S1.3 Electronic configurations

How are frequency(f), energy and wavelength(λ) related

Wavelength is inversely related with frequency n energy

Long wavelength→Low frequency n energy

Short wavelength→High frequency n energy

Formula of speed of light

c=fλ

Emission spectrum levels

Always from higher energy level to lower as electron loses energy by emitting photon(From outer shells to inner)

Infrared: n=∞ → n=3

Visible light: n=∞ → n=2

Ultraviolet: n=∞ → n=3

What happens when electrons move up energy levels?

They absorb light

What happens when electrons move down energy levels?

They emit light

How does mass spectrometer work?

• Chemical sample placed into device and It’s heated up till it’s vaporized

• Electron gun emits of beam of high energy electrons through sample

• This causes atoms in sample to lose some electrons and become positively charged

• Positively charged ions pass through electric field(accelerates movement of cations)

• They pass through magnet that deflects them and changes their direction

• Atoms with lowest mass and highest charge are deflected more

• Atoms pass through detector to register location of atoms and determine mass and charge

Mathematical relationship between number of electrons and principal energy level

Energy level: n(n=3)

Number of electrons: 2n²(2×9=18)

Increasing energy order of subshells

s<p<d<f

What is the shape of s orbital

Spherical

Size increases with increasing shell number

What is the shape of p orbital

Dumbbell-shape

Each shell(except n=1) has 3 p orbitals(px, py, pz)

They lie on the x, y, z axes respectively

What are limitations of the Bohr’s model?

1. Assumes electrons have fixed positions

2. Assumes all energy levels are spherical

3. Only accurately explains hydrogen spectrum(fails for atoms w <1 electron)

What is the limit of convergence?

The point where lines in an emission spectrum merge into continuous spectrum

What does limit of convergence represent?

Energy required to remove an electron from an atom (ionization energy)

Conversion of nm to m

x 10^-9

Energy formula

E=hf

h: planck’s constant

f: frequency

True or false: E=hf calculates energy of one mole of electrons

False

It calculates energy of one photon

Always multiply by avogadro’s constant to find ionisation energy(per mole)

Note to remember

Convert wavelength from nm to m(x 10^-9) when calculating frequency

Why is it easier to removed a paired electron from an orbital than a single electron

Spin pair repulsion: the 2 electrons repel each other, making it easier for one of them to leave

What do large jumps and small jumps in IE show

Large→change in shell

Small→changes within subshell