Honors Chemistry Unit 5 - Electrons in Atoms

waves

the propagation of energy through a medium

wavelength

the distance between successive crests in a wave

frequency

the number of wave cycles that occur per second

amplitude

the change between the origin of the wave and its crest

waves by largest to smallest wavelength

radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray

waves with the largest wavelengths

radio waves

waves with the smallest wavelengths

gamma ray waves

speed of light

3 × 10^8 m/s

photons

massless particles of light that carry energy

wave-particle duality of light

light behaves as both a particle and a wave

wave with second longest wavelength

microwave

wave with third longest wavelength

infrared

wave with fourth longest wavelength

visible

wave with fifth longest wavelength

ultraviolet

wave with sixth longest wavelength

x-ray waves

speed of a wave equation

speed = wavelength * frequency

symbol for wavelength

lambda

symbol for frequency

omega

unit for wavelength

meters

unit for frequency

1/second and hertz

equation for speed of light

speed of light = wavelength * frequency

how photons are measured

joules

equation for the energy of a single proton

energy = Planck’s constant * frequency

violet light

short wavelength, high frequency

red light

longer wavelength and lower frequency

photoelectric effect

the emission of electrons when electromagnetic radiation strikes a material

relationship between frequency of light and release of kinetic energy

the higher the frequency of light, the higher kinetic energy

Bohr Model

Electrons can only exist in fixed orbits around the nucleus called energy levels that add extra stability to their positions. These orbits are quantized, or exist at regular intervals (no electrons can be in between these energy levels). The farther an energy level is from the nucleus, the more energy it has. 

quantization

states electrons exist in discrete orbits.

what happens when an electron relaxes

it releases a photon equal to the difference in energy between the energy levels.

how an electron can be excited

the absorption of energy

sources of energy that excite electrons

light (photons), heat, electricity

atomic emission spectrum

a characteristic blend of visible colors caused by the excitation of atoms of an element

atomic absorption spectrum

the visible colors of photons required to excite elements of an electron

De Broglie’s equation

the wavelength of an object = Planck'‘s constant divided by the product of mass and velocity

quantum mechanics

a theory that ties together subatomic particles, quantization, and Heisenberg’s uncertainty principle.

Heisenberg’s uncertainty principle

you can only know an electron’s energy/momentum or position, never both

most important thing to know about an electron

its momentum/energy

orbital/electron cloud

an area of 3-D space where there is a 95% chance of finding an electron.

Aufbau principle

electrons tend to occupy orbitals in lower energy levels (shells) before those of higher energy

Pauli exclusion principle

no two electrons can have the same quantum numbers/can be spinning the same way

Hund’s rule

electrons fill orbitals halfway in a sublevel (subshell) before pairing with other electrons

quantum number

gives information about where an electron most likely is in an atom.

principal quantum number

Indicates how far away an electron is from the nucleus

angular/azimuthal quantum number

Indicates the shape of the orbital in which the electron resides

magnetic quantum number

Specifies the exact area/oriental of the orbital in which the electron resides

orbital diagrams

pictorial diagrams that not only show the energy levels and sublevels of electrons, but also their orientation and spin.

letters used in orbital diagrams

s, p, d, f

electron configurations

a summary of the distribution of electrons around an atom in shorthand notation.

noble gas notation

a shorthand way to express electron configurations and orbital diagrams by condensing the electrons in the previous noble gas into a symbol with brackets.

noble gases

a family of elements in group 18 on the periodic table that are almost completely unreactive.

valence electrons

electrons in the outermost energy level

core electrons

electrons that are not in the highest shell

electron dot notation

a way to represent an atom of an element by using the chemical symbol of the element surrounded by the number of valence electrons that element has.