Topic 2.2: Electron configuration

Question 1

Electromagnetic spectrum

Answer 1

Spectrum of wavelengths that comprise the various types of electromagnetic radiation

Question 2

Relation of energy, wavelength, and frequency

Answer 2

a) Energy is inversely proportional to wavelength

b) Energy is proportional to frequency

Question 3

Electromagnetic radiation

Answer 3

A form of energy that propagates through space at the speed of light as photons

Question 4

Continuous spectrum

Answer 4

Radiation that spreads all frequencies / wavelengths of light present

Question 5

Line spectrum

Answer 5

Radiation that emits only certain frequencies/wavelengths of light present

Question 6

Line spectrum and element

Answer 6

Each element has its own characteristic line spectrum which can be used to identify the element

Question 7

Quantization

Answer 7

Electromagnetic radiation comes in discrete parcels.

Question 8

Energy equation

Answer 8

E = hv = hc / A

Question 9

Electron transition in energy levels

Answer 9

a) Electron can move to a higher energy level by absorption of a photon
b) Electron can move from an excited state to a lower energy level by emitting a photon

Question 10

Hydrogen line spectrum

Answer 10

Discrete lines which converge at higher energies and form a continuum

Question 11

Ionization in line spectrum

Answer 11

Beyond the convergence limit the electron can have any energy and is not longer in the atom.

Question 12

Series of lines in the hydrogen line emission spectrum

Answer 12

a) Balmer series
b) Lyman series
c) Paschen series

Question 13

Balmer series

Answer 13

a) Visible region

b) Electronic transitions from upper energy levels back down to the n = 2 energy level.

Question 14

Lyman series

Answer 14

a) UV region

b) Electronic transitions from upper energy levels back down to the n = 1 energy level.

Question 15

Paschen series

Answer 15

a) IR region

b) Electronic transitions from upper energy levels back down to the n = 3 energy level.

Question 16

Emission spectrum

Answer 16

Spectrum of frequencies of ER emitted due to an atom making a transition from a high energy to a lower energy state.

Question 17

How is an emission spectrum formed?

Answer 17

a) Passing an electric discharge through a gas causes an electron to be promoted to a higher energy level (shell).
b) The electron is unstable in this higher level and will fall to a lower energy level, giving out extra energy in the form of a photon light

Question 18

Electron shell (n = 1,2,3)

Answer 18

a) Main energy level

b) Can hold a maximum number of 2n^2 e-

Question 19

Subshells (s < p < d < f)

Answer 19

Each subshell has a particular number of orbitals

Question 20

Atomic orbital

Answer 20

a) Region in space where there is a high probability of finding an electrom
b) Can hold a maximum of two electrons of opposite sign

Question 21

Electron arrangement

Answer 21

Shows the number of electrons in each shell or orbit

Question 22

Aurfbau principle

Answer 22

Electrons fill sub-levels from the lowest energy level upwards

Question 23

Reasons for removing electron from 4s before 3d levels of 3d-block elements

Answer 23

3d orbitals are more compact than the 4s orbitals and hence electrons entering the 3d orbitals will experience a much greater mutual repulsion.

Question 24

Pauli exclusion principle

Answer 24

Any orbital can hold a maximum of two electrons, having opposite spin

Question 25

Hund’s rule of maximum multiplicity

Answer 25

When filling degenerate orbitals, electrons fill all the orbitals singly before occupying them in pairs to minimize repulsion

Question 26

Reason for exceptions in Cr and Cu

Answer 26

Having the maximum number of electron spins the same within a set of degenerate orbitals gives a lower energy (more stable) situation