CHE115 Review 1 Prep

group 1

alkali metals

group 2

alkaline earth metals

group 18

noble gasses

group 17

halogens

isomer

molecule w/ same chemical formula but different molecular structures

structural isomer

compounds in which the molecules differ in how the atoms are connected

percent composition

percentage by mass of each element in the compound

sigfig multiplication/division rule

retain the fewest number of significant digits among your starting values

sigfig addition/subtraction rule

do the math with all digits then round up to smallest value (largest decimal place) of significance

molarity equation

C1V1 = C2V2

Pauli exclusion principle

no two electrons in the same atom can have exactly the same set of all 4 quantum numbers

values allowed for n

greater than or equal to 1, up to infinity

values allowed for l

greater than or equal to 0, less than or equal to n-1

values allowed for m_l

greater than or equal to -l, less than or equal to l

values allowed for s

-1/2, 1/2

what does n determine

shell, the general region for the value of energy for an electron on the orbital

what does l determine

subshell, the shape of the orbital

what does m_l determine

orientation of the orbital

what does s determine

direction of the intrinsic quantum “spinning” of the electron

shielding

when electrons that are closer to the nucleus slightly repel electrons that are farther out, offsetting the more dominant electron-nucleus attractions slightly

Aufbau principle

electrons fill atomic orbitals from the lowest available energy level up to higher levels to create the most stable electron configuration

hunds rule

the lowest energy configuration for an atom with electrons within a set of degenerate orbitals is that having the macimum number of unpaired electrons

effective nuclear charge, Zeff

the pull exerted on a specific electron by the nucleus, taking into account any electron-electron repulsions

ionization energy

the amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state

electron affinity

the energy charge for the process of adding an electron to a gaseous atom to form an anion

photoelectric effect

the emission of electrons from a material's surface when light or other electromagnetic radiation shines on it

ionic bonds

electrostatic forces of attraction between oppositely charged cations and anions

covalent bonds

the mutual attraction of atoms for a shared pair of electrons. formed between 2 atoms when both have similar tendencies to attract electrons to themselves

degenerate

having identical energies

Valence Shell Electron Pair Repulsion Theory (VESPR theory)

Assumes that electron pairs in the valence shell of an atom will adopt an arrangement that minimizes repulsions between these electron pairs by maximizing the distance between them

angles in trigonal bipyramidal (central atom connected to 5 others)

90º, 120º

angles in octahedral (central atom connected to 6 others)

90º, 180º

equation for bond dipole moment

M = Qr; Q=magnitude of partial charges; r = distance between charges

sigma bond

covalent bond in which the electron density in concentrated in the region along the internuclear axis; that is, a line between the nuclei would pass through the center of the overlap region

single bonds in lewis structures = sigma bonds in valence bond theory

pi bond

type of covalent bond that results from the side-by-side overlap of 2 p orbitals

hybridization

the process of combining the wave functions for atomic orbitals