ap chem unit 1

electron affinity

the energy change that occurs when an electron is acquired by a neutral atom

electron cloud model

model of atom in which the electrons seem to form a cloud as they move around the nucleus

Gd in MRI

it has 8 unpaired electrons

sheilding effect

the electrons of previous energy levels shields the pull of the nucleus on outer level electrons (increases going down and constant going across)

ionization energy

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

electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons

Dalton atomic theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

PEL formula

2n^2

quantum jump

an abrupt transition of an electron, atom, or molecule from one quantum state to another, with the absorption or emission of a quantum.

dual nature of an electron

an electron has characteristics of a particle as well as a wave

Aufbau Principle

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

Hund's Rule

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, each with opposite spin direction

orbital notation

a diagramic representation that uses dashes and arrows to show the principal energy levels and sublevels for all the electrons in an atom

sublevel notation

ex: for sodium, 1s2 2s2 2p6 3s1. for cesium, 6s1

Hund's Rule of Maximum Multiplicity

When two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs

Oxidation State Rules

1. Elements in their elemental form are zero oxidation state (Ex. Na, He, O2, H2, N2, P4, S8, O3 = 0 oxidation state).

2. Group 1 metals are +1, Group 2 metals are +2 in compounds.

3. Hydrogen is +1 when bonded to nonmetals and -1 when bonded to metals.

4. Transition elements' oxidation numbers must be determined from the other elements in the compound.

5. The most electronegative atoms get their typical oxidation state.

6. When assigning oxidation numbers, the last element assigned gets whatever number balances the charge for the entire compound.

particle

a minute portion of matter

gram formula mass

the formula mass expressed in grams instead of atomic mass units

wave properties

frequency, wavelength, amplitude and period.

energy from waves can cause

electrons to transition between PEL's
electrons to be removed (ionization)
bonds to be broken (bond energy)
atoms (atoms, molecules ) to vibrate + rotate faster

Light and electromagnetic spectrum

We have a defined light as an electromagnetic wave. These waves can be produced by a variety of sources. Because these waves have different wavelengths and electromagnetic wave spectrum is produced. The electromagnetic Spectrum is arranged in terms of decreasing wavelength.

EMS

radio micro infrared visible ultraviolet Xray gamma

one photon

one wave

dilution equation

M1V1=M2V2

Beer-Lambert Law

Used to relate the concentration of colored solutions to the amount of visible light they absorb.

periodic law

the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements

gasses at stp

H N O F Cl

Liquids at STP

Hg, Br

diatomic elements

H2, N2, O2, F2, Cl2, Br2, I2

Columb's Law

The higher the charges, the more force. F=K(q1q2/d2) (D=Distance, Q= Charge of 2 objects, K= Proportionality constant)

effective nuclear charge

the net positive charge experienced by an electron in a many-electron atom; this charge is not the full nuclear charge because there is some shielding of the nucleus by the other electrons in the atom

effective nuclear charge trend

increases across a period, decreases down a group

ionization energy trend

decreases from top to bottom in a group; increases from left to right in a period

electron affinity trend

increases across a period, decreases down a group

electronegativity trend

decreases from top to bottom in a group; increases from left to right in a period