orbited the nucleus at specific distances based on their energy.

A model of the atom where electrons exist in clouds of probability around the nucleus