2. Ionic bonds are formed between metals and non metals – (opposite sides of the periodic table) Electrons are given (metals) or taken (non metals) Ex: CaCl 2 Covalent bonds are formed between elements on the left side of the stair step (usually 2 non metals). Electrons are shared in covalent bonds. Ex: CO 2 BONDING

3. Stable ionic bonds are formed when the sum of the oxidation numbers equals zero. Ca 2+ O 2- equal zero so CaO is stable if unequal, criss-cross Ca 2+ Cl 1- becomes CaCl 2 STABLE IONIC BONDS

4. Follow the formula D=m/V m is mass (grams), V is volume (mL or cm 3 ) Given – mass 20 grams, volume 10 mL 20 g/10 mL = 2 g/mL DENSITY

5. Isotopes are forms of element that have the same number of protons but a different number of neutrons. Oxygen-16 and Oxygen 18 are isotopes O-16 has 8 neutrons O-18 has 10 neutrons a As they are both oxygen, they both have 8 protons ISOTOPES

6. Families on the periodic table have the same number of valence electrons (outside electrons) Review these four major groups on the table Alkali metalsAlkaline Earth metals HalogensNoble Gases PERIODIC TABLE FAMILIES

7. Weight is due to gravity’s effect on mass. Weight can change as you get further away from the source of gravity (ex: Earth’s surface) Mass is the amount of matter contained in an object and does not change. WEIGHT VS. MASS

8. The state of matter defines the motion of molecules. Solids move the least, liquids move more and gases move the most. KINETIC THEORY OF MATTER

9. If there are relationships described in a situation that need some form of calculation, always look for a formula. LOOK FOR FORMULAS

10. 1 st Law – Inertia 2 nd Law – a=F/m 3 rd Law – Action-reaction forces NEWTON’S LAWS OF MOTION

11. Solubility describes how much solute can dissolve in a solvent. review Saturated Unsaturated Supersaturated SOLUBILITY