Objective 4Objective 4

►The student will demonstrate an The student will demonstrate an understanding of the structures and understanding of the structures and properties of matter.properties of matter.

3 overarching TEKS3 overarching TEKS

► IPC(7) The student knows relationships IPC(7) The student knows relationships exist between properties of matter and exist between properties of matter and its components.its components.

► IPC(8) The student knows that changes IPC(8) The student knows that changes in matter affect everyday life.in matter affect everyday life.

► IPC(9) The student knows how solution IPC(9) The student knows how solution chemistry is a part of everyday life.chemistry is a part of everyday life.

7(A)7(A)► Density: The amount of Density: The amount of mattermatter per given per given space space

(volume).(volume). The formula to calculate density is The formula to calculate density is D = D = mass/volumemass/volume and is found on the formula chart. The and is found on the formula chart. The density of an object density of an object does notdoes not change by changing the change by changing the volumevolume. Solids are more dense than liquids and liquids are . Solids are more dense than liquids and liquids are more dense than gases.more dense than gases.

► Viscosity: The Viscosity: The resistanceresistance of fluids to flow. Thick fluids of fluids to flow. Thick fluids flow flow slowerslower than thin ones do. Oil flows more than thin ones do. Oil flows more slowly slowly than water, thus, oil is more viscous than water.than water, thus, oil is more viscous than water.

► Buoyancy: The Buoyancy: The forceforce with which a more dense fluid with which a more dense fluid pushes a less dense substance pushes a less dense substance upward.upward. The student The student will have to compare the densities of two substances will have to compare the densities of two substances and will need to know that the more dense substance and will need to know that the more dense substance will be below the less dense. You will have to know will be below the less dense. You will have to know that the density of water is that the density of water is 1 1 g/cm3 .g/cm3 .

►1) 1) A sample of an element has a volume of A sample of an element has a volume of 78.0 mL and a density of 1.85 g/mL. What is the 78.0 mL and a density of 1.85 g/mL. What is the mass in grams of the sample? Record your mass in grams of the sample? Record your answer to the nearest tenth.answer to the nearest tenth.

►a.a.What does 78.0 represent? What does 78.0 represent? Mass volume density temperatureMass volume density temperature

► b. What does 1.85 represent? b. What does 1.85 represent? Mass volume density temperatureMass volume density temperature

► c. What is the question asking you to calculate? c. What is the question asking you to calculate? Mass volume density temperatureMass volume density temperature

Cont. problemCont. problem► 1) 1) A sample of an element has a volume of 78.0 mL A sample of an element has a volume of 78.0 mL

and a density of 1.85 g/mL. What is the mass in grams and a density of 1.85 g/mL. What is the mass in grams of the sample? Record your answer to the nearest of the sample? Record your answer to the nearest tenth.tenth.

► d. What formula will you use from the formula sheet?d. What formula will you use from the formula sheet?

► e. Substitute numbers from the problem into the e. Substitute numbers from the problem into the formula?formula?

► f. Calculate the unknown to the nearest tenth.f. Calculate the unknown to the nearest tenth.

D =Mass

volume

1.85 g/mL78.0 mL

mass

144.3 g

=

Another questionAnother question

6) 6) The picture shows the results of pouring The picture shows the results of pouring a blue liquid into a clear liquid and a blue liquid into a clear liquid and allowing the mixture to settle for 25 allowing the mixture to settle for 25 minutes. Compared to the clear liquid, minutes. Compared to the clear liquid, the blue liquid is more —the blue liquid is more —

►A A massivemassive►B B densedense►C C viscousviscous►D D solublesoluble See buoyancy notes.

7(D)7(D)► The periodic table organizes the elements into a grid of The periodic table organizes the elements into a grid of

horizontal rowshorizontal rows (left to right) called (left to right) called periods periods and vertical and vertical columns (up and down) called columns (up and down) called groupsgroups or families. or families.

► – – there are there are 1818 groupsgroups► - groups 1,2,13,14,15,16,17,18 have the pattern of - groups 1,2,13,14,15,16,17,18 have the pattern of

representing the number of representing the number of valence (outermost)valence (outermost) electronselectrons an atom of that element has; 1,2,3,4,5,6,7,8 an atom of that element has; 1,2,3,4,5,6,7,8 electrons, respectively.electrons, respectively.

► - - groups groups 1 & 21 & 2 want to want to loselose their total their total valance valance electronselectrons..

► - - groups groups 13-17 nonmetals13-17 nonmetals want to want to gain or accept extragain or accept extra electronselectrons to have a total of to have a total of 8 8 valence electrons. valence electrons.

► - - group 18group 18 does not loose or gain electrons, thus becoming does not loose or gain electrons, thus becoming non non reactivereactive..

► -elements in the same group have -elements in the same group have similarsimilar chemical and chemical and physical physical propertiesproperties because they have the because they have the samesame number of number of valance valance electrons.electrons.

7(D)7(D)

► The The zigzagzigzag line on the periodic table separates line on the periodic table separates metalsmetals from from nonmetalsnonmetals – elements to the right – elements to the right of the line are of the line are nonmetalsnonmetals and elements to the and elements to the left of the line are left of the line are metalsmetals..

► The The metalsmetals want to react with the nonmetals, want to react with the nonmetals, except group except group 18.18.

► -The -The formulas formulas for these compounds are for these compounds are written by balancing written by balancing charges.charges. The total The total positivepositive charge has to cancel the total charge has to cancel the total negativenegative charge. This can be accomplished by charge. This can be accomplished by the the drop drop and and swapswap method – drop the charge method – drop the charge and swap the number of the charge as a and swap the number of the charge as a subscript of the other element or ion.subscript of the other element or ion.

Ex ProblemsEx Problems

1 1 Which of the following groups contains members Which of the following groups contains members with similar chemical reactivity?with similar chemical reactivity?

A A Li, Be, CLi, Be, CBB Be, Mg, Sr Be, Mg, SrC C Sc, Y, ZrSc, Y, ZrD D C, N, OC, N, O2 According to this information, what is the chemical 2 According to this information, what is the chemical

formula for aluminum sulfate?formula for aluminum sulfate?A A AlSOAlSO44

B B AlAl22(SO(SO44))33

C C AlAl33(SO(SO44 ) )22

D D AlAl66 SO SO44

All in group 2

Drop and Swap

7(E)7(E)

► Element:Element: is a pure substance that is a pure substance that can notcan not be broken down into simpler substances.be broken down into simpler substances.

► Symbol form - Symbol form - “C”“C” for carbon, “Ni” for for carbon, “Ni” for nickel nickel *notice *notice oneone capital letter. capital letter.

► Word form – Word form – nitrogennitrogen, magnesium *, magnesium *wordswords found on the found on the periodic tableperiodic table

► You will need to be able to identify an You will need to be able to identify an atom from its model. atom from its model. Atomic Atomic number number represents represents number number of protons (+ charge)of protons (+ charge)

7(E)7(E)

► Compound: a combination of Compound: a combination of 2 2 or more or more elementselements that are that are combinedcombined chemically. chemically. There are two common compounds to There are two common compounds to memorize; water memorize; water (H(H22O)O) and table salt and table salt (NaCl).(NaCl).

► Symbol form – Symbol form – CaBrCaBr22 ; Mg(NO; Mg(NO33))22 *notice *notice twotwo or more or more capital letters.capital letters.

► Word form – Word form – calcium bromidecalcium bromide; magnesium ; magnesium nitrate *notice nitrate *notice twotwo elements names from elements names from the the periodic periodic table.table.

7(E)7(E)

► Mixture: two or more Mixture: two or more compoundscompounds and/or and/or elementselements together that are not chemically together that are not chemically combined.combined.

► stainless steelstainless steel – exact words – exact words not foundnot found on on the periodic table.the periodic table.

► Air Air – exact words not found on the periodic – exact words not found on the periodic table.table.

Ex QuestionsEx Questions► 1 1 An unknown silvery powder has a constant An unknown silvery powder has a constant

melting point and does not chemically or melting point and does not chemically or physically separate into other substances. The physically separate into other substances. The unknown substance can be classified as —unknown substance can be classified as —

A A an elementan elementB B a compounda compoundC C a mixturea mixtureD D an alloyan alloy► 2 2 The picture shows a model of the element —The picture shows a model of the element —A A fluorinefluorineB B heliumheliumC C berylliumberylliumD D oxygenoxygen

4 protons so look at atom number 4

8(A)8(A)► Chemical Change: A process that involves one Chemical Change: A process that involves one

or more substances changing into or more substances changing into new new substances.substances.

► Key words: Key words: explodeexplode, rust, oxidize, , rust, oxidize, corrode,corrode, tarnish, tarnish, ferment,ferment, burn, rot, burn, rot, reactsreacts

► Physical Change: A process that alters a Physical Change: A process that alters a substance substance without without changing its composition.changing its composition.

► Key words: bend, Key words: bend, grindgrind, crumple, split, , crumple, split, crush, melt, condense, crush, melt, condense, evaporateevaporate, boil, , boil, freeze.freeze.

► The questions on TAKS will be about the The questions on TAKS will be about the rock rock cyclecycle, , digestive systemdigestive system, changes in , changes in statestate (water freezing, evaporating, condensing), and (water freezing, evaporating, condensing), and oxidation (rusting, burning, decomposing). You oxidation (rusting, burning, decomposing). You will have to decide if the change is chemical or will have to decide if the change is chemical or physical.physical.

Ex. QuestionsEx. Questions► 1) Which of the following is an example of a chemical change?1) Which of the following is an example of a chemical change?A A Combustion of gasolineCombustion of gasolineB B An apple being bittenAn apple being bittenC C An ice cube being swallowedAn ice cube being swallowedD D Absorption of a water moleculeAbsorption of a water molecule

► 2 Which of the following processes is an example of a 2 Which of the following processes is an example of a physical change associated with an oak tree?physical change associated with an oak tree?

A Decomposition of bark by bracket fungiA Decomposition of bark by bracket fungiB Starches and sugars being broken down during energy B Starches and sugars being broken down during energy

productionproductionC Water and carbon dioxide being converted to glucoseC Water and carbon dioxide being converted to glucoseD Evaporation of water from the surfaces of leavesD Evaporation of water from the surfaces of leaves

8(C) Law of conservation of 8(C) Law of conservation of massmass

► There are two basic questions on TAKS on this TEK: There are two basic questions on TAKS on this TEK: 1) choosing a 1) choosing a balancedbalanced equation or balance one. equation or balance one. 2) making sure the 2) making sure the massmass of reactants equal the mass of reactants equal the mass

of of products.products.► BALANCING EQUATIONS:BALANCING EQUATIONS:► Let’s first review counting atoms in a chemical Let’s first review counting atoms in a chemical

formula.formula.► The numbers to the lower right of each chemical The numbers to the lower right of each chemical

symbol, called the symbol, called the subscriptsubscript, tells how many of , tells how many of those atoms make up the compound.those atoms make up the compound.

► If no number appears, then there is considered only If no number appears, then there is considered only oneone of those atoms. of those atoms.H2O

OH

H

8(C)8(C)

The numbers in front of the chemical formula The numbers in front of the chemical formula are called are called coefficientscoefficients and tell how many and tell how many compounds are represented.compounds are represented.

So So 44 hydrogens and hydrogens and 22 oxygens. You oxygens. You multiply multiply the coefficients by the the coefficients by the subscriptssubscripts for counting. for counting.

O

H HO

H H

2H2O

2 water molecules

Ex. ProblemEx. Problem

What are the coefficients that will balance this chemical equation?A 2, 1, 1B 3, 4, 2C 2, 2, 1D 4, 3, 2

Cont. 8(C) Law of conservation Cont. 8(C) Law of conservation of massof mass

►MASSES OF MASSES OF REACTANTSREACTANTS EQUAL TO EQUAL TO MASSES OF MASSES OF PRODUCTSPRODUCTS

►Remember that Remember that reactantsreactants are on the are on the left left side of the arrow and side of the arrow and productsproducts are are on the on the rightright side of the arrow.side of the arrow.

Ex. ProblemEx. Problem

According to the law of conservation of mass, how much zinc was present in the zinc carbonate?A 40 gB 88 gC 104 gD 256 g

64g + 192g = 152g + ?

9(A) Relate the structure of 9(A) Relate the structure of water to its function [as a water to its function [as a

universal solvent].universal solvent].► The water molecule (HThe water molecule (H22O) is a O) is a polar polar molecule – molecule –

meaning that one end of the molecule is meaning that one end of the molecule is slightly (δslightly (δ++) ) positivepositive and the other end is and the other end is slightly (δslightly (δ--) ) negative.negative.

► -the difference in -the difference in chargescharges allows the water allows the water molecule to surround charged particles and molecule to surround charged particles and thus thus dissolve dissolve them.them.

► The water molecule is also important because The water molecule is also important because its solid form (ice) is its solid form (ice) is less denseless dense than its liquid than its liquid form. Thus, ice form. Thus, ice floatsfloats on water to form a on water to form a protective protective insulationinsulation to prevent further to prevent further freezing.freezing.

Water molecules surrounding Water molecules surrounding ions.ions.Positive end of water (H)

Negative end of water (O)

Ex. ProblemEx. ProblemFish survive through severe winters because of the property of water that allows water to —F form chemical bonds as it freezes, raising the water temperature below the iceG increase in density while it freezes, dissolving more oxygen from the airH expand when it freezes, creating a floating and insulating layer of iceJ precipitate vital nutrients when it freezes, increasing the food supply

Water acts as a solvent of ionic compounds because —F water is liquid over a wide range of temperaturesG water molecules are polarH water is found in three states of matterJ water takes the shape of its container

9(B)9(B)relate the concentration of ions in a relate the concentration of ions in a solution to physical and chemical properties solution to physical and chemical properties such as pH, electrolytic behavior, and such as pH, electrolytic behavior, and reactivity.reactivity.► Concentration of ions is the Concentration of ions is the amountamount of ions of ions

per given per given volumevolume.. Concentration can be Concentration can be expressed as percent(%) solution.expressed as percent(%) solution.

► pH is the measure of pH is the measure of H+ ionsH+ ions in water. The in water. The “p”“p” in pH means in pH means powerpower,, so, pH means power so, pH means power of of H+ ionsH+ ions in solution. We have the pH scale in solution. We have the pH scale that is used to measure the that is used to measure the acidityacidity of of solutions. The higher concentration of solutions. The higher concentration of [H+][H+] the greater the the greater the acidityacidity, but can be confusing , but can be confusing when looking at the pH scale because when looking at the pH scale because lowerlower pH means more acidity. pH means more acidity.

► One cause of Acid rain is by burning One cause of Acid rain is by burning fossil fossil fuelsfuels..

This is pH. Notice as pH decreases, [H+] increases and becomes more acidic.

Electrolytic behaviorElectrolytic behavior

► ElectrolyticElectrolytic behavior of a solution is its ability to behavior of a solution is its ability to conduct conduct electricityelectricity. The more ions are dissolved in . The more ions are dissolved in water the greater the conduction of electricity. In water the greater the conduction of electricity. In the picture below, seawater has lots of salt the picture below, seawater has lots of salt dissolveddissolved in water making electricity flow through in water making electricity flow through it. it.

The greater the concentration of ions the brighter the light.

Ex. ProblemEx. Problem

The table shows data from an investigation designed to find a liquid solution that is both an acid and a strong electrolyte. Based on the data, a solution that is both an acid and a strong electrolyte is —A Solution 1B Solution 2C Solution 3D Solution 4

Bathwater normally has electrolytic Bathwater normally has electrolytic behaviors even though distilled water behaviors even though distilled water does not. This is because bathwater —does not. This is because bathwater —

►F F contains isotopes of hydrogencontains isotopes of hydrogen►G G has been heatedhas been heated►H H is separated into H+ and OH– ionsis separated into H+ and OH– ions►JJ contains dissolved minerals contains dissolved minerals

9(D)9(D) demonstrate how various factors influence demonstrate how various factors influence solubility including temperature, pressure, and nature solubility including temperature, pressure, and nature of the solute and solvent.of the solute and solvent.

► In most cases the In most cases the solvent solvent will be water and the will be water and the solute solute will be what ever is being dissolved. Some things do will be what ever is being dissolved. Some things do not dissolve and are thus called insoluble. Some not dissolve and are thus called insoluble. Some substances, compounds or elements, are more substances, compounds or elements, are more soluble than others. There are soluble than others. There are Solubility RulesSolubility Rules that that scientist follow but is not required to memorize for scientist follow but is not required to memorize for TAKS.TAKS.

► Several factors affect solubility for solids and gases. Several factors affect solubility for solids and gases. ► These are the factors for solids:These are the factors for solids:

increasingincreasing temperature of solvent (water) temperature of solvent (water) increases increases solubility.solubility.

crushingcrushing or or increasing increasing surface area surface area increasesincreases solubility. solubility. stirring or agitationstirring or agitation increases increases solubility. solubility. pressure pressure does notdoes not affect solubility of solids. affect solubility of solids.

9(D) cont.9(D) cont.

Notice the trend between solubility and temperature.

9(D) continue9(D) continue► Gases:Gases:

increasingincreasing temperature of solvent temperature of solvent decreases decreases solubility of gases. (heating a solubility of gases. (heating a can of soda makes it fizz)can of soda makes it fizz)

stirringstirring or agitation of solvent or agitation of solvent decreasesdecreases solubility of gases. (shaking a soda)solubility of gases. (shaking a soda)

increasingincreasing pressure of gas above solvent pressure of gas above solvent increasesincreases solubility – pushes gas into solubility – pushes gas into water.water.

►**Notice the relationship between temperature and Notice the relationship between temperature and solubility of gases in the table.solubility of gases in the table.

Ex. ProblemsEx. ProblemsPain medications can be made as powders or tablets. The powders tend to work faster than tablets with the same ingredients because powder —F dissolves faster in solution than a single tabletG has more total mass than a single tabletH travels through the bloodstream more easily than a tabletJ is easier to swallow than tablets

Over time an open soft drink will lose carbonation (dissolved CO2). Which of these allows the CO2 to remain in solution the longest?A Reduced air pressureB Exposure to direct sunlightC Increased air currentsD Cooler temperatures