1. Chapter 6 Bonding, Mixtures, and pH

2. What do atoms make up? ELEMENT: a substance made up of the same atoms – i.e. oxygen (O), gold (Au), carbon (C), COMPOUND: a substance formed by the bonding of two or more elements – i.e. Water (H 2 O) – i.e. Glucose (C 6 H 12 O 6 ) Gold is an element Sugar is a compound

3. How do atoms stay together? Valence Electrons: those in outermost shell – The only electrons involved in bonding 1) COVALENT BOND: 2 atoms that share valence electrons (STRONG!) – Ex. Oxygen (O 2 )

4. How do atoms stay together? 2) IONIC BOND: the attraction between 2 oppositely charged ions (WEAKER) One ion transfers a valence electron to another ion i.e. NaCl (Na+ and Cl - )

5. Chemical Reactions Involve the breaking and formation of bonds between atoms –R–Reactant: left side; is “rearranged” to form product –P–Product: right side; new element or compound formed –2–2H + O → H 2 O –R–Reactant → Product

6. Activation Energy Most reactions need added energy to get going Activation Energy: the amount of energy needed to start a reaction – Usually very high Catalyst: substance that decreases the amount of activation energy needed – Enzyme: important catalyst in organisms

7. Mixtures Solution: a mixture in which all components are evenly distributed – Solute: substance being dissolved – Solvent: substance doing the dissolving – Concentration: amount of solute/solvent – Aqueous Solution: solution in which water is the solvent Suspension: mixture of non-dissolved substances

8. Warm Up Feb 26 What state of matter have a definite volume but not a definite shape? A. Solid B. Liquid C. Gas D. Plasma

9. The pH Scale Measures the amount of hydrogen ions (H + ) in a solution Ranges from 0 (acidic)→14 (basic) pH 7 = neutral (water) –#–# H + ions = # OH - ions

10. Acids Solution with more Hydrogen ions (H+) Have sour taste May be corrosive Have pH of 0→6

11. Bases Solution with more Hydroxide ions (OH-) Have bitter taste Feel slippery Have pH 8→14