2. Matter- the stuff that makes up everything in the universe Element- A substance that cannot be broken down into other substances by chemical or physical means Compound- A substance made of two or more elements chemically combined Mixture- Two or more substances that are mixed together but not chemically combined Atom- The smallest particle of an element Molecule- A combination of two or more atoms that are bonded together

3. ATOMS = BUILDING BLOCKS Atoms are the basis of chemistry. They are the basis for everything in the Universe.

4. There are three basic parts of an atom. The parts are the electrons, protons, and neutrons. The protons and neutrons are always in the center of the atom. Scientists call the center of the atom the nucleus. The electrons are always found whizzing around the center in areas called orbitals.

5. Draw in your notebook

6. This is a Bohr Model of an atom.

7. The atom is made up of three parts: Proton(+)- Small, positively charged particles in the nucleus of an atom Neutron(0)- Small uncharged particle in the nucleus of an atom Electron(-)- a tiny, negatively charged, high-energy particle that moves in the space outside the nucleus of an atom

8. Atomic Number The number of protons in the nucleus of an atom The identity of an atom is determined by the Atomic # Helium has 2 Protons, its atomic number is 2

9. The Periodic Table Atomic Number

10. Atomic weight

11. How to find the # of Protons, Neutrons, & Electron Protons-Same amount as the atomic # Electrons- Same as the # of protons Neutrons- The atomic mass – the atomic #

12. Na Sodium 23 Protons: 11 Neutrons: 12 Electrons: 11 11

13. Atomic Mass The average mass of one atom of an element

14. Valence Electrons The number of electrons in the outermost orbit of an atom

15. Isotope An atom with the same number of protons and different number of neutrons (and therefore different atomic masses) Example: Carbon -12 Carbon -14

16. Examples of Carbon Isotopes