S1.3 Electronic configuration

Question 1

What are emission spectra produced by?

Answer 1

Atoms emitting photons when electrons in excited states return to lower energy levels

Question 2

Order of the EM spectrum in increasing frequency and energy

Answer 2

• Radiowave
• Microwave
• Infrared
• Visible light
• Ultraviolet
• X-rays
• Gamma rays

Question 3

What does a continuous spectrum consist of?

Answer 3

All colours merging into each other

Question 4

What does the line emission spectrum of hydrogen provide evidence for?

Answer 4

The existence of discrete energy levels which converge at higher energies

Question 5

What light is emitted from an electron falling back to main energy level 1?

Answer 5

UV

Question 6

What light is emitted from an electron falling back to main energy level 2?

Answer 6

Visible light

Question 7

What light is emitted from an electron falling back to main energy level 3`?

Answer 7

Infrared

Question 8

What light is emitted from an electron falling back to main energy level 4?

Answer 8

Infrared

Question 9

What light is emitted from an electron falling back to main energy level 5?

Answer 9

Infrared

Question 10

What is the maximum number of electrons the a main energy level n can hold?

Answer 10

2n²

Question 11

Order of the sublevels

Answer 11

s<p<d<f

Question 12

What does each orbital have?

Answer 12

A defined energy state for a given electronic configuration and chemical environment, and can hold up to two electrons of opposite spin

Question 13

What do sublevels contain?

Answer 13

A fixed number of orbitals

Question 14

Orbital

Answer 14

Region of space where there is a high probability of finding an electron

Question 15

The Aufbau Principle

Answer 15

Electrons fill orbitals from the lowest energy orbital upwards as this gives the lowest possible potential energy

Question 16

Full electronic configuration of Cr

Answer 16

1s²2s²2p⁶3s²3p⁶4s¹3d⁵

Question 17

Full electronic configuration of Cu

Answer 17

1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰

Question 18

Condensed electronic configuration of Cr

Answer 18

[Ar] 4s¹3d⁵

Question 19

Condensed electronic configuration of Cu

Answer 19

[Ar] 4s¹3d¹⁰

Question 20

Pauli exclusion principle

Answer 20

The maximum number of electrons in an orbital is two. If there are two electrons in an orbital they must have opposite spins

Question 21

Hund’s rule

Answer 21

Electrons fill orbitals of the same energy level (degenerate orbitals) so as to give the maximum number of electrons with parallel spins

Question 22

What does the convergence limit at higher frequencies correspond to in an emission spectrum?

Answer 22

Ionization

Question 23

E

Answer 23

hf

Question 24

Planck constant (h)

Answer 24

6.63*10^-34

Question 25

c

Answer 25

fλ

Question 26

Why do successive ionisation energies of K increase?

Answer 26

- The outermost electron is shielded from the full attractive force of the nucleus by the electrons between it and the nucleus. Therefore it is relatively easy to remove. - The next electron is considerably more difficult to remove, since it is from a new shell, therefore it is: - Closer to the nucleus - Only shielded by electrons in lower shells since electron in the same shell do not shield each other very well - The removal of the next seven electrons gets successively more difficult without big jumps since they are being removed from the same shell and there is no significant increase in shielding

Question 27

Why is second ionisation energy always higher than the first?

Answer 27

- The electron is being removed from a positively charged ion so experiences stronger electrostatic attraction - Decrease in electron-electron repulsion

Question 28

Why is there a dip in IE across period 2 between N and O?

Answer 28

Oxygen has a lower 1st IE than nitrogen due to greater electron-electron repulsion when removing an electron from the antiparallel pair in the same orbital

Question 29

Why is there a dip in IE across period 2 between Be and B?

Answer 29

Boron has a lower 1st IE than beryllium because the outer electron in boron is removed from a 2p orbital compared to only a 2s orbital in beryllium

Question 30

What is the general trend in IE across a period?

Answer 30

- Ionisation energy increases from left to right - The nuclear charge increases - Electrons added to the same shell have no significant increase in shielding - Therefore, the force required to remove an electron increases

Question 31

What does ionisation energy do down a group?

Answer 31

Decreases because as more energy levels are added the outer electron becomes further from the nucleus and has higher energy so experiences weaker attraction to the nucleus

Question 32

What is the exception to the "first in last out rule"?

Answer 32

The 4s electrons are always removed before the 3d electrons

Question 33

Why does the emission spectrum arise?

Answer 33

When an electron is promoted to a higher energy level it is unstable so it will return to a lower energy level, emitting a photon which creates a line on the spectrum

Question 34

What is the general rule for removing electrons?

Answer 34

First in, last out