Focus on basic properties of matter!

 Describe the physical nature of matter, not its chemical behavior.  Examples:  Melting point, boiling point, freezing points, color, viscosity, density...  Melting and boiling points along with density are ways of identifying unknown substances

 Properties that describe the chemical behavior of matter.  Formation of cations (+) or anions (-).  Combines with oxygen or burns in air.  Anything related to reactivity.

WWhat’s the difference between density and weight? Which changes if you suddenly land on the moon? WWeight! Density is a ratio of your mass to volume which shouldn’t change if you made it safely. IIf a block of wood is cut in half, how does that change the density? IIt doesn’t!!

 Thickness of a liquid based on bonding.  Syrup is more viscous than water because of the cohesive bonding of the molecules.  How would you measure the viscosity of a liquid? Drop a marble in it and time it.  I know, it sounds stupid, but we’re trying to pass the test.  The longer it takes for the marble to reach the bottom in equal amts., the more viscous.

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 Rotting, burning, cutting in half, vaporizing, rusting, explodes …..  So, which of the above are physical changes and which are chemical?  Ask, which of the above changes the essence of the matter?  Exploding is chemical, why? It’s a reaction!  Cutting in half? Physical; it’s still the same stuff.

 Precipitates = solids formed when 2 clear liquids mix.  Gas given off  Color change (be careful, can be physical only, but a color change often accompanies a chemical one).  Heat (exothermic or endothermic).  Light.

 Heat = kilojoules  Heat = +510 kilojoules  If Heat is +, it’s endothermic (Temp. drops)  If Heat is -, it’s exothermic(Temp. increases

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 Know the difference between a Group and a Period.  Groups, vertical. Group I has Li and Na which have similar properties because they have 1 valence electron and form +1 ions to achieve a stable octet.  Periods, horizontal. Have same outer energy levels. 4 th Pd = 4 th outer level.

TTransition metals/Alkali metals HHalogens NNoble gases; what’s special about them? CCalcium will form what kind of ion with what magnitude of charge? 22+ CChlorine ? 11- FFormula?? CaCl 2

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 Solids  Liquids  Gases  Describe the molecular motion for each state.  What is the relationship between the strength of the bonding and matter’s physical state?  Stronger bonds tend to form solids.

 Ionic = metal and non-metal  Na+ + Cl-  NaCl  Covalent = sharing e’s; non-metals.  H – Cl share 1 pr. of e’s.  Ionic – crystals  Covalent – some solids, liquids and gases.  Gases tend to be non-polar covalent.

 First, write the correct “formula” for a compound if it’s not given.  Ca + O  CaO Ca +2 + O -2 = CaO so the charges =0  Mg +2 + Cl - = MgCl 2 magnesium chloride  Mg +2 + PO 4 -3  Mg 3 (PO 4 ) 2 magnesium phosphate

 KClO 3  KCl + O 2 22,2,3  H 2 + O 2  H 2 O 22,1,2

 The More KE atoms have, the more they move.  Bonding holds them together  Gases have little bonding, so adding more heat (Kinetic Energy) causes them to move a lot.  Gas molecules moving around eventually cause collisions which create gas “pressure” inside a container.  Increase the temperature (KE) and the gas pressure increases. Why?

MMass of Reactants = Mass of Products  2H 2 + O 2  2 H 2 O 11 g. ? 23 g. 111 + ? = 23 then ? = 12 grams!

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 Elements  Elements: the purest form of matter. * Check the periodic table.  Compounds 2  Compounds: combinations of elements in a specific ratio ( water is H 2 0, not H ).  Mixtures  Mixtures: compounds and elements tossed together in any proportion.

 Homogenous: the mixture looks the same throughout. - kool aid, salt water, milk..  Heterogeneous: mixture maintains separate parts. - rocks and water, dirt.

 Made of a solute (what gets dissolved) and a solvent (what does the dissolving).  Homogeneous and Heterogeneous solutions. See last slide.  Water is always the solvent, salt is a solute.  Unsaturated, saturated and super-saturated solutions.

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 Solutions can be acidic or basic.  Acid solutions taste sour, Basic solutions taste bitter. Lemon vs. Soap.  pH is a scale used to identify weak solutions as either acidic or basic. 7(neutral) 0 Acidic Basic 14

 Acids: hydrochloric acid (HCl) is a Strong acid  Organic acids like citric or vinegar are weak acids.  Strong base solutions are often called alkaline or caustic.  If a solution has a pH of 10, it’s basic and would require vinegar, maybe, added to it to bring the pH down. That’s why they put citric acid in your shampoo which is normally basic because it’s a soap down to 5.5 which is the pH of your hair.

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 Acids are made of Hydronium ions (H 3 O+) in water.  Bases are made of Hydroxide ions (OH-) in water.  Water is neutral, a pH of 7, because the number or concentration of H 3 O + s = OH - s.  H 3 O + + OH -  2 H 2 O (neutral) acid base

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