Mcat Chemistry Equation Sheet

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MCAT Chemistry Equation Sheet
ORBITALS AND ELECTRONS
1.
molecules are very small compared to the
INTERMOLECULAR FORCES
distance b/w them
Quantum numbers descriptions
2.
molecules are continuously moving
D
F
:
ISPERSION
ORCES
Describe the attraction between the negatively
3.
pressure of the gas – collisions of the
Quantum
Description
Possible
charged electron cloud of one molecule and the
number
values
molecules with container walls
positively charged nuclei of neighbouring molecules
Principal quantum
energy level
n=1, 2, 3….
D
F
:
IPOLAR
ORCES
4.
molecules do not experience intermolecular
number (n)
Describe the attraction between the negatively
Angular
orbital shape (s,
l = 0, to …n-
forces
charged end of a polar molecule and the positively
momentum
p, d, f)
1
charged ends of neighbouring polar molecules
∝ T
5.
KE
quantum number
ave
H
B
:
YDROGEN
ONDING
PV = nRT
(l)
Involves lone pairs of electrons on an
Ideal-gas law:
Magnetic quantum
orbital
m = -l to +l
electronegative atom of one molecule and a polar
P
V
P
V
Combined gas law:
number (m)
orientation (p
,
=
bond to hydrogen in another molecule, they are
x
1
1
2
2
p
, p
)
T
T
confined to molecules that contain O, N, and F
y
z
1
2
Spin quantum
describes spin of
m
= + ½ or -
atoms.
s
V
V
number (m
)
electron
½
Charles’ law:
=
P = const
P
:
OLARIZABILITY
s
1
2
The ease with which the electron clouds are
T
T
1
2
distorted
Each electron has a unique set of quantum
= P
Boyle’s law:
P
V
V
T = const
M
S
:
OLECULAR
OLID
1
1
2
2
numbers.
Molecules in molecular solids are held in place by
P
P
the types of forces: dispersion forces, dipolar
No ones’ Law:
=
V = const
ELECTRONIC CONFIGURATION
1
2
interactions, and/or hydrogen bonds
T
T
1
2
M
S
:
ETALLIC
OLID
Electron configuration: describes the location of all
STP – standard temperature (0°C or 273.15 K) and
Atoms in metallic solids are held in place by
of the electrons in an element. e.g. Carbon =
delocalised bonding
pressure (1 atm)
2
2
2
1s
2s
2p
N
S
:
ETWORK
OLID
Contains an array of covalent bonds linking every
1 mol of ideal gas occupies V = 22.4 L
Heisenberg Uncertainty Principle: the
atom to its neighbours
standard conditions - 25°C and 1 atm
position and momentum of a particle cannot
I
S
:
ONIC
OLID
both be exactly known at the same time.
Contains cations and anions, attracted to one
Dalton’s law of partial pressure (mixture of the gases)
Pauli exclusion principle: no two electrons
another by coulombic interactions
+ p
+K+ p
P= p
in an atom can have the same set of four
A
B
N
quantum numbers (n, l, m, m
) which means
SOLUTIONS
s
χ
=
⋅ P
that each orbital with quantum numbers (n, l,
p
A
A
m) can hold at most two electrons with
opposite spins.
n
N
moles of solute/volume of
χ
=
=
A
A
molarity (M)
solution. M=n/V
A
n
N
Hund’s rule: when electrons added to
molality (m)
moles of solute/kg of solvent
total
total
orbitals of equal energy, a single electron
moles of solute/total moles
mole fraction (χ)
G
RAHAM
S LAW OF EFFUSION
enters each orbital before a second electron
mass of solute x 100/ total mass
with opposite spin enters any orbital. The
mass percent
1
v
m
of solution
=
spins remain parallel if possible. e.g.
=
2
A
B
KE
m
v
6
parts per million
mass of solute x 10
/total mass
A
A
A
Nitrogen
2
v
m
(ppm)
of solution
↑↓
↑↓
B
A
N =
Raoult’s Law (distillation)
1s
2s
2p
2p
= T
P =
x
y
= KE
KE ∝ T
o
at
T
b/c
, but
X
P
KE
2p
z
A
A
A
A
B
A
B
P
Where
= partial pressure of A in solution
≠ v
= T
A
v
at
T
Aufbau Principle: dictates the order in
X
= mole fraction of A in the liquid
A
B
A
B
A
which orbitals fill. Some exceptions occur in
0
P
= vapour pressure of pure A
What leads to the gas “ideality”: high T & low P & lower
A
the transition elements.
1s
molecular weight or small size of gas molecules
2s 2p
Colligative properties (melting/boiling points
Real gases:
3s 3p 3d
etc)
4s 4p 4d 4f
have intermolecular attractions (non-elastic
Freezing point depression: salt on the sidewalk in winter
5s 5p 5d 5f
collisions) called Van der Waals forces
lowers the freezing point of H
O to prevent the water
6s 6p 6d 6f
2
from freezing
contain molecules that have volume (or
∆T
THE GAS PHASE
= k
mi
f
f
measurable size)
Boiling point elevation: salt in pasta water increases the
boiling point of H
O so that the water boils hotter (and
2
2
U
P
:
n
NITS OF
RESSURE
(
)
your pasta cooks more quickly).
+ a
⎟ ⋅ V
− nb
= nRT
P
∆T
1atm = 760 mmHg = 760 torr = 101.325 kPa =
= k
mi
real
real
2
b
b
V
1.01325 barr
Osmotic pressure: increase in pressure due to a solvent
crossing a membrane into a more concentrated solution
ΠV=nRT
I
DEAL GAS POSTULATES
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