TAKS Review: ChemistryTAKS Review: Chemistry

Focus on basic properties of Focus on basic properties of matter!matter!

Physical PropertiesPhysical Properties

►Describe the physical nature of Describe the physical nature of matter, not its chemical behavior.matter, not its chemical behavior.

►Examples:Examples: Melting point, boiling point, freezing Melting point, boiling point, freezing

points, color, viscosity, density . . .points, color, viscosity, density . . . Melting and boiling points along with Melting and boiling points along with

density are ways of identifying unknown density are ways of identifying unknown substancessubstances

Chemical PropertiesChemical Properties

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

Physical and Chemical Physical and Chemical ChangesChanges

►Rotting, burning, cutting in half, Rotting, burning, cutting in half, vaporizing, rusting, explodes …..vaporizing, rusting, explodes …..

►So, which of the above are physical So, which of the above are physical changes and which are chemical?changes and which are chemical?

►Ask, which of the above changes the Ask, which of the above changes the essence of the matter?essence of the matter?

►Exploding is chemical, why? It’s a Exploding is chemical, why? It’s a reaction!reaction!

►Cutting in half? Physical; it’s still the Cutting in half? Physical; it’s still the same stuff.same stuff.

Evidences of a chemical Evidences of a chemical change!change!

►Precipitates = solids formed when 2 Precipitates = solids formed when 2 clear liquids mix.clear liquids mix.

►Gas given offGas given off►Color change (be careful, can be Color change (be careful, can be

physical only, but a color change often physical only, but a color change often accompanies a chemical one).accompanies a chemical one).

►Heat (exothermic or endothermic).Heat (exothermic or endothermic).►Light.Light.

Exo or EndoExo or Endo

► Heat = - 510 kilojoulesHeat = - 510 kilojoules► Heat = +510 kilojoulesHeat = +510 kilojoules

► If Heat is +, it’s endothermic (Temp. If Heat is +, it’s endothermic (Temp. drops)drops)

► If Heat is -, it’s exothermic(Temp. If Heat is -, it’s exothermic(Temp. increasesincreases

Density vs. WeightDensity vs. Weight

►What’s the difference between density What’s the difference between density and weight? Which changes if you and weight? Which changes if you suddenly land on the moon?suddenly land on the moon?

►Weight! Density is a ratio of your Weight! Density is a ratio of your mass to volume which shouldn’t mass to volume which shouldn’t change if you made it safely.change if you made it safely.

► If a block of wood is cut in half, how If a block of wood is cut in half, how does that change the density?does that change the density?

► It doesn’t!!It doesn’t!!

ViscosityViscosity

► Thickness of a liquid based on bonding. Thickness of a liquid based on bonding. ► Syrup is more viscous than water because of Syrup is more viscous than water because of

the cohesive bonding of the molecules.the cohesive bonding of the molecules.► How would you measure the viscosity of a How would you measure the viscosity of a

liquid? Drop a marble in it and time it.liquid? Drop a marble in it and time it.► I know, it sounds stupid, but we’re trying to I know, it sounds stupid, but we’re trying to

pass the test.pass the test.► The longer it takes for the marble to reach The longer it takes for the marble to reach

the bottom in equal amts., the more viscous.the bottom in equal amts., the more viscous.

Review Your Periodic TableReview Your Periodic Table

• Know the difference between a Group Know the difference between a Group and a Period.and a Period.

• Groups, vertical. Group I has Li and Na Groups, vertical. Group I has Li and Na which have similar properties because which have similar properties because they have 1 valence electron and form they have 1 valence electron and form +1 ions to achieve a stable octet.+1 ions to achieve a stable octet.

• Periods, horizontal. Have same outer Periods, horizontal. Have same outer energy levels. 4energy levels. 4thth Pd = 4 Pd = 4thth outer level. outer level.

Parts of the TableParts of the Table

• Transition metals/Alkali metalsTransition metals/Alkali metals• HalogensHalogens• Noble gases; what’s special about them?Noble gases; what’s special about them?• Calcium will form what kind of ion with Calcium will form what kind of ion with

what magnitude of charge?what magnitude of charge?• 2+2+• Chlorine ?Chlorine ?• 1-1-• Formula?? CaClFormula?? CaCl22

3 states of Matter3 states of Matter

SolidsSolids LiquidsLiquids GasesGases Describe the molecular motion for each state.Describe the molecular motion for each state. What is the relationship between the strength What is the relationship between the strength

of the bonding and matter’s physical state?of the bonding and matter’s physical state? Stronger bonds tend to form solids.Stronger bonds tend to form solids.

Types of BondsTypes of Bonds

Ionic = metal and non-metalIonic = metal and non-metal Na+ + Cl- Na+ + Cl- NaCl NaCl

Covalent = sharing e’s; non-metals.Covalent = sharing e’s; non-metals. H – Cl H – Cl share 1 pr. of e’s.share 1 pr. of e’s.

Ionic – crystalsIonic – crystals Covalent – some solids, liquids and gases.Covalent – some solids, liquids and gases. Gases tend to be non-polar covalent. Gases tend to be non-polar covalent.

Balancing Equations

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- = MgCl2 magnesium chloride

Mg+2 + PO4 -3 Mg3(PO4)2 magnesium phosphate

So, put it together

KClO3 KCl + O2

2,2,3 H2 + O2 H2O 2,1,2

Kinetic Energy and atoms

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?

Law of Conservation of Mass

Mass of Reactants = Mass of Products 2H2 + O2 2 H2O

11 g. ? 23 g. 11 + ? = 23 then ? = 12 grams!

3 forms of Matter3 forms of Matter

ElementsElements: the purest form of matter.: the purest form of matter.

* Check the periodic table.* Check the periodic table. CompoundsCompounds: combinations of elements : combinations of elements

in a specific ratio ( water is Hin a specific ratio ( water is H220, not 0, not

HH220022).).

MixturesMixtures: compounds and elements : compounds and elements tossed together in any proportion.tossed together in any proportion.

Mixtures: types of.Mixtures: types of.

HomogenousHomogenous: the mixture looks the : the mixture looks the same throughout.same throughout.

- kool aid, salt water, milk . . - kool aid, salt water, milk . . HeterogeneousHeterogeneous: mixture maintains : mixture maintains

separate parts.separate parts.

- rocks and water, dirt.- rocks and water, dirt.

Solutions: Solutions: a type of mixturea type of mixture

Made of a Made of a solutesolute (what gets dissolved) (what gets dissolved) and a and a solventsolvent (what does the dissolving). (what does the dissolving).

Homogeneous and Heterogeneous Homogeneous and Heterogeneous solutions. See last slide.solutions. See last slide.

Water is always the solvent, salt is a Water is always the solvent, salt is a solute.solute.

Unsaturated, saturated and super-Unsaturated, saturated and super-saturatedsaturated solutions. solutions.

Acids & BasesAcids & Bases

Solutions can be acidic or basic.Solutions can be acidic or basic. Acid solutions taste sour, Basic Acid solutions taste sour, Basic

solutions taste bitter. Lemon vs. Soap.solutions taste bitter. Lemon vs. Soap. pH is a scale used to identify weak pH is a scale used to identify weak

solutions as either acidic or basic.solutions as either acidic or basic. 7(neutral)7(neutral)

0 Acidic0 Acidic Basic Basic 1414

Types of Acids/BasesTypes of Acids/Bases Acids: hydrochloric acid (HCl) is a Strong acidAcids: hydrochloric acid (HCl) is a Strong acid Organic acids like citric or vinegar are weak Organic acids like citric or vinegar are weak

acids.acids. Strong base solutions are often called alkaline or Strong base solutions are often called alkaline or

caustic.caustic. If a solution has a pH of 10, it’s basic and would If a solution has a pH of 10, it’s basic and would

require vinegar, maybe, added to it to bring the require vinegar, maybe, added to it to bring the pH down. That’s why they put citric acid in your pH down. That’s why they put citric acid in your shampoo which is normally basic because it’s a shampoo which is normally basic because it’s a soap down to 5.5 which is the pH of your hair.soap down to 5.5 which is the pH of your hair.

WaterWater

Acids are made of Acids are made of HydroniumHydronium ions ions (H(H33O+) in water.O+) in water.

Bases are made of Bases are made of HydroxideHydroxide ions (OH-) ions (OH-) in water.in water.

Water is neutral, a pH of 7, because the Water is neutral, a pH of 7, because the number or concentration of Hnumber or concentration of H33OO++s = OHs = OH--

s.s. HH33OO++ + OH + OH-- 2 H 2 H22O (neutral)O (neutral)

acid baseacid base