2 What is a molecule? Groups of atoms tightly bonded by covalent bonds Examples water, oxygen, carbon dioxide
3 Rule of Charges Opposites always attract Like always repel Atoms arrange themselves based on these two rulese.g. Na+ will tend to attract to Cl-, but Na+ tends to push away other Na+ ions
4 Ionic BondsCharges are easily determined in ionic bonds…you’ve already done it….-atoms with 3 or more valence electrons want to lose, therefore they are +-atoms with 5 or more valence electrons want to gain, therefore they are –Na+ Cl-
5 Covalent Bonds More difficult to determine charge Many do not have a chargeThese are called NONPOLAR moleculesThey share valence electrons equallye.g. all the diatomic elements
6 Polar Molecules Comes from the word “pole” like on a magnet -opposite ends of a molecule have opposite charges.*Some atoms pull shared electrons harder than other…this property is called electronegativity*Fluorine pulls the hardest, then chlorine and oxygen.
7 Polar MoleculesAtoms that pull the hardest on the electrons have more of a negative chargeAtoms that pull the least on the shared electrons have more of a positive charge
8 The ability of Polar Molecules Polar molecules have the ability to dissolve ionic bonds because of the charges of the ends of the covalent molecules.Water = red & white, Chlorine = green, Sodium = orange
9 SolubilityA measure of how well a substance dissolves in another substanceSolvent- substance in the larger amount; does the dissolvingSolute- substance in smaller amount; is dissolvedIn salt water—Salt is the solute, water is the solvent.
10 What makes something soluble? Salt mixes with water, oil does not.What is the difference?Remember our rule of charges:Opposites will _________________Like will _______________
11 Solute/Solvent Relationships The rule of whether or not something will dissolve is simple:Like Dissolves LikeA Polar molecule will dissolve another polar molecule (salt and water)A nonpolar molecule will dissolve another nonpolar molecule (Nail polish and nail polish remover)
12 InsolubleSubstances that do not dissolve (like oil and water) are considered insolubleOil is nonpolar—(has no charge at all)Water is polar—(has a positive and negative end)The water is attracted to itself more than to the oil so they will not mix.
13 What thing affect solubility? Polarity/Nonpolarity is the main oneTemperature IncreaseAs things warm molecule movement increasesMakes things more likely to mixPressure IncreaseAs things get pushed together
14 Saturated vs. Unsaturated All substances can only mix so much.Once you put so much salt in water, that solution will not accept any more salt.-It is said to be SATURATEDBefore it reaches that point, those water particles can still accept more salt, so it is said to be UNSATURATED
15 Soaps and DetergentsHow do soaps and detergents work on everything or do they?There seems to be a cleaning agent for everything.Soaps and detergents have both polar and nonpolar parts, so they are able to dissolve either kind of dirt and grime.