CHEM 1150: Final Exam Review

intensive properties

properties that don’t depend on the amount of matter present (i.e, temperature, melting/boiling point)

extensive properties

properties that are dependent on the amount of matter present (i.e., length, volume)

group 1

alkali metals

group 2

alkaline earth metals

group 3-12

transition metals

group 17

halogens

group 18

nobel gases

diatomic elements

H₂ , O₂, N₂ , F₂ , Cl₂ , Br₂ , I₂

empirical formula

the simplest formula for a compound, showing atoms of a molecule in the right proportion, but not the right amount

molecular formula

the actual formula of a compound, with the component atoms in the correct numbers

how to find the # of empirical formulas

structural isomers

molecules with the same molecular formula but have atoms bonded in different orders

spatial isomers

molecules with the same molecular formula and atoms connected to other atoms by the same types of bonds but arranged differently

cisisomer

functional groups are on the same side of the molecule

transisomer

functional groups are on opposite sides of the molecule

enantiomers

when two isomers are mirror images of each other

alpha (α) particle

⁴ ₂He2+  is emitted from the nucleus

• A= decreases by 4, Z=decreases by 2

beta (β⁻) particle

0-1e an electron emitted from a nucleus when a neutron converts into a proton and a positron

• A = unchanged, Z = increase by 1

positron (β⁺)

positively charged “electron” emitted from a nucleus when a proton → neutron & β⁺

• A = unchanged, Z = decrease by 1

electron capture

0-1e one of the isotope’s own electrons crashes into the nucleus, converting a proton to a neutron

• A = unchanged, Z= decrease by 1

nuclear transmutation

bombarding a nucleus with high energy particles (alpha particles, protons, neutrons, other atoms)

nuclear fission

the process of breaking a large nucleus into smaller pieces

critical mass ( of fissionable material)

the amount of the isotope needed to self sustain a chain reaction once it’s initiated

• if there isn’t enough material, you have a subcritical mass

supercritical mass

an amount of fissionable material that speeds up the rate of fission

nuclear moderator

a substance that will slow down the speed of neutrons so they can be absorbed by the fuel & induce fission

radioactive tracers

compounds that have a stable element in a molecule with its radioactive version

• movement is tracked by the radiation emitted

moles → mass formula

mass (g) = moles x molar mass (g/mol)

mass → moles

moles = mass (g)/ molar mass (g/mol)

moles → atoms

atoms = moles x 6.022 × 1023

atoms → moles

moles = # of atoms/6.022 × 1023

nuclear fusion

the process of taking lighter elements, and turning them into heavier stable elements

s sub-shell

1 orbital with a maximum of 2 electrons

p sub-shell

3 orbitals with a maximum total of 6 electrons (2 per orbital)

d sub-shell

5 orbitals with a maximum total of 10 electrons

f sub-shell

7 orbitals with a maximum total of 14 electrons

ordering of sub-shell energies

1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p

n = principle quantum #

characterizes energy and size of an orbital

𝑙 = angular momentum quantum #

characterizes the shape and type of orbital

𝑙 = 0 → s

𝑙 = 1 → p

𝑙 = 2 → d

𝑙 = 3 → f

𝑚𝑙 = magnetic quantum #

characterizes the orientation of the orbital (and how many of each orbital type exist)

𝑚𝑙 = - 𝑙, -𝑙 +1 … -1, 0, 1. . . 𝑙 - 1, 𝑙

Helium [He] Nobel Gas Configuration

1s² (2 electrons)

Neon ([Ne] Noble Gas Configuration

1s²2s²2p⁶ (10 electrons)

Argon [Ar] Noble Gas Configuration

1s²2s²2p⁶ 3s²3p⁶ (18 electrons)

Krypton [Kr] Noble Gas Configuration

1s²2s²2p⁶ 3s²3p⁶ 4s² d¹⁰4p⁶ (36 electrons)

Xenon [Xe] Noble Gas Configuration

1s²2s²2p⁶3s²3p⁶ 4s² 3d¹⁰4p⁶ 5s² 4d¹⁰ 5p⁶ (54 electrons)

Radon [Rn] Noble Gas Configuration

1s² 2s² 2p⁶ 3s²3p⁶ 4s² 3d¹⁰4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ (86 electrons)

Ionic bond

electron(s) transferred completely from one atom to another (metal to non-metal) the resulting +/- charges attract each other

Covalent bond

electrons shared between atoms, come in three varieties:

Polar Covalent Bond

electrons shared between atoms, but one atom has a greater hold on the shared electrons, which makes the bond slightly charged

Electronegativity

an attempt to numerically quantify the “pull: an atom has on an electron in a bond, involves both:

ionization energy

energy required to remove an electron from an atom

electron affinity

energy change when an electron is added to an atom

A bond is ionic when the difference in electronegativity is:

EN > 1.8

A bond is polar covalent when the difference in electronegativity is:

EN = 0.4 - 1.8

A bond is covalent when the electronegativity is:

EN < 0.4

Lewis Structure Rules

H is always on the outside of a molecule (can only form one bond)

C is always the central atom

Otherwise, the central atom will have the lowest electronegativity

Average Bond Order

bond order of structure 1 + bond order of structure 2/ # of resonance structures

Polar molecule

a molecule with a asymmetric distribution of charge

Naming rules for binary ionic compounds (cation + anion)

metal cation keeps its name, nonmetal anion will add a suffix of “-ide”

Naming rules for binary covalent compounds

add a prefix that indicates the number of each atom present for both atoms

Single Replacement/Displacement Reaction

one element/ion replaces another in a compound

AX + Y → AY + X

Double Replacement/Displacement Reaction

two molecules “swap partners”

AX + BY → AY + BX

Decomposition Reaction

one molecule breaks down into two or more molecules

Z → X +Y

Combination (Synthesis) Reaction

two or more molecules combine to form a single new molecule

X + Y → Z

Combustion

a molecule reacts with naturally occurring oxygen to produce one or more molecules & heat

Spectator Ions

ions that appear on both sides of the equation, but don’t contribute to the reaction

D orbitals

P orbitals

S orbital

F orbitals

LEONA

loses electrons oxidation negative anode

GERPC

gains electrons reduction postive cathode

how to determine the anode

the metal higher in the EMF series, which is donating electrons

how to determine the cathode

the metal lower in the EMF series, which is accepting electrons

percent yield

actual amount of product/theoretical yield of product x 100%

enthalpy

a value (H) which gives a measure of energies related to molecules (such as heat energy “stored” in a molecule in bonds) and processes (such as chemical reactions)

ΔH_rxn = H of products - H of reactants

• if ΔH_rxn < 0, reactants had a higher total enthalpy than products

• if ΔH_rxn > 0, products had a higher total enthalpy than reactants

reaction mechanism

the sequence of steps molecules go through as they go from reactants → products

• the slowest rate-limiting step will control the rate of the overall reaction

collision theory

two molecules must collide with an energy greater than/equal to the activation energy

molecules must also collide in the proper spatial orientation so that right bonds can break/form between the right atoms

reaction rate

can be thought of as a function of molecular energy (of collision) & molecular orientation

reaction rate = (# of molecular collisions per unit time/energy ≥ E_a) x (proportion of collisions in which the colliding molecules are in the correct orientation)

concentration and reaction rates

the higher the # of molecules of the reactants, the more total collisions would occur, making the reaction faster

temperature and reaction rates

the higher the temperature, the faster molecules move

• the average speed of a molecule depends on the temperature the molecule is at & the molecular weight

rate constant

rate = (k) x (total # of collisions per unit time)

• is temperature dependent

• is used to quantify all things in a reaction that we can’t control

plausibility of mechanisms

for a proposed mechanism to be plausible, the experimentally measured rate law for the overall reaction must match the rate law of the proposed rate limiting step

catalyst

a substance that participates in a reaction, but isn’t permanently changed by the reaction

• it is a reactant, but gets returned as a product in a later step

types of catalysts

homogenous: a substance mixed in with the reactants

heterogenous: a surface upon which reactants absorb, react, and release from as a new species

enzymes: biological catalysts

enzymes

large biomolecules w/ specific active sites that allow an enzyme to selectively interact w/ a specific substrate molecule

chemical equilibrium

equilibrium is established when the rate of the forward reaction = the rate of the reverse reaction

at equilibrium, reactants are forming products while products are forming reactants, and the amounts don’t change

• rate = k_forward [A]_eq [B]_eq = k_reverse [W]_eq [X]_eq

k_eq depends on the equilibrium concentrations of all species and their stoichiometric coefficients in the overall reaction

equilibrium constant

for a general equilibrium reaction (at a given T)

• a A + b B ⇌ c C + d D

• K_eq = [C]_eq ^c x [D]_eq ^d / [A]_eq ^a x [B]_eq ^b

-if K_eq is large ( > 10³), [products] > [reactants]

-if K_eq is small ( < 10^-3), [products] < [reactants]

- if K_eq is moderate (10^-3 < K_eq < 10³ )

reaction quotient

if we mix concentrations of substances, we can know which way the reaction will go to reach equilibrium

• Q = [C]_actual ^c x [D]_actual ^d / [A]_actual ^a x [B]_actual

- if Q < K_eq, the reaction will make more product

- if Q > K_eq, the reaction will make more reactant

- if Q = K_eq, the reaction is already at equilibrium

le chatelier’s principle

if a reaction at equilibrium is disturbed, the reaction will shift direction as necessary to counteract the disturbance

• a A + b B ⇌ c C + d D

- add A or B or remove C and D = reaction will shift right toward products

- remove A or B or add C and D = reaction will shift left toward reactants

temperature and equilibrium

for an exothermic (ΔH_rxn < 0) reaction

• reactants ⇌ products + heat

- raising the temp will shift the reaction to the left to “consume” some of the added heat

- lowering the temp removes heat, reaction will shift to the left to produce more

for an endothermic (ΔH_rxn > 0) reaction

• reactants + heat ⇌ products

- raising the temp will shift the reaction to the right to “consume” some of the added heat

- lowering the temp removes heat, reaction will shift to the left to produce more

arrhenius acids and bases

acids: dissociate in water to form H⁺

• HA (aq) → H⁺ (aq) + A^- (aq)

bases dissociate in water to form OH^-

• MOH (aq) → M⁺ (aq) + OH^- (aq)

weak acid equilibrium

K_a = [H₃O⁺]_eq x [A^-]_eq / [HA]_eq

Bronsted-Lowry definition of an acid

a substance that donates a proton

Bronsted-Lowry definition of an base

substance that accepts a proton

water auto-ionization constant

K_w = 1 × 10^-14

when is a solution acidic?

[H₃O⁺] > 1 × 10^-7 moles/L, [OH^-] < 1× 10^-7 mol/L