1. Atoms and Elements

2. Subatomic Particles Atom- Smallest particle of an element. Subatomic Particles- Atoms are composed of protons, neutrons, and electrons. Nucleus- Small dense positively charged center of an atom. Proton- Subatomic particle that has a positive charge and is found in the nucleus of an atom. Electron- negatively charged subatomic particle found in an area outside the nucleus of an atom. Neutron- Subatomic particle with no electric charge that is found in the nucleus of an atom.

3. Atoms have their electrons arranged in layers called shells Atoms have their electrons arranged in layers called shells 1st level- 2 electrons max. 1st level- 2 electrons max. 2nd Level- 8 electrons max. 2nd Level- 8 electrons max. 3rd level- 18 electrons max. 3rd level- 18 electrons max. 4th level- 32 electrons max. 4th level- 32 electrons max.

4. Using the Periodic Table to understand makeup of atoms Atomic Number- Number of protons in the nucleus. Atomic Number- Number of protons in the nucleus. Atomic Mass- Average of the masses of the existing isotopes of an element. Atomic Mass- Average of the masses of the existing isotopes of an element. Mass number- the sum of the protons and neutrons in its nucleus. Mass number- the sum of the protons and neutrons in its nucleus.