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Class TAKS Review Objective 4

Matter and Change

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Matter• Anything

that has mass and takes up space.

• Energy is NOT matter

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Matter is divided into 3 types:

• Elements

• Compounds

• Mixtures

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Atoms are. . .

• The smallest part of a single element.

• The basis of all matter. • Made of mostly empty

space. • Have a positive core or

nucleus. • Have electrons in orbit in

clouds.

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4 Basic Types of Elements

• Metals: found on the left and center of the Table of Elements

• Non-metals: found on the right side of the Table of Elements

• Metalloids: found along the stair-step line

• Synthetic: made in the laboratory and not yet found in nature – many of the Actinide and Lanthanide series and very large # elements.

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Where are the metal elements?

Left of the Stair-step line!

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Properties of Elements - Metals

• Metals are: –Conductors

–Lustrous

–Electron donors

–Malleable

–Ductile

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Where are the nonmetals? To the Right of the stair step line, and Hydrogen!

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Properties of Nonmetals

• Nonmetals are brittle, insulators, electron acceptors

• Usually form negative ions (except H)

• Many are gases at room temperature

• Found to the right of the stair-step line

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According to the periodic table, which element most readily accepts electrons?

• A Fluorine• B Nitrogen • This is a nonmetal, so it

accepts electrons but it will also share them as in NO3

1-.• C Arsenic • This is a metalloid, so it only

sometimes accepts electrons.• D Aluminum • This is a metal so it donates

electrons.

Fluorine only needs 1 electron to complete its shell of 8, so it will accept it from any other element very very very easily. This periodic property increases as you move up and left in the table, except for the Noble Gases.

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The BOHR Model of an Atom

• This is the first model to have a nucleus with protons and neutrons.

• The electrons are in various energy levels and circle the nucleus.

• Model most people draw today.

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Use the Table provided! What do the numbers mean?

Na

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22.990

sodium

This is the atomic number. It is the number of protons in a single atom of this element. By the way, its also # of electrons.

The symbol for this element.

This is the atomic mass, it is the number of protons + neutrons, or the mass of the nucleus of an atom.

This is the name of the element.

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Diatomic Elements – Nonmetals that come as molecules

• 7 Elements are di- (2) atomic (atoms)

• The easy way to remember them is by the name

•Br I N Cl H O F

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

A Li, Be, C

B Be, Mg, Sr

C Sc, Y, Zr

D C, N, O

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Lets look at the Table provided.• To have similar

chemical properties of any kind, they must be in the same Group or Family.

• Groups are columns, so the answer would be

• B

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Chemical Reactivity • Metals increase

in reactivity left and down.

• Nonmetals become more reactive up and to the right.

• Most reactive metal is?

• Most reactive nonmetal is?

Fr

F

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Names of Compounds – Ionic

• Ionic compounds consist of cations (positive ions) and anions (negative ions).

• A Roman numeral in parentheses, preceded by the name of the element, is used for elements that can form more than one positive ion. This is usually seen with metals.

• Fe2+ Iron (II) Cu+ Copper (I)Fe3+ Iron (III) Cu2+ Copper (II)

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Changes in Matter – Physical or Chemical?

• Physical changes are changes in the state of matter. They do not change the substance. (Melting, boiling, condensing, freezing, cutting)

• Chemical changes are reactions that result in new products with new properties.

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Changes in Matter – Physical, Chemical?

• Physical changes do not change the substance. The state of the matter may change, but it keeps its own properties.

• Cutting a piece of wood does not change the wood, it is simply smaller.

• Chemical changes are also called chemical reactions.

• When a different substance is produced than what was present at the start, a chemical change has occurred.

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Nuclear: Fission and Fusion

• Fusion occurs when the nucleus of one atom is joined by the nucleus of another.

• This is the reaction that occurs on the sun and stars.

• It produces extreme energy release.

• Fission occurs when the nucleus of an atom ejects particles and energy when hit by a subatomic particle such as a neutron.

• This also causes a release of extreme energy and is the basis of atomic energy plants and bombs.

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Density = Mass / Volume THIS IS FROM THE FORMULA PAGE25 A block of maple wood with a volume of405 cubic centimeters and a density of0.67 g/cm3 is sawed in half. The densityof the two smaller blocks is now —A one-fourth the original densityB one-half the original densityC two times the original densityD the same as the original density

If the block is cut in half, you cut the mass in half AND you cut the volume in half, so Mass/2 or Volume/2

Mass x 2 (which is really 1) so . . . .

Volume 2

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20 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 of the sample? Record and bubble in your answer to the nearest tenth on the answer document.

Use the formula page, D = M/V

1.85 g/mL =

Multiply both sides by 78.0 mL and you get:

144.3 g Grid it in!

mL 78.0

x

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Viscosity

• Viscosity is resistance to fluid flow.

• When particles in a liquid are strongly

attracted there is high viscosity.

• When particles in a liquid are weakly

attracted there is low viscosity.

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Viscosity

• What about when you heat up syrup? Then it seems to flow faster. What’s going on then?

•When you warm up a substance the kinetic energy of the molecules increase. This means that the molecules are moving faster, weakening the attraction between the particles, and lowering the viscosity.

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Law of Conservation of Mass

• Matter can not be created or destroyed. • The total mass of the substances before they

react is equal to the total mass after they react.

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Chemical Reactions Since matter can not

be created or destroyed, chemical reactions must be balanced in terms of mass.

The amount of mass you start with must be equal to the mass of the products.

Reactants Products

100g total = 100g total

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39 According to the law of conservation of mass, how much zinc was present in the

zinc carbonate?

A 40 g B 88 g C 104 g D 256 gSince matter can not be created or destroyed in chemical reactions, the mass on both sides of the arrow must be equal. So 64g + 192g = 256g and 152 g + Zinc = 256g

There must be 104g of Zinc. Answer C.

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Chemical Equations• Whole numbers written in front of formulas are

called coefficients. For example, 4 C6H12O6 indicates that there are 4 molecules of glucose sugar.

• To determine how many total atoms of each element are present, multiply the coefficients by the subscripts for each element.

• 4 C6H12O6 would contain 24 atoms of carbon

(4 x 6), 48 atoms of hydrogen (4 x 12), and 24 atoms of oxygen (4 x 6).

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To balance equations: • The number of atoms of each type of element

on the reactant side (left of the arrow) must be equal those on the product side (right side of the arrow).

2 H2 + O2 2 H2O

• There are 4 hydrogen atoms on the left (2 H2) and 4 hydrogen atoms on the right (2 H2O)

• There are 2 atoms of oxygen (O2) on the left and 2 atoms of oxygen on the right (2 H2O). When a subscript is missing, it is understood to be 1.

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K + H2O KOH + H2

What is the coefficient for H2O when the above equation is balanced?

• A 1

• B 2

• C 3

• D 4

To balance this equation, make water HOH, then you will see that you need 2 H and get 2 OH groups.

That means the KOH gets a coefficient of 2, the K gets a coefficient of 2 and

The water must also get a coefficient of 2.

H OH 22 2

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Balance the equation below, the boxes should get the coefficients.

Which element does not have the same number of atoms on both sides? Oxygen. It has 2 on the reactant side and 3 on the product side. If we put a coefficient of 2 in front of PbO, we will now have 4 O and 2 Pb on the right. By placing a coefficient of 2 in front of the reactant, we have 2 Pb and 2 x 2 O. That means it is balanced! Answer?

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C

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P r o p e r t i e s o f M i x t u r e s :P r o p e r t i e s o f M i x t u r e s :

• E a c h s u b s t a n c e r e t a i n s i t s o w n p r o p e r t i e s .

• S u b s t a n c e s c a n b e p r e s e n t i n a n y a m o u n

t . • S u b s t a n c e s c a n b e

s e p a r a t e d b y s i m p l e p h y s i c a l m e a n s.

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There are two types of mixtures:

• Heterogeneous-Heterogeneous- mixture is not the mixture is not the same from place to same from place to place. place. – Chocolate chip Chocolate chip

cookie, gravel, soil. cookie, gravel, soil.

• Homogeneous-Homogeneous- same same composition throughout. composition throughout.

– Kool-aid, air, brass. Kool-aid, air, brass.

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Separating Mixtures – Physical Changes

• Separation of mixtures could be:

• Magnetic removal (if there is Fe, Ni, Co)

• Filtration (if there are large particles)

• Hand sorting particles • Decanting (pouring off

the less dense liquid)

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Another technique for separating mixtures:

Evaporation: changing from

a liquid to vapor state– leaves behind the other

component.

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Distillation:– Process used to

remove vapor from liquid by heating

– Great for separating two or more liquids which have different boiling points.

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Solutions:Solutions:–S o l v e n t - t h e m o s t

a b u n d a n t s u b s t a n c e i n t h e s o l u t i o n .

–S o l u t e - t h e l e a s t a b u n d a n t s u b s t a n c e i n t h e s o l u t i o n .

– Homogeneous: You can not see any particles of either part!

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The three methods to increase the rate of solution for a solid

are?

•Heat it!

•Crush it! •Stir it!

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17 All of these can affect the rate at which a solid dissolves in water except —

A decreasing air pressure

B stirring the water

C increasing the temperature of the water

D using larger crystals of the solid

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The three methods to increase the rate of solution for a solid are?

• Heat it! C

• Crush it! D slows it

• Stir it! B

• So this eliminates choices B, C & D

• Which will NOT change it?

• A

Answer choices were:

A decreasing air pressure

B stirring the water

C increasing the temperature of the water

D using larger crystals of the solid

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Solubility Factors – What will dissolve?

Solubility Rules• 1. All sodium, potassium, and ammonium salts are

soluble.• 2. All silver, lead, and mercury salts are insoluble.• 3. All carbonates, sulfides, and hydroxides are

insoluble.• 4. All nitrates and sulfates are soluble except

calcium sulfate and barium sulfate.

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10 A 0.2 g crystal of gypsum dissolves very slowly in 100 mL of water while the water is stirred. Which of these would cause the gypsum to dissolve faster?

F Decreasing the water temperature

G Stopping the stirring

H Lowering the air pressure

J Crushing the crystal

What are the 3 ways to increase the rate at

which a solid dissolves?

Heat it!

Crush it!

Stir it!

ANSWER?

J

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How much solute will dissolve?

• A solubility curve shows the amount of each solute that will dissolve in 100g H20 at each temperature.

• Saturated is on the line. • Unsaturated is below

the line. • Supersaturated is above

the line.

Gra

ms

solu

te/1

00 g

H2O

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51 At which temperature do KBr and KNO3 have the same solubility?

A 27°C

B 48°C

C 65°C

D 80°C

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Try this one!

49 According to the graph, about how muchhemoglobin would be saturated at an O2pressure of 7.3 kPa?A 32%B 67%C 89%D 92%

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I. Relate the Structure of Water to its Function as the Universal Solvent

• Most of chemistry is based on solution chemistry, where water is the solvent (called aqueous solutions).

Solutions—homogeneous mixture of two or more substances. The dissolved substance is completely dispersed, i.e., its composition is the same throughout its volume.

Usually a solid is dissolved in a liquid, but liquids can be dissolved in other liquids and gases can be dissolved in a liquid as well.

Solvent: the substance that dissolves a solute to form a solution. (ex: water)

Solute: the substance that dissolves in the solvent. (ex: salt)

Oceans are salt water solutions—water is the solvent, salt is the solute.

Sweet tea in another example — sugar is the solute and water is the solvent

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The Water Molecule• The water molecule is made up of one hydrogen

atom and two oxygen atoms.• This v-shaped molecule as a whole is electrically

neutral, yet the oxygen atom holds a small negative charge and the two hydrogen atoms hold small positive charges. This unusual electrical balancing is called polarity.

• Water's polarity means it dissolves most everything.

•Because water molecules have a positive side and a negative side, any atom with a positive or negative charge can bond with it.

Water is actively attracted to other molecules.

At the same time, other molecules are attracted to water molecules.

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Water as a solvent• The partial charge that develops across the water molecule helps

make it an excellent solvent. • Water dissolves many substances by surrounding charged particles

and "pulling" them into solution. • For example, common table salt, sodium chloride, is an ionic

substance that contains alternating sodium and chlorine ions. • When table salt is added to water, the partial charges on the water

molecule are attracted to the Na+ and Cl- ions.

-

++

-

++

The water molecules work their way into the crystal structure and between the individual ions, surrounding them and slowly dissolving the salt. The water molecules will actually line up differently depending on which ions are being pulled into solution. The negative oxygen ends of water molecules will surround the positive sodium ions; the positive hydrogen ends will surround the negative chlorine ions.

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pH is a measure of the Strength of Acids & Bases

• Acids have 0-6.99 pH• Bases have 7.01-14 pH• Remember because A

begins the alphabet and zero begins numbers

• Litmus turns red in acids and blue in bases

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Higher pH levels means?33 Two clear solutions are placed in separate

beakers. The first solution has a pH of 4, and the pH of the second solution is unknown. If

the two solutions are mixed and the resulting

pH is 5, the second solution must have —

A fewer suspended solids

B a lower temperature

C more dissolved salt (NaCl) particles

D a higher concentration of OH– ions

Solutions are homogeneous and have no suspended solids. Nothing is mentioned about temperature so B is invalid. NaCl solutions are neutral so have no effect on pH.

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Acids and BasesAcids are compounds that add H+ ions to water when in a solution.

HCl (Hydrochloric acid) is a very strong acid.

In water it breaks up

(dissociates) and

adds H+ ions.

Many of our foods are acidic: citric (lemons; oranges); apples; tomato sauce.

Acids taste sour and feel “squeaky” when you rub your fingers together.

Bases are compounds that add OH- ions towater when in a solution.

NaOH (sodium hydroxide):a very strong base.

In water it breaks up (dissociates) adding OH– ions to the water.

Many of our cleaning products are basic: ammonia (Windex); soap;bleach.

Bases taste bitter and feel slippery.

Strong acids and bases —ionize almostcompletely in water, contributing many ions.Strong acids and bases can burn your skin or eyes.(concentrated hydrochloric acid, drain cleaner)

Weak acids and bases—ionize incompletely, contributing just a few ions. (Vinegar, baking soda)

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pHMeasure of acids and bases

Litmus paper turns red in acids and blue in bases

Phenothalein turns pink in a base and stays clear in acids.

Neutralization(Titration)

When acids and bases are mixed they neutralize each other. If an equal concentration of acid and base are mixed they make neutral salt water.

Typical neutralization reaction

HCl + NaOH → H2O + NaClAcid + Base → Salt Water

“Neutralize that stomach acid” with anantacid—a base! Antacids are just bases.

H+ ions OH- ions