1st Chem finals units 1-3

Qualitative

Description/ story’s

Quantitative

Numbers / data

Leading zeros (sig fig rule)

No significant

Ex: 0.0025 —> 2 sf

Linear

2 bonding sites, 0 lone pairs, nonpolar, 2d

Trigonal planar

3, boding sites, 0 lone pairs, non polar, 2D

Tetrahedral

4 bonding sites, lone pairs, nonpolar, 3D

Trigonal pyramidal

3 bonding sites, 1 lone pairs, polar, 3D, asymetrical

Bent

2 bonding sites, 2 lone pairs, polar 3D

Symmetrical

They cancel each other, nonpolar

Asymmetrical

They compound each other, polar

Intermolecular attraction

Strength of attractive force that holds it particles together

• gas< liquid< crystalline solid

INTRAmolecular attractions

Found within te molecule (covalent, ionic,) stronger

Intermolecular attractions (IMA’s)

Attractive forces between separate molecules

• holds the molecules close to other molecules, (weaker)

Substances with …… IMA’s will be gases at room temp

Weak

Substances with…..Ima will be liquid at room temp

Middle

Substances with … IMA’s will be solids at room temp

Strong

Dipole- Dipole attractions

Polar, no H-F, H-O, or H-N

Hydrogen bonding

H is boned to either N,O or F, polar, strongest

Dispersion forces (London dispersion forces)

Only Nonpolar molecules and unbounded atoms, temporary dipoles, weakest

The strength of dispersion forces depend on ……

• The # of electrons: more electrons = stronger dispersion forces

• the number of atoms in a molecule

Network covalent

• very hard, very high melting points, most are nonconductors

• Diamon and graphite (both carbon), silicon & silicon dioxide, any combinations of C, SI, W, B

Metallic

When a metal sits by its self

More electrons = …. Boiling point

Higher

Weak IMA’s means evaporation happens…..

Quickly, higher vapor pressure

Strong IMA’s means evaporation happens…..

Slowly, lower vapor pressure

Vapor pressure

A measure of pressure exerted by vapor on liquid below

Larger surface area = …. Evap

Faster

Increase in temp= …. Evaporation

Quicker

The longer the length of a molecule chain leads to …..interactions and a …..boiling point

Stronger interactions and a higher boiling point

Ionic bond

Metal and nonmetal

Substance melts about 100º C, dissolves in water, and conducts in water, its a …… type of solid

Ionic

substance melts about 100ºC, and conducts as a solid, its a ..... type of solid

Metalllic

substance melts in building water, does not conduct when dissolved in water and is soft, its a ...... type of solid

Covalent

substance melts above 100º C, does not dissolve, does not conduct, and is hard, its a ....... Type of solid

Network covalent

The..., the T value = the... the intermolecular force (IMA)

Smaller… stronger

The.....the bond the ...... the bond length

the more the bonds the shorter the bond length is

Atoms are more stable when they are …..

Bonded

Types of bonds are … (4)

Ionic bonds (+ and - ions), Covalent bonds (sharing), Nonpolar covalent bonds, Polar covalent bonds

Electronegativity is the ability of…

An atom to attract electrons in a bond

En (electro negativity) increase from

L→R, and Top to bottom

An En difference of .7 or greater (bond)

Ionic bonds

An En difference of 0 (bond)

Nonpolar covalent

An En difference between 0 and 1.7 (bond)

Polar covalent bonds

Ionic bonding in metals

Like to lose electrons, low ionization energy, produce positive ions

Ionization energy

The amount of energy required to remove an electron from an atom

Exceptions to the octet rule

Hydrogen [H], Helium [He], lithium [Li]: 2 valence e

Beryllium [Be]: stable with 4 ve

Boron [B]: stable with 6 ve

Covalent bonding

When 2 nonmetals bond they must share electrons

Polar covalent bonds

Electrons are shared unequally between atoms

• huge En difference

• Partial charge

• 0<En<1.7

Nonpolar covalent bonds

Electrons are shared equally

• no charge

• En= 0

Oxoacids

They hydrogen is attached to an oxygen which is attached to the central acid (non metals

Bond strength (least to greatest)

Single bond < double bond< triple bond

Valence shell electron Pair repulsion theory (Vsepr)

You can predict the shape of a molecule depending on repulsion of electron pairs in the valence shell of the central atom

• electrons repel each other

Steric groups are…

Single bond, triple bonds double bond, lone electron pairs

Which would repel other bonds more within a molecule, Why

lone electron pairs (lone pair): it’d closer to the central atoms nucleus so it has greater repulsion

Diatomic molecules (7)

Br, I, N, CL, H, O, F

Intermolecular molecular bonds

Dispersion, Dipole-Dipole, hydrogen bonding

INTRAmolecular bonds

Ions (+,-), metallic(+), network covalent

Element

substance that cannot be separated into simpler substances by a chemical change

Compounds

Formed of 2 or more element chemically bonded

• cannot separate by physical means

Mixtures

A physical combination of 2 or more substances

Alloys

Homogeneous mixture of metals

Steel, brass, bronze, Nichrome, solder

Chemistry

Study of matter and how it changes

Zeros in between (sig fig rule)

Are significant

Ex: 1.0025 —> 5 sf

Trailing Zeros (sig fig rule)

Significant if there’s decimals

Ex: 100–> 1 sf or 1.00 —> 3 sf

Rounding sig fig.

Round 19,876 to 3 sf

1.99×10^4

Rounding sig fig.

Round 19876 to 2 sf

2.0×10^4

Multiplication/division (sig figs)

Same # sig figs as lowest #

Ex: 9.325 × 1.2 =11.19 = 11

• rounds to 2 sig figs

Addition / subtraction

Same # decimal places smallest decimal place

12.15+ 1.1+3.125 =16.375 = 16.4

• rounds to 1 decimal place

Rounding on a calculator (sig figs)

Only round at the end or when hanging operation types

Ex: addition/ subtraction —> multiplying/dividing

Scientific Notation rule

Express # between 1 and 10

Ex: 1230 = 1.2×10³ Or 0.024 = 2.4×10^-2

• positive exponents = big numbers

• Negative exponents = small numbers

Physical change

Different physical form but sill same substance

• phase changes, bending, tearing, dissolving sugar in water

Chemical change

You get something new

• burning, color change, cooking, rusting baking, rotting

Density, Mass, Volume equations

D=m/v, M= DxV, V=M/D

Percent Error Equation

(Experimental - theoretical)/ theoretical x100

• experiment = data from lab

• Theoretical = correct/ accepted value

Heterogeneous

Visible appearance

• M&M cookies, salad, pizza

Homogeneous

Uniform appearance

• air, sea water, kool Aid

Protons

Mass: 1 amu

Charge: +1

Location: Nucleus

Role: identity of the atom

Neutrons

Mass: 1 amu

Charge:0

Location: Nucleus

Role: “glue” inside nucleus

Electrons

Mass: 0.005 amu

Charge: -1

Location:outside nucleus

Role: responsible for charge

Atomic Number

The number of protons in the nucleus

Mass Number

The sum of protons + neutrons

Neutral atoms

Contain equal # of protons and electrons

Isotope

Same element different numbers of neutrons

Ions

Atoms which have unequal numbers of protons and electrons

Anion

Gain electrons = negative

Cation

Loses electron = positive

Avg atomic mass equation

(Exact mass x decimal abundance) + (m x a) ….

Avg weighted cost equation

(#/ total of all combined items) (Avg. cost) +….

Orbitals

As energy level increase, the number of different shapes and types of spaces increase (the spaces are orbitals)

• each orbital holds only 1 pair of electrons

S sub shell

2 electrons , 1 orbital

P sub shell

6 electrons, 3 orbitals

D sub shell

10 electrons, 5 orbitals

F sub shell

14 electrons, 7 orbitals

Aufbau Principle

Electrons always fill low energy level to high

1s,2s,2p,3s,3p,4s,3d,4p….

Hunds rule

The lowest energy config. Fro an atom is the one having the max # of unpaired electrons

Smallest to largest of : energy level, atom, sublevel, and orbital

Smallest —————> largest

Orbital → sublevel →energy level → atom

Pauli Exclusion principle

Each orbital can hold a max of 2 electrons as long as they have opposite “spin”

Paramagnetic

Atoms have unpaired electrons affected by a magnet

• the more electrons = the more it is affected by a magnet

Diamagnetic

Have only paired electrons, not affected by magnets

Short hand configurations / orbital configurations

[Nobel gas], rest of subshell config