UC Berkeley Chem 1A Midterm 1 Fall 2023 Flashcards

What is Chemistry?

The study of matter and the changes it undergoes

Amino Acids

Found in food, tastes somewhat bitter.

Pattern: C with C, C, N, H bond

Neurotransmitters

Found in the body, tastes bitter

Pattern: 6 C bond with double bonds in every other C, has a tail

Metal Chlorides

Found in the ocean, tastes salty

Pattern: molecule is switched every other

Isomers

Same molecular formula, different structural / atomic formula

Bonding ratio increases from

left to right (then center 1:4 , switched)

Reactivity increases from

Metals: top to bottom (due to increased radius, has less force, so easier to react!)

Non-metals: bottom to top

Mass increases from

top to bottom ⬇️ and left to right -->

Radius increases from

top to bottom⬇️ and right to left <--

Can make weaker attraction if ^ bigger radius

- reacts easier?

- cuts easier?

Hardness increases from

bottom to top (metals)

Coulomb's Law

F = kq1q2/r^2

Same sign (++, --) = REPEL

Opposite Sign (+-) = ATTRACT

Bigger q = stronger force

Bigger distance = weaker force

Z

Atomic # --> also # of protons (and electrons if neutral)

Average atomic mass

# of protons + average # of neutrons (atomic mass - atomic # or Z )

In Real Gas Law, what does the B stand for?

B = bigness coefficient. Depends on the radius / volume in PV = nRT

In Real Gas Law, what does the a stand for?

a = attraction coefficient

What is Zeff & how to find Zeff?

Zeff is the effective nuclear charge

# protons (Z) - # core electrons

Cation vs Anion behaviors

Cations (+) are positive charged ions that lost 1 or more e-

Anions (-) are negative charged ions that gained 1 or more e-

In electronegativity, is # of shells or # of protons more important? Why?

# of shells

This is due to radius. If the molecule have a tighter radius = ^ more force

How to find molecular geometry / electron domain ?

1. Count # of electron domains around central atom

- determines if linear, trigonal planar, or tetrahedral

2. Count # of lone pairs

Metallic Bonding

Exists in substances consisting of only metallic elements

valence e- are free to move throughout the "electron sea"

- conducts

- 🚫 dissolve

- bendable / maleable

Extended / Network Covalent

Exists in substances consisting only of NONmetal elements

valence e- connect atoms w/ each other in 1, 2, or all 3 directions to create chains / networks

- 🚫 conduct

- 🚫 dissolve

- rigid / hard to break

Molecular Covalent

Exists in substances consisting only of NONmetal elements

valence e- are shared between some atoms, creating small stable units

- 🚫 conduct

- most dissolve

- gases, liquids, or soft solids

Ionic Bonding

Exists in substances consisting of metal AND nonmetal elements

metal atoms "give up" their ve- --> nonmetal atoms

- 🚫 conduct

- most dissolve

- hard, but brittle

When charges get too close, atoms fly apart !!! so can break/ snap/ crack

Noble Gas Envy

Atoms gain + and lose - electrons to fulfill their Noble Gas Envy!

Want to make an octet or 2 ve-!

3 and below --> rows of periodic table = can have more than 8 ve-

Metals tend to___ while nonmetals tend to ____

Metals tend to LOSE - ELECTRONS while nonmetals tend to GAIN + OR SHARE ELECTRONS.

How to draw lewis structure?

1. Count total # ve-

2. Arrange non-H atoms w/ 1 bond between each

3. Add H's to ends (HONC)

4. Add long pairs as needed to get octet

5. Re-count e- & make multiple bonds as needed

6. if have time, check FC!

How to check Formal Charge?

# valence electrons when alone - # of bonds - # non bonding e-

Resonance Contributors

Using multiple drawings to represent a structure -

same molecular formula, different electron placement

Kinetic Molecular Theory

1. Constant random motions --> straight lines

2. Elastic collisions between particles (no loss of energy)

3. Particles are infinitely small (no volume)

KE formula

KE = 1/2 * mv^2

m = mass

v = velocity (🚫 volume!)

KE = 1/2 mv^2 = 3/2 RT

High T = KE wins (gas)

Charles's Law

Volume + Temp proportional WHEN pressure held constant

V = kT

Gay-Lussac's

Pressure + Temp proportional WHEN Volume + Moles of gas held constant

P = kT

Bolye's Law

Volume + Pressure inversely proportional (^ P = ⬇️V)

Avogadro's Law

volume of gases = number of molecules WHEN Pressure + Temp stay constant

V

Volume

v

velocity

2 Types of container:

1. Flexible (variable V)

2. Rigid (fixed V)

V Bar

average / most popular velocity

K

kelvin --> Celcius + 273.15

n

Number of moles --> PV = nRT

r

Gas constant --> PV = nRT, typically 0.0821 L atm/molK

Pa, Torr, Bar

Pa = Pascal

Units of measure for pressure

Boiling Point

STRONGER attractions = HIGHER temp (more KE required)

Temp @ which its equilibrium vapor pressure = to pressure exerted on the liquid by its gaseous surroundings

i.e. if an open container, pressure = Earth's atmosphere

- presence of an Oxygen can raise boiling point by a lot

Real Gas Law

High T favors _______, Low T favors ______

High T favors motion of gases, Low T favors attraction of liquids

PE

Potential Energy - Attractions between atoms

Low T = PE wins (Liquid)

VSEPR Theory

Valence Shell Electron-Pair Repulsion Theory

Assumes the e- pairs --> valence shell of central adom will adopt an arrangement that MINIMIZES repulsions by MAXIMIZING distance

VSEPR Theory for 4 e- domains

109.5 degrees

e- geometry = tetrahedral

molecular geometry =

- if 1 lone pair: trigonal pyramidal

- if 2 lone pairs: bent

VSEPR Theory for 3 e- domains

120 degrees

e- geometry = trigonal planar

molecular geometry = bent

VSEPR Theory for 2 e- domains

Linear, 180 degrees

Polar Covalent Bond

unequal sharing of electrons

Non-polar Covalent Bond

equal sharing of electrons

Electronegativity increases from...

left to right -->, bottom to top^

Electronegativity

Ability of an atom to attract electrons to itself BASED ON Zeff!

- nonmetal vs nonmetal EN = similar (covalent bonds)

- metal vs nonmental EN = diff (ionic bonds)

Nonzero net molecular dipole

Will cause the molecule to be dipole-dipole, when the EN do not cancel out (x, y directions)

Dipole-Dipole interaction

an attraction between regions of PERMANENT POLAR molecules (x, y of EN doesn't cancel) that have partial charges of opposite sign

H-Bond counts as D-D when also interacting w/ lone pair

Induced Dipole - Induced Dipole interaction

ALL (even nonpolar) have ID-ID

Dipole - Induced Dipole

A weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species.

Ion-Ion interaction

interactive force between ions of opposite charge. Ions will often be indicated w/ a charge around the species, showing FC that do not cancel out

requires nonzero FORMAL CHARGE

DIFFERENT from Ionic bonding *that is between a metal and a nonmetal.*

ion-dipole = ion attracted to polar dipole

Order from weakest - strongest IMF moments

ID-ID < D-ID < D-D < H Bond (NOT BOND) < I-D < ion-ion

Hydrogen Bond

Unusually strong Dipole-Dipole moment, between Hydrogen atom + N, O, or F

Needs a Negative acceptor (delta - N, O, F) and H-Positive bond donor (delta + H attached to a N, O, F)

What causes higher boiling point?

stronger intermolecular forces

Net Molecular Dipole

When add up all the bond dipoles, what it adds up to (nonzero, zero net molecular dipole)

Strength in ID-ID interactions depends on ____

Surface Area. So, longer, straight chains = stronger interaction (^ more opportunities to induce dipoles)

like dissolves like rule

Dissolution occurs only if pure substances' interactions are similar --> strength

i.e. ID-ID does not dissolve into or with D-ID

Solvent

Component of a Solution @ a significantly ^ larger concentration

Solute

Component of a colution @ significantly ⬇️ lesser concentration

Saturated

Max amount of solute dissolved

Unsaturated

Even ^ more solute could be dissolved

Precipitate

Extra / over saturated --> extra solute sits @ bottom & doesn't fully dissolve

Solubility & Temperature

solubility increases ^ = temperature increases ^, in general

Non-polar bonds --> periodic table

1. When an atom is bonded to the same atom

2. C-H bond

Dipoles and Polarity differences occur with what type of bond?

Covalent bonds!

Covalent bonds describe the sharing of electrons between two atoms. Polarity describes how evenly this is shared. So a nonpolar bond means the electrons are being shared pretty evenly.