Chemistry Pre -IB CH 4

radiation

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

electromagnetic radiation

form of energy that exhibits wave-like behavior as it travels through space

wavelength

shortest distance between equivalent points on a continuous wave

frequency

number of waves that pass a given point per second

amplitude

wave’s height from origin to crest

electromagnetic spectrum

all forms of electromagnetic radiation

quantum

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

Planck’s constant

h, value = 6.626 × 10 ^ -34 J s

photoelectric effect

photoelectrons emitted from metal’s surface when light at or above a certain frequeny shines on surface

photon

massless particle that carries a quantum of energy

atomic emission spectrum

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

Rutherford’s nuclear atomic model is incomplete because…

1. didn’t explain how electrons are arranged around the nucleus

2. didn’t show why negative electrons aren’t pulled into the nucleus

3. didn’t account for differences/similarities in chemical behavior among various elements

Relations of energy & frequency of electromagnetic radiation

they increase together

Relations of wavelength & frequency

as one increases the other decreases

EQ for speed, frequency and wavelength

c = ƛv, c = speed, v = frequency, ƛ = wavelength

Wave model of light failed to explain

1. why heated objects emit certain frequencies of light at a given temperature

2. why some metals emit electrons when light of specific frequency shines on them

Planck’s quantum concept

matter can gain or lose energy only in small, specific amounts called quanta. A quantum is the minimum amount of energy that can be gained or lost by an atom

Planck vs Einstein

Planck’s EQ, Equantum = hv, demonstrates mathematically the energy of a quantum is related to the frequency of the emitted radiation. Einstein went further by explaining that in addition to it’s wave-like characteristics, a beam of light can be thought of as a stream of energy called photons.

Continuous electromagnetic spectra vs atomic emission spectra

The atomic emission spectrum is the set of frequencies of the electromagnetic waves emitted by atoms of the element, unlike the continuous electromagnetic spectrum, it’s several individual lines of color corresponding to the frequencies of radiation emitted by the atoms.

Emission Spectrum

when atoms absorb energy and try to return to their stable state by releasing the energy. If the light emitted is passed through a glass prism an emission spectrum is produced; distinct wavelengths only with no transitions

Particle model of light

it describes why heated objects emit certain frequencies of light at a given temperature and why some metals emit electrons when light of a specific frequency shines on them.

Einstein

he proposed that light has a wavelike particle like properties, extending Planck’s idea of quantized energy by calculating that a photon’s energy depends on it's frequency. He said the energy of a photon must have a certain threshold value to cause ejection of photoelectron from metal’s surface, thus explaining the photoelectric effect.

Radio waves

of electromag radiation, has the longest wavelength

Gamma ray

of electromag radiation has the highest frequency and greatest energy

electron configuration, represented by orbital diagrams as well

arrangement of electrons in an atom

in orbital diagrams, the box represents the orbital where there should be two electrons with opposite spins

aufbau principle

each electron occupies the lowest energy avaliable

pauli exclusion principle

a maximum of two electrons can occupy a single atomic orbital, but only if they have opposite spins

hund’s rule

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

valence electron

electrons in antom’s outermost orbitals usually highest principal energy level

electron dot structure

consists of element symbol