3. Waves and atomic spectrum of H

Question 1

Properties of waves

Answer 1

Question 2

Describe the electromagnetic spectrum

Answer 2

Question 3

What is interference?

Answer 3

Interference - the combination of two or more electromagnetic waveforms to form a wave in which displacement is reinforced or cancelled

In phase - waves up and down at the same point -> greater amplitude - constructive interferenc

Out of phase - highest and lowest points at the same time -> cancel out each other - destructive interference

Question 4

Which equation can be used to describe E of a photon?

Answer 4

E = hv

h - Planck’s constant

v (miu) - frequency of the light (in Hz/s)

Question 5

Explain photoelectric effect

Answer 5

Photoelectric effect - a phenomenon where electrically charged particles are released from a material when it absorbs electromagnetic radiation

But the e has to have a certain amount of E to be ejected

E = hv = φ + E_KE

φ - workfunction

E_KE - kinetic E of ejected e

Requirement for photoelectric effect: hv ≥ φ + E_KE

When ask for max wavelength that can eject an e from a material → min E required for photoelectric effect → E_KE = 0 => λ = hc / φ

Question 6

Explain atomic (line) spectrum

Answer 6

H gives line spectrum - certain E needed to kick an e out in an atom (photoelectric effect)

Question 7

Bohr’s quantised model equation for E

Answer 7

n - principal quantum number (1, 2, 3, 4…) - only it changes because everything else (all conditions) is a constant -> E can only be certain numbers

pi - constant

m_e - mass of e

e - charge of e

h - Planck’s constant

Question 8

How do quantum numbers related to atomic orbitals?

Answer 8

The circular orbits represent the only possible energies that an electron can have

Question 9

Explain quantisation

Answer 9

Quantisation - subdivision into small but measurable increments

Quantisation of E - certain E needed to transition between different E levels

But the E levels are not equally spaced - as the the level increases, the E keep getting more similar

Question 10

Explain the Rydberg equation

Answer 10

v (miu) - frequency

n - integer for energy levels

R_H - the Rydberg constant 3.29 x 10¹⁵ Hz (H for hydrogen, their element - other constant)

Question 11

What are the different emission series?

Answer 11