Exam Review, Fall 2013.pptx

(1)

Exam Review,

Fall 2013

(2)

Significant Figures

Use with Measurements!

1. Leading 0’s NEVER count

2. Trailing 0’s count ONLY if

there is a decimal

3. Trapped 0’s ALWAYS count



_{Do not use SFs with FACTS}

or Counts!

Very important!

Use the measurements

in the ORIGINAL problem to figure out

how many SF’s you need.

(3)

Scientific Notation

• _{With Scientific Notation, you always have one, and only}

one, digit to the left of the decimal place

• _{When written in scientific notation, numbers}

greater than 10 have positive exponents

• _{Numbers between 1 and 10 are not written in}

scientific notation

• _{When written in scientific notation, numbers less}

(4)

Scientific Notation continued..

Multiplication

To multiply numbers written in SN, multiply the

coefficients and add the exponents

Division

To divide, divide the coefficients, and subtract the

exponent in the denominator from the exponent on the

numerator

Addition and Subtraction

Before you can add or subtract SNs, you must make the

exponents the same. It does not matter which exponent

you change.

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Lab Safety

(6)

• _{Confirming Test?}

–

_{Proves that a substance is}

present

• _{Qualitative Test?}

–

_{Identifies if something is, or}

is not, present

• _{Quantitative Test?}

–

_{Identifies how much of}

(7)

Evidence of a Chemical Reaction

o

_{Color Change}

o

_Temperature

Change

o

_{Gas Release}

o

_{Disintegration, or}

formation of a new

substance

o

_Precipitate

o

_{Odor Change}

(8)

ATOMS!

Atoms: building blocks of matter (smallest

particle possessing the properties of an

element)

Elements are composed of only one type

of atom

(9)

• _{Matter: anything}

that occupies space

and has mass

• _{Density: Mass}

(10)

• _{Compound—2 or more elements}

combined in fixed proportions

• _{Molecule—the smallest particle of a}

substance retaining all properties of

the substance

(11)

Periodic Table

Know the names =

symbols of the 1

st

36 elements!

Plus other common

ones: Hg, Au, Ag, Pb,

Xe, Rn, Sn, etc.

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Atomic Number vs.

Mass Number vs. Atomic Mass

Atomic Number

•Always the number of protons the element has

•Uniquely identifies the element

•Always a whole number

Mass Number

• _{Number of Protons and Neutrons (found in nucleus)…}

always a whole number

Atomic Mass

(AMU for a single atom or

compound---grams for a mole)

• _{Mass of protons, electrons, and neutrons}

• _{Not a whole number…why?}

(13)

Isotopes are

different types of

atoms of the same

element that have a

different number of

neutrons

Identify it this way:

(14)

Chemical Equation

Reactants Products

(15)

Electrical Nature of Matter

• _{Protons +}

• _Electrons

(16)

• _{Physical Properties: color, luster,}

boiling/melting/freezing point, density, odor

–

_{Properties that can be determined without}

changing the chemistry of the material

• _{Physical Change: Material remains the same}

although the form seems to have changed

(copper coin/copper wire)

(17)

• _{Chemical Properties:}

Reactivity, pH, types of

bonds that will form,

oxidation states,

combustibility,

• _{Chemical Change:}

–

_{Formation of gas or solid,}

permanent color change,

temperature change,

(18)

Ions and Ionic Compounds

Atoms gain/lose electrons to become ions

• _{Electrically charged atoms or groups of atoms}

–

_Cation?

–

_Anion?

Polyatomic Ions: NO

3-

, HCO

3-

, PO

4

3-Sodium Ion: 11 protons (11 + charge)

+ 10 electrons (10 – charge)

(19)

(20)

A compound must be

electrically neutral!

If you have Na

+

+ SO

4 2-

, you would

have NaSO

₄

-To make it electrically neutral, you

must have 2 sodiums! Na

2 SO

4

(21)

Periodic Table

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Organizes metals, non-metals

and metalloids

• _{Are there more metals or non-metals?}

• _{Properties of metals?}

• _{Properties of non-metals?}

(23)

Organization of the Table

• _{Groups/Families}

• _Periods

• _{Atomic Number}

• _{Atomic Weight}

• _{Oxidation number}

(Ionic Charge)

• _{Valence electrons}

(24)

SI Numbers!

Quantity Unit Abbreviation Mass kilogram kg

Length meter m Time second s Temperature kelvin K Amount of Substance mole mol Electrical Current ampere A Luminous Intensity candela cd

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Metric Prefixes

Prefix Abbreviation Meaning Example

mega- M 106 _{1 megabyte = 1,000,000 bytes}

kilo- k 103 _{1 kilogram = 1,000 g}

deci- d 10-1 _{1 deciliter = 0.1 liter}

centi- c 10-2 _{1 centimeter = 0.01 meter}

milli- m 10-3 _{1 milliampere = 0.001 A}

micro- u 10-6 _{1 micrometer = 10}-6_m

nano- n 10-9 _{1 nanometer = 10}-9_m

(26)

Know numerical prefixes

1 = mono-

6 =

hexa-2 = di-

7 =

hepta-3= tri-

8 =

octo-4 = tetra-

9 =

nona-5 = penta-

10 =

(27)

deca-Activity Series

Some Metals

are more

reactive than

others

(28)

LEO the lion says GER!

L

osing

E

lectrons =

O

xidation

G

aining

E

lectrons =

(29)

Redox Reactions!

Electron Transfer:

Reduction—Gaining electrons

Oxidation—Losing electrons

They occur simultaneously!!

Cu(NO

3

)

2(l)

+ Mg

(s)

→ Mg(NO

3

)

2 (l)

+ Cu

(s)

What is reduced? What is oxidized? Spectator ion?

Reducing Agent? Oxidizing agent?

(30)

Electroplating

• _{Redox Reaction!}

• _{Requires a Power Source}

• _{Anode (+) provides}

electrons and metal that

provides plating material

• _{Cathode (-) receives}

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Three key points!

1) Reduction is a gain of electrons, Oxidation is

a loss of electrons

2) The reactant that produces electrons is the

reducing agent – it gets oxidized.

3) There can be no oxidation without reduction

and vice versa !

(32)

Cu(NO

3

)

2 (aq)

+ Mg

(s)

→

Mg(NO

3

)

2 (aq)

+ Cu

(s)

The less reactive metal wants to be

on its own as a free metal (solid)

….the more reactive metal forms

dissolved ions and goes into

(33)

To reduce metal ions

and get free metal out of ores:

• _{Pyrometallurgy}

• _{Hydrometallurgy}

(34)

The same quantity can be expressed in many ways.

1 dollar =

4 quarters =

10 dimes =

20 nickels =

100 pennies

Different ways to express the same amount

Dimensional Analysis:

(35)

Whenever two

measurements are equal, a

ratio of these two

measurements will equal 1

100 cm = 1 m = 1

1 m

100 cm

(36)

Which one?

1 kg or 1,000 g

1,000 g 1 kg

Choose the one that allows you to cancel

the units!

2,678 g x 1 kg = 2.678 kg

1,000 g

(37)

Percent Composition

Grams of element x 100 % = % composition of

Grams of compound element

An 8.2 gram piece of Ca combines completely

with 5.4 g of Oxygen to form a compound

(CaO). What is the % composition?

% Composition refers to

all

the components of

the molecule!

(38)

Conserving Matter

• _{Law of}

Conservation

of

Matter---matter is

neither

created nor

destroyed

(39)

Atom Inventories/Balancing Equations

• _{Since matter is neither created nor}

destroyed, atoms can always be

accounted for

2H

2 + O

2 → 2 H

2 O

The atoms on the reactant side must be

the same as the atoms on the product

side

(40)

Balancing Equations:

Coefficients are used to balance

equations—they reflect the

relative number of units of

each substance involved in

the reaction

Subscripts indicate the number

of atoms present in a

(41)

Rules for Balancing Equations

Determine the correct formulas for all reactants

and products

Put the reactants on the left side of the yields

sign (→) put the products on the right

(42)

C

2 H

5 OH + O

2 → CO

2 + H

2 O

1) Set the equation up algebraically:

(43)

2) Do an atom inventory:

a

C

₂

H

₅

OH +

b

O

₂

→

c

CO

₂

+

d

H

₂

O

C: 2

a

=

c

H: 6

a

= 2

d

(44)

3) Make one coefficient = 1; solve for

the other coefficients:

a

= 1

C: 2(

a

) =

c

, 2(1) =

c

,

2 =

c

H: 6(

a

) = 2(

d

), 6(1) = 2

d

, 6 = 2

d

,

3 = d

O:

1 a

+ 2

b

= 2

c

+ 1

d

, 1(1) + 2

b

= 2(2) + 1(3)

Solve for b: 1 + 2

b

= 7, 2

b

= 6,

b = 3

a

C

2 H

5 OH +

b

O

2 →

c

CO

2 +

d

H

2 O

(45)

Zn:

a

(1) =

c

(1) →

a

=

c

H:

b

(1) =

d

(2) →

b

= 2

d

Cl:

b

(1) =

c

(2) →

b

= 2

c

3) Make one coefficient = 1; solve for the other

coefficients

a = 1

. Since a = c,

c = 1

.

b = 2c --- b = 2 (1) ---

b = 2

(46)

4) Do another atom inventory

C

2 H

5 OH +

3 O

2 →

2 CO

2 +

3 H

2 O

C: 2 → 2

H: 6 → 6

0: 7 → 7

(47)

Molecules,

Compounds

• _{Molecule: electrically neutral -- group of atoms}

(can be same element) that act as a unit

Compound: Molecule with at least 2 different

elements

• _{Molecular/Covalent compound: electrically}

neutral-- composed of 2 or more atoms,

non-metals

• _{Ionic Compound: electrically neutral—}

_usually

(48)

Ionic Bonding

• _{Occurs between a metal and a non-metal}

• _{The result of anions and cations being}

attracted to one another—will form an

electrically neutral compound

(49)

Valence Electrons?

Involved in bonding!

(50)

Naming Rules

• _{Cation is named first then anion}

• _{Cation retains its name}

• _{Anion ends in “-ide”}

–

_{unless it is a polyatomic ion}

(51)

Covalent/Molecular Bonding:

Non-metal to a non-metal

(52)

Naming Rules for Covalent/Molecular

Compounds

• _{Name of 1}

st

non-metal

remains the same.

• _{Name of 2}

nd

non-metal

ends in “-ide”

• _{Use prefixes when there}

are multiple atoms

• _{Use “mono” only for the}

2

nd

non-metal, not for the

(53)

Some Ionic Compounds…..

Many Transition Metals can give up

different numbers of electrons:

Pb, Hg, Fe, Cu, Sn. (Exceptions to this

include Al

+

_{and Zn}

2+

₎

An example is Iron, which can form

FeCl

₂

and FeCl

₃

…Are both Iron chloride?

We need a way to distinguish between

them….

look to the anion

Use Roman Numerals! Use Roman numerals

ONLY when you are writing out the name of

the compound…not when you are using the

symbols!

(54)

Octet Rule!

All atoms want to get to the most

stable state or electron

configuration possible

Noble Gases are already in a very

high state of stability: He, Ne, Ar,

Kr, Xe, Rn.

Why are they so stable?

Full Valence shell

Exceptions: H, He, Li, Be (stable with 2

valence electrons)

(55)

The Mole!

A Counting Unit: 6.022 x 10

23

(56)

Molar Mass

The mass of one mole of

a substance (atoms or

molecules) in grams

What is the mass of

6.022 x 10

23

molecules

of

3 Zn(NO

3

)

2

?

What is the mass of one

molecule of

(57)

Mass

• _{Mass of one atom of}

potassium is 39.10 amu

• _{Mass of one mole of}

potassium is 39.10

grams

• _{Mass of one molecule}

of H

2 O is 18.01 amu

(58)

Moles in a Reaction

Cu + 2Ag(NO

₃

) → Cu(NO

₃

)

₂

+ 2Ag



_{Coefficient represents the}

number of moles

(59)

(60)

(61)

Note: All Gas

Laws refer to

KELVIN…

You must convert

temperature to

(62)

Kinetic Molecular Theory (KMT)

1) Gases consist of tiny particles of

negligible volume that are far apart

2) Gas molecules are in constant,

random motion – kinetic energy—

elastic

collisions (no energy is

gained or lost)

3) Particles move in straight lines and

do not interact with other particles

4) Kinetic Energy is directly

(63)

Ideal Gas vs. Non-Ideal Gases

Ideal Gas Real Gas (Non Ideal) Made of particles that have mass Same

Mostly empty space same In constant, random motion same NO attractive or repulsive forces

between particles Some attractive or repulsive forces between particles Particles have NO volume Particles have some volume