Chemistry Module 4

wave, particle

light is made of

radiation

the rays and particles (alpha and beta) that are emitted by radioactive material

visible light, x rays, microwaves, tv/radio waves

Examples of electromagnetic radiation

wavelength, frequency, and amplitude

characteristics of waves

wavelength symbol

λ

frequency symbol

V

wavelength

the shortest distance between equal points on a wave

frequency

the number of waves that passes a given point per second

amplitude

Height of a wave from the origin to a crest

Speed of light

(3.00 x 10^8 m/s) c=λV (wavelength x frequency)

Waves models don't explain

why heated objects emit only certain frequencies of light at a given temp and why some metals emit electrons when light of a specific frequency shines on them

quantum

the minimum amount of energy that can be gained or lost by an atom

quantum concept

Matter can gain or lose energy only in small specific amounts called quanta

photoelectric effect

The emission of electrons from a metal when light shines on the metal

photon

a massless particle that carries a quantum of energy

Planck's constant

6.626 x 10^-34 Js

Formula for the energy of a photon

E=hv

atomic emission spectrum

the set of frequencies of the electromagnetic waves emitted by atoms of the element

increases

When the wavelength decreases the frequency ____

ground state

The lowest energy state of an atom

Bohr's contribution

Electrons moved in orbits (incorrect), the number assigned to each orbit of an electron is a quantum number

Bohr lacked

his model explained hydrogen's spectral lines but not any other element, although not 100% sure - evidence shows electrons do not move around nucleus in circular orbits

de Broglie equation

λ = h/mv, predicts that all moving particles have wave characteristics

The Heisenberg uncertainty principle

it is impossible to know exactly both the velocity and the position of a particle at the same time, the only quantity that can be known is the probability for an electron to occupy a certain region around the nucleus

4

the quantum mechanical model assigns ____ quantum numbers to atomic orbitals

principal quantum number

symbolized by n, indicates the main energy level occupied by the electron, as n increases the orbital becomes larger

1

an atoms lowest principal energy level is assigned a principal quantum number of ___

energy sublevels

principal energy levels contain

Aufbau Principle

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

Pauli Exclusion Principle

two electrons occupying the same orbital must have opposite spins

Hund's rule

single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals

valence electrons

Electrons on the outermost energy level of an atom which are added up

Hund's Rule

example of Whose Rule/principle

Aufbau Principle

example of whose rule/principle

Pauli Exclusion Principle

examples of whose rule/principle