Chemistry 115 Exam 2

Electromagnetic Spectrum

All of the frequencies or wavelengths of electromagnetic radiation

Electromagnetic Spectrum Pneumonic Device

Rich Men In Vegas Use Expensive Girls

Longest wavelength in EM

radio waves

lower energy state to higher energy state

photon absorption

higher energy state to lower energy state

photon emission

Bohr Equation

-2.18E-18(Z^2/n^2)

energy density

pictoral representation for a given energy sublevel of the probability of the electron lying within that region

radial proabability

energy density diagram as a plot

quantum mode of atoms

atoms only have certain allowed energy states

principal quantum number (n)

indiciates size and energy level

angular momentum quantum number (l)

from 0 to n-1, gives sublevels into which energy level is divided, also relates to shape of the orbital

magnetic quantum number (ml)

describes 3D orientation of the orbital in the space around the nucleus

what does the total number of ml values tell you

the number of orbitals in that energy level

spin quantum numbers (ms)

+1/2 or -1/2, corresponds to the two possible directions of the electrons magnetic field

p orbital shape

peanut

s orbital shape

sphere

d orbital shape

4 leaf clover

f orbital shape

flower

aufbau principle

An electron occupies the lowest-energy orbital that can receive it

pauli exclusion principle

An atomic orbital may describe at most two electrons, each with opposite spin direction, no 2 - can have the the same energy level

hunds rule

all orbitals will be singly occupied before any is doubly occupied

periodic table groups

vertical columns

periodic table periods

horizontal rows

alkali metals

group 1

alkali earth metals

group 2

transition metals

groups 3 - 12

metalloids

along the periodic table staircase

periodic table group 17

halogens

periodic table group 18

noble gas

inner electrons

noble gas and all completed energy levels

outer electrons

Electrons that occupy the highest energy level

valence electrons

dame as outer for main groups (ns) but ns and (n-1)d for transition elements

electron configuration of ions in the main group

lose ns/np

electron configuration of ions in the transition group

lose ns and (n-1)d

transition element stability rule

sometimes upgrade s block to fill more stable d5 or d10

paramagnetic

dimagnetic

all electrons are paired

lewis symbols dots

valence electrons

lewis symbol lone pairs

no bonds

lewis symbol bonded piars

shared electrons

atomic radius

size of an atom

ionic radius

Distance from the center of an ion's nucleus to its outermost electron

atomic radius trend

increases down and to the left

ionic radius trend

decreases across a period and increases down a group, anions are larger cations are smaller

groups 1 and 2

low IE small EA, lose e- readily strong reducing agents and become oxidized

groups 16 and 17

high IE high EA, gain e- strong oxidizing agents and become reduced

oxidation

electron loss

reduction

electron gain

ionization energy

The amount of energy required to remove an electron from an atom

ionization energy trend

increases up and to the right

electron affinity

the energy needed to remove an electron from a negative ion to form a neutral atom or molecule

electron affinity trend

increases up and to the right

main group metals (acid or basic)

transfer electrons to oxygen, so their oxides are ionic -> act as bases

nonmetals (acid or basic)

share electrons with oxygen, so nonmetal oxides are covalent -> they form acids

amphoteric

act as acids or bases, some metals and metalloids

more metallic (larger size, smaller IE)

oxides are more basic

less metallic (smaller size, higher IE)

oxides are more acidic

ionic bond

metal + nonmetal, transfer electrons, (+)(-) attraction, not molecules

covalent bond

both nonmetal, shared attraction, attraction between e- and nucleus, molecules

octet rule

8 is more stable, or 2 for H/Li

bond order

the number of shared electron pairs between two atoms

bond strength/energy

energy needed to break bond in 1 mol of gaseous molecule

bond length

distance between nuclei of two bonded atoms

relationship bond order, length, energy

as bond order increases energy increases and length decreases

lattice energy

the energy required to separate 1 mol of the ions of an ionic compound

enthalpy of reaction calculation

hess's law and bond energy of reactants - bond energy of prodcuts

compuitng lattice energy =

heat of formation = hess law - h lattice

lattice energy and ion size

Increases with the decreasing size of the ion

lattice energy and ion charge

- Lattice energy increases with the charge on the ions

lattice energy and electronegativity

lattice energy increases as lattice energy increases

molarity

moles solute / L solution

molality

moles solute / mass solvent

conversion between molarity and molality

using density

percent yield

(Actual yield / theoretical yield) * 100

percent error

( (actual - expected) / (expected) ) * 100

beer lambert law

Used to relate the concentration of colored solutions to the amount of visible light they absorb. A = e l c

beer lambert law A

absorbance

beer lambert law e

molar absorptivity constant: different for each compound and wavelength; units=L/mol*cm

beer lambert law l

path length: distance light passes through solution (typically 1 cm for spectroscopy)

beer lambert law c

solution concentration

photoelectric effect

light hits metal above threshold -> electrons ejected when struck by photons, happens almost instantly

what is polarity caused by

electronegativity difference

wavelength of max absorbance

optimal wavelength for spectrophotometric experiment

blank use in spectrophotometric experiment

used to ignore device walls and solvent

concentration and solution shade

higher concentration results in darker shade

spectrophotometry graph

absorbance vs concentration

E when looking at moles

E = Nhc / wavelength

isoelectronic

same electron configuration