2. Matter- anything that has mass and occupies space Atom- basic unit of matter Subatomic particles: Protons (+) –in nucleus, 1 amu Neutrons (0) –in nucleus, 1 amu Electrons (-) –in clouds or orbitals, 1/1840 amu, very very small *amu= atomic mass unit

3. Element- pure substance that consists entirely of one type of atom Compound –a substance containing two or more elements NaCl Isotopes- elements with differing number of neutrons in the nucleus Ex. Carbon -12, has 12 neutrons Carbon -13, has 13 neutrons Carbon -14, has 14 neutrons

4. Atomic Number - # of protons, equals # electrons in neutral atom Atomic Mass/ Mass Number- # of protons + # of neutrons Reading Periodic Table

5. Periodic Table Practice: ElementAtomic #Mass ## Protons# Neutrons# Electrons O168 C6126 Li73 P1531 Cl3517 Ne2010 Ni2831

6. Electron Energy Levels Electrons orbit nucleus at different distances, called energy levels 1 st level- closest to nucleus, holds 2 electrons 2 nd level- holds 8 electrons 3 rd level- holds 18 Valence electrons- electrons located in the outer level, atoms stable with 8 valence electrons

7. Electron Dot Diagrams Electron Dot Diagrams- only show valence electrons, electrons in outermost energy level

8. Why & How does Chemical Bonding Occur? Octet Rule- atoms gain/lose/share electrons with other atoms in order to become stable/ happy with 8 valence electrons Atoms gain/lose the least number of electrons as possible Ex. Sodium (Na)= 1 valence electron, will lose 1 electron instead of gain 7 electrons Ex. Chlorine (Cl)= 7 valence electrons, will gain 1 electron instead of losing 7 electrons

9. Ionic bonds Ionic bonds- when an atom transfers an electron to another atom

10. Ionic bonds Ion- atoms that have become electrically charged as a result of gaining or losing e- Cation- (+) charge, Ex. Na+ losing e- became 1+ Anion- (-) charge, Ex. Cl-, gaining e- became 1- Attraction holding Na+ and Cl- Ionic bond

11. Covalent bonds Covalent bond is when two atoms share electrons. The number of bonds an atom can form depend on the number of e- needed to fill its highest energy level. H- only 1 O – accepts 2 Molecules- atoms held together by covalent bonds

12. Water H 2 O