Chemistry TEST UNIT 1

How are emssion line spectra produced

produced when electrons transition from higher to lower energy levels, emitting energy in the process.

electron from n=3 to n=2

red

electron from n=4 to n=2

green

n=5 to n=2

blue

n=6 to n=2

purple

electron transition to n=1

UV radiation (highest energy transitions)

e- transition to n=2

visible light

e- to n=3

infared radiation

different spectrums and differences

emission spectrum- coloured lines on black background, shows the specific wavelengths (or frequencies) of light emitted

absorption spectrum- black lines on coloured backgrounds

continuous spectrum- shows all wavelengths / frequencies of visible light

absorption and emission

absorb- lower to higher energy level

emission- higher to lower energy level

Aufbau principle

when adding electrons to an atom, the lower energy orbitals must be filled first.

Pauli exclusion principle

an atomic orbital can only hold two electrons and they must have opposite spins.

Hund’s rule

when we have degenerate orbitals (orbitals of the same energy) then each orbital is filled with a single electron before being doubly occupied.

Order of sublevels filled

exceptions to the Aufbau principle

Cr- 4s1 3d5

Cu - 4s1 3d10

Heterogeneous mixture

non-uniform

visible phases or boundaries such as those that can be seen between the 2 things

Homogeneous

Homogeneous mixtures do not have visible phases or boundaries. They have a uniform composition meaning that the components of the mixture are equally distributed and in the same state.

Solvation

the separation of a heterogeneous mixture of two solids based on differences in 

solubility

the solvent molecules surround the soluble molecules and 

dissolve the solid into a solution. The insoluble solid can now be separated by filtration. The soluble substance can be separated from the solution by evaporation.

recrystalisation

remove impurities that are mixed in with a solid.

Hot solvent is added (minimum amount for dissolving) to impure solid

When crystals are formed, they are left to cool, which decreases solubility (in the solution, which impurities are in)

Filtration then done to obtain pure crystals.

What is the electromagnetic spectrum?

The electromagnetic spectrum is a range of frequencies that covers all electromagnetic radiation and their respective wavelengths and energy.

Define the term ionisation energy

Ionisation energy is the maximum amount of energy an electron can reach, corresponding to the energy required for the electron to escape the atom.

Define the term frequency

Frequency is the number of waves per second