Class TAKS Review Objective 4

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Matter and Change

Matter• Anything

that has mass and takes up space.

• Energy is NOT matter

Matter is divided into 3 types:

• Elements • Compounds• Mixtures

The 3 types can be further separated in two categories:

• Pure Substances

• Elements are the simplest pure substances

• Mixtures are not pure substances and we will deal with them tomorrow.

Compounds which are formed when two or more elements share electrons or become ions that attract other elements.

Cannot be broken down into simpler substances.

– All atoms of an element have the same number of protons.

– There are 109 of these currently listed and named on the Periodic Table

Elements:SIMPLIST KIND OF MATTER

4 Basic Types ofElements• 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.

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.

Drawing a Bohr Model of Lithium• Center (blue) circle

is the nucleus.• It should contain:

3+ and 4N to represent the 3 protons and 4 neutrons.

• The orange circle gets 2e-, and the purple gets 1e-.

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.

23 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.

What about MOLECULES?

These are MULTI-ATOM

particles

Properties of Elements - Metals

• Metals are: –Conductors –Lustrous –Electron

donors –Malleable –Ductile

Where are the metal elements?

Left of the Stair-step line!

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

Diatomic Elements – Nonmetals that come as

molecules

• 7 Elements are di- (2) atomic (atoms) • The easy way to remember them is by the

•Br I N Cl H O F

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

A Li, Be, CB Be, Mg, SrC Sc, Y, ZrD C, N, O

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

T y p e s o f m a t t e r• C o m p o u n d s -• Pure substances that can be

broken down by a chemical change.

• Molecules are the smallest particle of a compound that retains its properties and it is composed of 2 or more atoms.

When they are When they are broken down, the broken down, the pieces have pieces have completely different completely different properties than the properties than the compound. compound. Made of molecules- Made of molecules- two or more atomstwo or more atoms

Compounds:Compounds:Pure substances that can be broken Pure substances that can be broken

down by chemical methods down by chemical methods

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)

Ionic compounds – naming cont.

• The -ide ending is added to the name of a single element when it becomes an ion of that element. Oxide, Nitride, Sulfide etc.

Some polyatomic anions have a names ending in -ite for the lower # of oxygens and –ate for more oxygens.

NO2 nitrite NO3 nitrate

Covalent Compounds – Names are the Formulas

• These are nonmetal to nonmetal compounds.

• The name tells you the formula.

Carbon dioxide 1 C and 2 O

Special Names of Compounds Acids and Bases• Bases end in the

hydroxide anion OH-

• They are named with the metal and hydroxide.

• NaOH is sodium hydroxide

• Acids that are two elements are named Hydro-nonmetal –ic Acid such as – HCl hydrochloric acid

• Group -ate becomes –ic and -ite becomes –ous.

• H2SO3 sulfurous acid

• H2SO4 sulfuric acid

15 An advertisement claims that patients can be cured of the common cold in 48 hours by vitamin C tablets with secret mineral supplements. In a scientific experiment to test these claims, which data can be considered irrelevant?A The amount of vitamin C in each tabletB The severity of the patients’ cold symptomsC The chemical formula for vitamin CD The amount of time before symptoms improve

What doesn’t matter to the test?A The amount of vitamin C in each tablet This should be a controlled variable! B The severity of the patients’ cold symptoms This would be very hard to control, but a large

experimental group should allow for differencesC The chemical formula for vitamin C Compound formulas NEVER change so this is

our answer it is irrelevant!!! D The amount of time before symptoms improve This is what we are testing, it is most relevant.

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

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.

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/V1.85 g/mL =

Multiply both sides by 78.0 mL and you get:

144.3 g Grid it in!

mL 78.0x

Law of Conservation of Matter

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

are mixed is equal to the total mass as a mixture.

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

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.

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).

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.

K + H2O KOH + H2

19 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

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?

The 3 types can be further separated in two categories:

• Pure Substances

• Elements are the simplest pure substances

• Mixtures are not pure substances. Each part of a mixture keeps its own properties, and can be separated out by a physical change.

Compounds which are formed when two or more elements share electrons or become ions that attract other elements.

Decide if the substance is Element, Compound , or Mixture?

1. Water

2. Table Salt

3. Oxygen

4. Dirt

5. Air

1. Compound2. Compound

3. Element

4. Mixture

5. Mixture/Solution

Click Mouse button to see answers!

6. Copper

7. Soda

8. Steel

9. Rain

10. Ice-cream

6. Element7. Solution/Mixture

8. Solution/Mixture

9. Mixture

10. Mixture

Click Mouse button to see answers!

Let’s try a few more!

Changes in Matter – Physical, Chemical or Nuclear?

• 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.

Nuclear Changes: 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.

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.

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.

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)

Another technique for separating mixtures:

Evaporation: changing from

a liquid to vapor state– leaves behind the other

component.

Distillation:– Process used to

remove vapor from liquid by heating

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

So, what is a suspension or colloid?

• Colloids have small particles that are not visible by just looking. An example would be coffee.

• However, they show the Tyndall Effect (see the laser light line).

• They can not be separated by filtering.

o Suspensions have larger particles, often visible in size.

o The particles can be filtered out.

o It scatters light – No Tyndall Effect.

o If left undisturbed, the particles will settle to the bottom.

Solutions: 2 parts

–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!

The three methods to increase the rate of solution

for a solid are?•Heat it! •Crush it! •Stir it!

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

A decreasing air pressure

B stirring the waterC increasing the

temperature of the water

D using larger crystals of the solid

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 pressureB stirring the waterC increasing the

temperature of the water

D using larger crystals of the solid

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.

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 stirringH Lowering the air

pressureJ 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

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.

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

A 27°CB 48°CC 65°CD 80°C

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%

Concentrated or Dilute?

• A concentrated solution has as little solvent as possible.

• A dilute solution has added solvent.

• After adding more solvent, there is still the same mass of solute that you started with.

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

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

Higher pH levels means?33 Two clear solutions are placed in separatebeakers. The first solution has a pH of 4, and

the pH of the second solution is unknown. Ifthe two solutions are mixed and the resultingpH is 5, the second solution must have — A fewer suspended solidsB a lower temperatureC more dissolved salt (NaCl) particlesD 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.

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?

Now its your turn!

• Answer on your own paper the questions from the handout. We will check your answers before you leave.

Class TAKS Review Objective 4

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