MCAT basics

3D physical space

anything that has mass and occupies space- cannot be created/destroyed in a chemical reaction

the measure of the amount of matter in an object

mass per unit volume

energy is the ability to do work- cannot be created/destroyed, but can swap between KE and PE
kinetic energy- energy from motion
potential energy- energy the object possesses due to its location

the smallest unit of an element that retains the chemical properties of the element

the smallest component of a compound (different elements) that retains the properties of that compound

a pure substance composed of multiple atoms chemically combined in a known ratio

an atom/group of bonded atoms that carries and electrical charge
cation- +
anion- -

the number of protons in the given element

gives the number of protons and neutrons within a given isotope of an atom

atoms with the same atomic number, but different mass numbers (different numbers of neutrons)

the regions of space around a nucleus that have a nonzero probability of having an electron in a nonspecific energy state - each can hold 2 electrons

the most probable distance of an electron from the nucleus- electrons within the same n are in the same "shell"
can be all positive integers

the shape of the orbital (s, p, d f, etc)
electrons are in the same "subshell"- each has (2l +1) orbitals that can hold 2 electrons
allowed: 1(s), 2(p), 3(d)... n-1

for a given subshell, it gives you which (2l+1) orbital an electron is in
allowed: 0, +-1, +-2... +/- L

shows the electron spin direction (up/down)
allowed values: +/- 1/2

the electrons closer to the nucleus reduce the nuclear attractive force for electrons farther than the nucleus

the nuclear charge experienced by an electron after the effects of shielding have been removed (Zeff)- always less than the actual nuclear charge (z)

d orbitals

all orbitals must have one parallel spin electron before any of them get a pair

no 2 electrons can have the same 4 quantum numbers

metals (good conductors of heat/electricity, tend to lose electrons to form cations)
nonmetals- tend to form anions, poor conductors
mtalloids- intermediates between metals/nonmetals, with chemical and physical properties of both

half the distance between the nuclei of 2 neighboring atoms of an elements
(higher atomic number= more compact)

rows on a periodic table are called Periods.
Columns are called groups

the energy required to remove an electron from the highest energy shell of an atom [increases traveling across a period (full shells), decreases down a group (larger)]

the ability of an atom in a molecule to attract electrons
(increases across a period, decreases down a group)

a bond formed when 2 elements share valence electrons so both gain full valence shells- can be 1x, 2x, 3x

oppositely charges ions bond together, forming a lattice structure where both shared electrons are are almost completely associated with the more electronegative atom

cations held together in a crystal lattice by delocalized electrons

half the number of electrons shared in a covalent bond- ex: 2 electrons form a single bond. A double bond is shorter than a single

if one atom is more electronegative, it pulls the shared electrons more tightly. This creates a polarity in the bond

used to determine the shape of a molecule- shows how electrons pair arrange themselvs as far apart from one another as possible to minimize electron-electron interaction

a theory that bond from through the spacial overlap of orbitals containing valence electrons

linear (SP hybridized), trigonal planar (1S, 2P), tetrahedral (SP3), trigonal bipyramid (DSP3), octahedral (D2SP3)

mixtures of individual orbitals, neither gaining nor losing orbitals in the process. each hybrid can hold 2 electrons

sigma- bonds formed by the head-on overlap of sp, sp2, or sp3 orbitals with each other or the 1s of hydrogen
pi bonds are formed from the sideways overlap of p orbitals

the weakest type of cohesitve force- attracted forces between 2 transient dipoles caused by random changes in electron distribution- affects all molecules

attractive forces between the permanent dipoles or polar molecules- neighboring molecule orient themselves to align to these forces

a type of dipole-dipole interaction involving molecules containing hydrogenattached to a high EN atom (ex: O, N)with lone e- pairs- the H carries a partial positive and the pair carry a partial negative, allowing interaction with other molecules

interactions in which oppositely charged species attract each other (strongest cohesive force)

London, Dipole/dipole, Hydrogen, and electrostatic forces

one mole= 6.02x 10^23 particles

the mass of one mole of particles

the mass (in amu) of one molecule of a compound

molecular shows the actual number of atoms of each element present in a molecule, the empirical shows the relative ration
C6H12O6 vs CH2O

the reactant that is supplied in an amount smaller than the stoichiometric relation to any of the other reactants- determines the maximum yield

(experimental yield)/(theoretical yield) x 100%

the amount of a given product produced if all of a limiting reagent is used