General Chemistry 131 Final Exam

Matter

Anything that occupies space, tangible, anything with mass

Mass

The amount of matter in an object

Physical Quantities

Mass=kilograms (kg)

Length=meter (m)

Time=seconds (s)

Amount=moles (mol)

Temperature=kelvin (K)

Kilo

k

1 kg=10³ grams

Centi

c

1 cg=10⁻² grams

Milli

m

1 mg= 10⁻³ grams

Micro

(weird u shape)

1 microgram= 10⁻⁶ grams

Nano

n

1 ng= 10⁻⁹ grams

Precision

How close together measurements are

Accuracy

How close a set of measurements are to the true value

Significant Figures (SigFigs)

The number of meaningful certain digits and one uncertain digir

Rules for Sig Figs

1) Zeros in the middle of the number, like any other digit, are significant

2) Zeros at the beginning of a number are not significant, they simply tell where the decimal point is.

3) Zeros at the end after the decimal are always significant; zeros wouldn't show unless they were significant

4) Zeros at the end may or may not be significant, they might be apart of the measurement or locate the decimal

5) Certain numbers are exact

To report correct sig figs on digital read-

All digits are significant and should be reported, ALWAYS report from the bottom of the meniscus

To report correct sig figs on non-digital reads-

Report one digit past the lines on the measuring device, report at the bottom of the meniscus

Rules for Rounding

-If the first digit you remove is less than 5, round by dropping it and all following digits.

-If the first digit you remove is more than 5, round up by adding 1 to the last kept digit.

Keeping Sig Figs in Math Operations

Multiplication and Division

-The answer CANNOT have more sig figs than any of the original numbers

-The answer has to have the same number of sig figs as the number used with the least number of sig figs.

Addition and Subtraction

-After lining up the decimal points, the answer can't have more sig figs to the right than any of the original numbers

Performing Multiple Steps

-Keep track of the number of sig figs in each step

-Round at the end

Equation for Density

Mass (g)/Volume (mL or cm³)

Celsius to Farenheit

(9°F/5°C) x °C +32°F

Fahrenheit to Celsius

(5°C/9°F) x (°F-32°F)

Temperature in Kelvin

°C+273.15°

Temperature from Kelvin to Celsius

K-273.15°

Energy

The ability to do work or the ability to supply heat

Total Energy (E)

Kinetic energy+Potential energy

E(k)=kinetic, energy of motion

E(p)=potential, potential to supply energy (stored energy)

Kinetic Energy E(k)=

(1/2)mv²

m=mass (kg)

v=volume (d/t), (m/s)

(1/2) kg x (m/s)²

Energy Conversions

1 cal=4.184 J

1 Cal=1000 cal

1 Cal= 1 kc

1 J=1000 kJ

The periodic table is organized by...?

Number of protons, ATOMIC NUMBER

Periods on the Periodic Table

Rows, properties of elements change a lot moving across the rows

Groups on the Periodic Table

Also called families, columns, properties are similar within a column (top to bottom)

Chemical VS. Physical Properties

Chemical:

-Describes a substance reacting (or not) to form other substances

-Iron rusting, something burning, tarnishing metal

Physical:

-Does not involve a change in identity of a substance

-Color, Ice melting

-Boiling and melting point, paper tearing, malleability, size, conductivity

Extensive VS. Intensive Properties

Extensive:

-Depends on SIZE, however, density is NOT extensive

Intensive:

-Doesn't depend on SIZE

-Color, metal rusting, burning wood, DENSITY, wood floating on water

Properties of Group 1

Alkali Metals

-Soft, silvery metals

-NEVER found in elemental forms in nature

-Make salts

-Elemental forms react rapidly and violently w water

-More reactive toward bottom of column

Properties of Group 2

Alkaline Earth Metals

-Silvery metals

-NEVER found in elemental forms in nature

-Make salts

-Less reactive than Alkali metals

-Make basic solutions in water

-More reactive towards bottom of column

Properties of Group 7

Halogens

-NEVER found in elemental forms in nature

-Make salts

-Colorful, corrosive non-metals, except for astatine (semimetal)

Properties of Group 8

Noble Gases

-Typically found in nature

-Very inactive

-Colorless gases

Element

A fundamental substance that can't be broken down into anything simpler

Main Groups

Two larger groups on the left and the six larger groups on the right (Groups 1,2,13,14,15,16,17,18)

Transitional Metal Groups

10 smaller middle groups (3-12)

Inner-transition Metal Groups

14 groups below the main periodic table

Characteristics of Metals

Solid at room temp (except Mercury), most have a silvery shine, malleable NOT brittle, good conductors of heat and electrivity

Characteristics of non-metals

None are silvery, some are colorful, brittle, do not conduct heat or electricity

Characteristics of Semimetals

Most are silvery in appearance, solid at room temperature, brittle, poor conductors of heat and electricity

Chemical Compounds

Atoms joining together in different ways to create a vast number of substances

Chemical Formula

lists the symbols of the constituent elements and uses subscripts to indicate the number of atoms in each

Chemical Equation

in which the reactant substances undergoing change are written on the left, products on the right, and arrows show the direction of the reaction

Law of Mass Conservation

Mass is neither created nor destroyed in a chemical reaction

Law of Definite Proportions

Different samples of pure chemical compound always contain the same proportion of the elements by mass

Law of multiple proportions

Elements can combine in different ways to form different chemical compounds, whose mass ratios are simple whole numbers that are multiples of each other

Elements are categorized by...?

the mass of its atoms

Alpha particles

type of emission given off by a number of naturally occurring elements, 7000 times more massive than an electron. Charge=2e⁻

Nucleus

Mass concentrated in a central core of the cell

Protons

Positive charge (# of protons and electrons in an atom are equal)

Neutrons

No charge

Atomic Number

number of protons in an atoms nuclei, # of electrons

Mass number

the sum of the protons and the neutrons in the nuclei

Unified Mass Unit

u

Atomic mass unit, (amu)

Atomic Mass

Mass of a specific atom

Atomic Weight

Weighted average of the atomic masses of the elements naturally occurring isoptopes

Mole

One mole of any element is the amount whose mass in grams called MOLAR MASS is equal to atomic weight

Equation for Average Atomic Mass

∑(Mass of isotope(%/100%))

Principal Quantum Number

n

Ranges from one to infinity in integer values. As n increases, the radius of the orbital increases

n↑, size↑

Angular momentum

L

Ranges from 0 to n-1

Integer values and whole numbers

Defines the shape

each value has a letter abbreviation

Equation for Change in Energy

∆E=E(final)-E(initial)

Positive change in energy means...?

Energy is required/put in for the reaction to take place, occurs when n is increasing

Negative Change ion energy means...?

Energy is released, let out, when n is decreasing

Ground state

e⁻ in the lowest energy orbital, MOST STABLE STATE OF THE ATOM

Excited State

e⁻ not in the lowest orbital, not stable

Wavelength

λ

The distance or length of one repeating unit of a wave (meters)

Frequency

v

# of repeating units that pass a point in a specified amount of time

Equations to find Light

v=c/λ

E=hv=hc/λ

Orbitals

indicate where the e⁻ is likely to be

-each orbital corresponds to a particular energy

-waves of electrons

Angular Momentum (L)= 0

s orbital

sphere shape

Angular Momentum (L)=1

p orbital

dumbell shape

Angular Momentum (L)=2

d orbital

double dumbbell shape

Angular Momentum (L)=3

f orbital

undefined shape

Magnetic Quantum Number M(l)

ranges from -l to l passing through 0

each value corresponds to an orbital w a different orientation in space

If n=1...?

l=0

M(l)=0

Orbital=1s

Number of orbitals in shell=1

If n=2...?

l=0, 1

M(l)= -1,0,1

Orbital=2s or 2p

If n=3...?

l=0,1,2

M(l)=-2,-1,0,1,2

Orbital=3s,3p,3d

If n=4...?

l=0,1,2,3

M(l)=-3,-2,-1,0,1,2,3

Orbitals=4s,4p,4d,4f

Spin Quantum Number

M(s)

+1/2 or -1/2

Effective Nuclear Charge

Zeff

Charge from the nucleus that the e⁻ actually "feels"

=Zact-S

Zact=# of protons

S=Shielding (repulsions from other e⁻)

Zeff↑,size↓

Afbau Principle

-Lower energy orbitals fill first, before higher energy orbitals

-an orbital cal only hold 2 electrons and they must have opposites spins

-If two or more degenerate orbitals are available, one e⁻ goes to each until each are half full

S block

Li and Be down, n being filled matches period #

P block

B→He/Ne down

n being filled matches period #

D block

Sc→Zn and down

n=period #-1

F block

La→Yb and down

n= period #-2

Relationships between energy, period, and size

Zeff↑ moving left to right across the table

F: High for EN, Eea, Ei, Zeff

Low for size/radius,volume

Top to bottom: n↑, ↑radius, size

Left to right: ↑Zeff, ↓Radius, size

Ionization Energy

E(i)

Energy required to remove an electron from an atom

Requires energy

Left to right: Zeff↑, E↑

Electron Affinity

E(ea)

Energy involved in adding an electron to an atom

Larger Tea is more negative, more favorable to gain an electron

Negative ion

anion

gains e⁻

Positive ion

cation

loses e⁻

The Octet Rule

Main groups tend to undergo reactions that leave them with a total of 8 or 0 electrons in their valance s and p orbitals

The Octet Rule regarding H and He

These will undergo reactions that leave them with 2 or 0 valence s orbitals

When losing electrons...

p block- loses p e⁻s then s e⁻s

s block- loses s e⁻s

d block- lose s e⁻s then de⁻s

f block- loses s e⁻s then f e⁻s

Covalent Bonds

No metals or NH₄⁺

Involve sharing of electrons

Between two nonmetals, two semimetals, or one of each

Polar Covalent Bond

Two different elements (NOT C-H bonds)

Non-Polar Covalent Bonds

Two of the same elements bonded together AND C-H bonds

Elements that form Covalent bonds

-Nonmetals and semimetals

-Metals usually don't form covalent bonds

-Compounds held together just by covalent bonds with no charge are called molecules

Molecular Elements

-Elements found as molecules with covalent bonds between atoms

-Found in upper right hand corner

-H₂,N₂,O₂,F₂,Cl₂Br₂,I₂

Ionic Bonds

Occurs between metal or NH₄⁺ and something

Held together by oppositely charged ions

Have a lattice structure