MCAT - General Chemistry

1 m³

1000 L is equivalent to how many cubic metres?

1000 cm³

1 L is equivalent to how many cubic centimetres?

centimetre, cc

1 mL is equivalent to a cubic _____, which is equivalent to 1 ____

10^-10 m

1 angstrom is equivalent to…

kg/m³, g/cm³, mass/volume

The density of a subject (SI units = _____, but commonly expressed as _____) is calculated using…

1 g/cm³

1000 kg/m³ is equivalent to…

the molecule is expressed using the smallest whole numbers as a ratio

A chemical’s empirical formula is the formula in which…

NH4^+

The formula for the polyatomic ion ammonium is…

H3O^+

The formula for the polyatomic ion hydronium is…

CH3CO2^-

The formula for the polyatomic ion acetate is…

HCO3^-

The formula for the polyatomic ion bicarbonate is…

CN^-

The formula for the polyatomic ion cyanide is…

OH^-

The formula for the polyatomic ion hydroxide is…

NO3^-

The formula for the polyatomic ion nitrate is…

NO2^-

The formula for the polyatomic ion nitrite is…

ClO4^-

The formula for the polyatomic ion perchlorate is…

CO3^-

The formula for the polyatomic ion carbonate is…

SO4^2-

The formula for the polyatomic ion sulfate is…

SO3^2-

The formula for the polyatomic ion sulfite is…

PO4^3-

The formula for the polyatomic ion phosphate is…

6.02×10^23, link between atomic mass units and grams

Avogadro’s number is _______, which represents the…

12 grams

If the mass of carbon-12 is 12 amu, then a carbon-12 sample containing 6.02×10^23 carbon-12s has a mass of…

n = m/M

The formula for # of moles is…

g/mol, # moles of solute/# litres of solution

The formula for molarity (M, aka ____), is…

what proportion of reactants that react and products that are formed

Stoichiometric coefficients tell us…

how the atom’s “ownership” of its valence electrons changes when it forms a compound

Oxidation state is meant to indicate…

state of any element in its standard is 0, sum of states for neutral molecules is 0 and charged molecules is the charge, group 1 metals are +1 and group 2 metals are +2, fluorine is -1, hydrogen is +1 unless bound to a metal where it is -1, oxygen is -2, halogens are -1 and oxygen family are -2

The rules of assigning oxidation states, from highest to lowest priority, are…

highest electronegativity (F) of the list to lowest (H), H bonded to any others on the list is +1 and anything not on the list is -1

FONClBrISCH lists _______, therefore…

Z, number of protons in the nucleus

An element’s atomic number (__) represents…

A, number of protons and neutrons in the nucleus

An element’s atomic mass number (__) represents…

elements with a different number of neutrons than normal

Isotopes are…

weighted average of the masses of its normally occurring isotopes

The atomic weight of an element is a…

anion

An ion with a negative charge is called a(n)…

cation

An ion with a positive charge is called a(n)…

large nucleus becomes more stable by reducing the number of protons and neutrons by emitting an alpha particle

Alpha decay occurs when a…

mass number to reduce by 4 and atomic number to reduce by 2

Alpha decay results in the parent nucleus’…

neutron is converted to a proton or vice versa via the weak nuclear force

Beta decay occurs when a…

atomic number to increase by 1, electron

Beta negative decay results in the parent nucleus’ ________ and results in the release of a(n) ________.

atomic number to reduce by 1, positron

Beta positive decay results in the parent nucleus’ ________ and results in the release of a(n) _______.

electron capture, unstable nucleus captures an electron from n=1 and converts a proton to a neutron

The third form of beta decay, ________, occurs when an…

atomic number to reduce by 1

Electron capture results in the parent nucleus’…

nucleus in an excited energy state relaxes to ground state by releasing photons (gamma particles)

Gamma decay occurs when a…

exponentially, half-life

The amount of a radioactive substance decreases _______ with time, determined by the substance’s _____.

N=N₀(1/2)^T/t_1/2 or N=N₀e^-kt , decay constant, total time

The equation for exponential decay is _______, where k = _____ and T = _____

nuclear binding energy, energy that was released when the nucleons were bound by the strong nuclear force, some mass is converted to energy, sum of the individual nucleons is more than that of the combined nucleus, mass defect

Every nucleus that contains protons and neutrons has a ________, which is __________. When nucleons bind together to form a nucleus _______, thus the ________. This is referred to as…

delta m = sum of individual nucleons - mass of nucleus

The formula for mass defect is…

E_B=(delta m)c² , speed of light 3×10⁸ m/s

The formula for nuclear binding energy is _______, where c = _______.

9×10¹⁶

1 kg is equivalent to ______ Joules

1.66×10^-27

1 amu is equivalent to _______ kg

1.6×10^-19

1 eV is equivalent to _______ J

E_photon= hf = h(c/lambda)

The energy of photons emitted as part of an element’s emission spectrum can be calculated using…

contains only one electron

A Bohr atom is an atom that…

E_n=(-2.178×10^-18 J)/n² , energy level

The formula for energy at an energy level in the Bohr model is _______ where n = _______.

electrons occupy the lowest energy orbital available

The Aufbau principle states…

electrons in the same subshell occupy orbitals singly before pairing

Hund’s rule states…

an orbital can contain up to two electrons

The Pauli exclusion principle states…

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

The order of filling orbitals is…

all electrons are spin-paired, repelled by

An atom is diamagnetic when ______, and are _______ an external magnetic field.

not all electrons are spin-paired, attracted to

An atom is paramagnetic when _______, and are _______ an external magnetic field.

have the same electron configuration

Atoms are isoelectronic when they…

alkali metals, s, ns¹

Group I is the _____, which is a part of ___ block (valence configuration ____).

alkaline earth metals, s, ns²

Group II is the _____, which is a part of ___ block (valence configuration ____).

halogens, p, ns²np⁵

Group VII is the _____, which is a part of ___ block (valence configuration ____).

noble gases, p, ns²np⁶

Group VIII is the _____, which is a part of ___ block (valence configuration ____).

representative elements, transition metals, rare earth metals

The s and p blocks are the ______, the d block is the ______, and the f block is the _______.

Nuclear Shielding

Each filled shell between the nucleus and valence electrons protects the valence electrons from the full effect of the protons in the nucleus, thus the electrical pull from the protons is reduced by the negative charges of the filled electron shells

effective reduction of positive elementary charge from Z to Z_eff

Nuclear shielding results in…

decreases, increases, X+ < X < X-

Moving from left to right across a period, atomic radius _____. Moving down a group, atomic radius _____. For atomic radius of ions…

amount of energy necessary to remove the least tightly bound electron

The first ionization energy is the...

higher

The second ionization energy will always be _____ than the first ionization energy.

energy associated with the addition of an electron to an isolated atom, negative, positive

Electron affinity is the _________. If energy is released when an electron is added the EA is _____; if energy is required to add an electron the EA is ______.

an atom’s ability to pull electrons to itself when it forms a covalent bond

Electronegativity is a measure of…

F > O > N ~ Cl > Br > I > S > C ~ H

The order of the nine most electronegative elements is:

increases

Moving from left to right across a period or up a group, ionization energy _____.

increases

Moving from left to right across a period or up a group, electronegativity _____.

more negative

Moving from left to right across a period or up a group, electron affinity becomes _____.

HX, HX → H+ + X-

A binary acid has the structure ____ and dissociates in water as follows:

stability of the conjugate base (X-)

Generally speaking, the ease with with which an acid (HX) donates its H+ is directly related to…

more stable the anion, negative charge can be delocalized and stabilized, acidity increases down a group or family

Moving from left to right across a period, the more electronegative the element bearing the negative charge is, the ________. For groups, the larger the anion, the more the __________. Therefore…

Free radicals

Molecules with unpaired valence electrons

Formal charge

Hypothetical charge assigned to each atom in a Lewis structure, assuming that all bonding electrons are shared equally between bonded atoms

FC = V - (1/2)B - L where V is number of valence electrons, B is number of bonding electrons, and L is number of lone pairs

The formula for formal charge is…

break a bond homolytically, the higher the bond order the shorter and stronger the bond (e.g. C-C vs C=C)

Bond disassociation energy (BDE) is the energy required to ________. For similar bonds, the ________.

1 electron of the bond being broken going to each atom of the molecule, resulting in 2 free radicals

Homolytic bond cleavage results in…

both electrons that make up the bond end up on the same atom, resulting in a cation and anion

Heterolytic bond cleavage results in…

only non-bonding electrons, double bonds, and triple bonds may move around

Resonance structures are 2 or more structures where…

uneven, even

A bond is polar when the electron density between two nuclei is ______. A bond is nonpolar when the electron density between two nuclei is ______.

Coordinate covalent bond

Formed when one atom donates both of the shared electrons in a bond

valence shell electron pair repulsion, since electrons repel one another, electrons pairs whether bonding or nonbonding attempt to move as far apart as possible

The rule of VSEPR (________) theory is:

linear, trigonal planar, or tetrahedral

According to VSEPR theory, a molecule where the central atom has no lone pairs can form the following geometry:

bent or trigonal pyramidal

According to VSEPR theory, a molecule where the central atom has 1 lone pair can form the following geometry:

bent

According to VSEPR theory, a molecule where the central atom has 2 lone pairs can form the following geometry:

add the number of attached atoms to the number of non-bonding electron pairs, which equals the number of orbitals combined to make the new hybridized orbitals

To determine the hybridization for most atoms in simple molecules…

sp, 180 degrees, linear

The the number of electron groups (# atoms + # lone pairs) equals 2, then the hybridization is _____, the ideal bond angle is _____, and the orbital geometry is ______.

sp², 120 degrees, trigonal planar

The the number of electron groups (# atoms + # lone pairs) equals 3, then the hybridization is _____, the ideal bond angle is _____, and the orbital geometry is ______.

sp³, 109.5 degrees, tetrahedral

The the number of electron groups (# atoms + # lone pairs) equals 4, then the hybridization is _____, the ideal bond angle is _____, and the orbital geometry is ______.

2 electrons localized between 2 nuclei formed by end-to-end overlap of one hybridized orbital from each of the atoms in the bond

A sigma bond consists of…

proper, parallel side-to-side alignment of 2 unhybridized p orbitals on adjacent atoms

A pi bond is formed by…

Ion-dipole forces

Formed by the attraction between polar molecules and ions

Dipole-dipole forces

Formed by the attraction between the positive end of one polar molecule and the negative end of another polar molecule