Chemistry Unit 3

Specific heat capacity

Heat required to raise the temperature of 1 gram of a substance by 1 degree celsius

State function

Depends only on the current state of the system (independent of path taken)

Path function

Depends on how the system moves between states (different paths yield different values)

Standard enthalpy of formation

Enthalpy change when 1 mole of a substance is formed from its elements

Electromagnetic spectrum (low to high wavelength)

Gamma rays, X rays, UV, visible, infrared, microwaves, radio waves

Interference

When two or more waves overlap and combine

Constructive interference

Waves interact in phase, increasing the resulting amplitude and light intensity

Destructive interference

Waves interact out of phase, decreasing the resulting amplitude and light intensity

Diffraction

The bending and spreading of waves as they pass through an opening or around an obstacle

Blackbody radiation

EM radiation emitted by an object due to its temperature (as it gets hotter, it emits more radiation, glow can change color)

If incident frequency frequency is less than threshold frequency…

No electrons are ejected, regardless of intensity

If incident frequency is greater than threshold frequency…

Electrons are ejected

Increasing frequency for the photoelectric effect…

Increases KE

Increasing intensity for the photoelectric effect…

Increases the number of electrons emitted

Binding energy

Minimum energy required to remove an electron, excess energy becomes KE

Atomic emission spectrum

Every element has a unique emission spectrum, as it contains only specific, discrete wavelengths of light

Niels Bohr theory

Electrons move around the nucleius in specific orbits called energy levels with fixed radius and energy. Accurately predicts energy levels for one electtrom atoms and ions.

Emission

An electron loses energy and moves to a lower level, releasing a photon

de Brogile wavelength

Small particles of matter also exhibit wave-like properties, dependent and inversely proportional to mass and velocity

Heisenberg uncertainty principle

There is a fundamental limit to how precisely we can know both the position and momentum of an electron at the same time, applies mostly to smaller objects like electrons. More precise we know an electron’s position, the less precise we know its momentum and vice versa

n

Principal quantum number, determines probable distance of the electron from the nucleus and energy of an orbital

l

Angular momentum quantum number, describes the shape of the orbital where the electron is located

ml

Magnetic quantum number, describes the orientation of an orbital in space

ms

Spin quantum number, describes the orientation of an electron’s intrinsic angular momentum, called spin

Orbitals

Regions around the nucleus where an electron is most likely to be found, number of orbitals in a subshell is equal to the number of allowed ml values

s shape

spherical shape (l=0)

p shape

dumbbell shape with two lobes of electron density on opposite sides of nucleus (l=1)

d shape

four d orbitals have a cloverleaf shape with four lobes of electron density while the fifth d orbital has two lobes and a ring around its center (l=2)

f shape

orbitals shape becomes increasingly complex (l=3)

Electrons per orbital

Each orbital can hold a maximum of two electrons, which must have opposite signs