AP Chemistry Unit 2

(Left out electron affinity sorry)

alchemy

Attempts (scientific or otherwise) to change

cheap metals into gold

robert boyle

First “chemist” to perform quantitative

experiments

george stahl

Phlogiston flows out of a burning material.

joseph priestley

discovered oxygen gas, “dephlogisticated

air.”

Dalton’s Atomic Theory - 1st Rule

Each element is made up of tiny particles

called atoms.

Dalton’s Atomic Theory - 2nd Rule

The atoms of a given element are

identical

Dalton’s Atomic Theory - 3rd Rule

Chemical compounds are formed when atoms combine with each other.

Dalton’s Atomic Theory - 4th Rule

Chemical reactions involve reorganization of

the atoms

JJ thompson

postulated the existence of electrons using cathode ray tubes

Law of conservation of mass (Lavoisier)

Mass is neither created nor destroyed

Law of definite proportion (Proust)

A given compound always contains exactly the same proportion of elements by mass

Law of multiple proportions (Dalton)

When two elements form a series of

compounds, the ratios of the masses of the

second element that combine with 1 gram of

the first element can always be reduced to

small whole numbers

Avogadro’s Hypothesis

At the same temperature and pressure, equal volumes of different gases contain the same number of particles.

Electromagnetic Radiation

Radiant energy that exhibits wavelength-like behavior and travels through space at the speed of light in a vacuum.

wavelength (lambda)

distance between two peaks in a wave

frequency (nu)

number of waves per second that pass a given point in space

speed of light (c )

2.9979 × 10^8 m/s

wavelength and frequency have what kind of relationship?

indirect relationship

state the units:

speed of light = (freq.)(wavel.)

m/s = (s^-1)(m)

planck’s constant

6.626 × 10^-34 Js

delta E (change in energy)

hc/lambda

h

planck’s constant (in equations)

c

speed of light constant

de Broglie’s equation

lambda = h/mv

unit for m (mass) in de Broglie’s equation

kg

unit for v (velocity) de Broglie’s equation

m/s

mass of an electron

9.11 × 10^-31 kg

Ground State

the lowest possible energy state for an

atom (n = 1)

Quantum model

the electron in a hydrogen atom moves around the nucleus in certain allowed circular orbits

delta E

E final state - E initial state

Bohr Model Equation

E = -2.178 × 10^-18 J (1/n²)

Bohr Model Equation (If energy level change)

E = -2.178 × 10^-18 J (1/n_final² - 1/n_initial²)

Pauli Exclusion Principle

In a given atom, no two electrons can have the same set of four quantum numbers

Aufbau Principle

As protons are added one by one to the nucleus to build up the elements, electrons are similarly added to these hydrogen-like orbitals.

Hund’s Rule

The lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals.

Valence Electrons

The electrons in the outermost principle

quantum level of an atom.

Coulomb's Law

an electron in a given shell will require a

certain energy to be separated from the atom

atomic size trend

Size goes UP on going down a

group

Covalent atomic radii

Determined from the distances between atoms in covalent bonds

Metallic radii

Obtained from half the distance between metal atoms in solid metal crystals

ionization energy

energy required to remove an electron from an atom in the gas phase.

Beer - Lambert Law

A = abc

“a” in the Beer - Lambert Law

molar absorptivity (1/M.cm)

“b” in the Beer - Lambert Law

path length (cm)

“c” in the Beer - Lambert Law

concentration (M or mol/L)

optimal wavelength

lambda MAX