Atom  The smallest part of an element that has all the properties of that element.

Compound  Atoms from two or more different elements that are attached together in specific proportions.

Charge  A property of particles. Particles with opposite charges attract each other, while particles with the same charges repel.   

Electron  A negatively charged particle that orbits the center of the atom.

Element  A pure substance that can’t be broken down into simpler substances.

Heterogeneous Mixture  A mixture, such as cereal and milk, made of substances that are mixed but not dissolved together. 

Homogeneous Mixture  A mixture, such as lemonade, made of substances that are blended together and will not separate over time.  

Mass  The amount of material contained in an object, such as gold. An object's mass is always the same, even in outer space.

Matter  Any physical substance or material that takes up space and has mass. If you can put it in a jar, it’s matter. 

Mixture  A substance that consists of two substances mixed together.

Molecule Two or more atoms that are attached together.

Nucleus The center of the atom, which contains neutrons and protons.

Neutron  A particle with no charge found in the nucleus of atoms.

Particle  A minute, or tiny, portion of matter.

Periodic Table  A table that lists the earth’s 118 elements in a specific order.

Proton  A particle with a positive charge found in the nucleus of atoms.

Pure Substance  Matter that always has the same composition.

Subatomic Particles  The tiny electrons, and more massive neutrons and protons, which make up atoms.