What we have learned so far


Anything that has mass and takes up space. There are three states of matter: Solid, liquid, gas.


A substance made up of atoms and different elements.

Pure Substances

Matter that has a fixed composition and define properties.


A mixture in which the composition is constant throughout. Also called a solution.

Greek Philosophers

Democritus: First person to propose the idea that matter was not infinitely divisible Aristotle: disagreed with Democritus because he did not believe empty space could exist. John Dalton: explained conservation of mass in reaction as the result of the combination, separation, or rearrangement of atoms.


Positive charged particles in the nucleus.

Atomic Numbers

The number of protons in the nucleus of an atom that identifies the element.