Class TAKS Review Objective 4

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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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The 3 types can be further separated in two
categories

• Mixtures are not pure substances and we will deal
  with them in a few minutes.

• Pure Substances
• Elements are the simplest pure substances

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

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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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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 NO31-.
• 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?
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.
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Na
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.
22.990 sodium
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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3 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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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

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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
• CO2

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Special Names of Compounds Acids and Bases

• 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

• Bases end in the hydroxide anion OH-
• They are named with the metal and hydroxide.
• NaOH is sodium hydroxide

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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 tablet B The severity of the
patients cold symptoms C The chemical formula
for vitamin C D The amount of time before
symptoms improve
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What doesnt 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 differences
• C 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.
  

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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 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.

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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.

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Density Mass / Volume THIS IS FROM THE FORMULA
PAGE

• 25 A block of maple wood with a volume of
• 405 cubic centimeters and a density of
• 0.67 g/cm3 is sawed in half. The density
• of the two smaller blocks is now
• A one-fourth the original density
• B one-half the original density
• C two times the original density
• D 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!
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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.

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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?
Since 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.

• A 40 g B 88 g C 104 g D 256 g

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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
2
H OH
2
2

• 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.
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Balance the equation below, the boxes should get
the coefficients.
2
2
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?
C
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The 3 types can be further separated in two
categories

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

• Pure Substances
• Elements are the simplest pure substances

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

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Decide if the substance is Element, Compound ,
or Mixture?
1. Water
1. Compound
2. Compound
2. Table Salt
3. Element
3. Oxygen
4. Mixture
4. Dirt
5. Mixture/Solution
5. Air
Click Mouse button to see answers!
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Lets try a few more!
6. Copper
6. Element
7. Solution/Mixture
7. Soda
8. Solution/Mixture
8. Steel
9. Mixture
9. Rain
10. Mixture
10. Ice-cream
Click Mouse button to see answers!
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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- mixture is not the same from place
  to place.
• Chocolate chip cookie, gravel, soil.

• Homogeneous- same composition throughout.
• 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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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.

• Suspensions have larger particles, often visible
  in size.
• The particles can be filtered out.
• It scatters light No Tyndall Effect.
• If left undisturbed, the particles will settle
  to the bottom.

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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!

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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?

• What are the 3 ways to increase the rate at which
  a solid dissolves?
• Heat it!
• Crush it!
• Stir it!
• ANSWER?
• J

• F Decreasing the water temperature
• G Stopping the stirring
• H Lowering the air pressure
• J Crushing the crystal

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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.

Grams solute/100 g H2O
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• 51 At which temperature do KBr and KNO3 have the
  same solubility?
• A 27C
• B 48C
• C 65C
• D 80C

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Try this one!
49 According to the graph, about how
much hemoglobin would be saturated at an
O2 pressure of 7.3 kPa? A 32 B 67 C 89 D 92
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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.

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

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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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Now its your turn!

• See if you can complete the questions provided.
  Be sure to ask a science teacher before next
  Friday, if there is a question you do not know.