2.2 Electrons in atoms

Question 1

What does n stand for?

Answer 1

It represents the energy levels

Question 2

What are energy levels split into?

Answer 2

They are split into 4 sublevels (s, p,d,f)

Question 3

What does 2s mean?

Answer 3

The 2 means the second main energy level and s is the atomic orbital

Question 4

What is an atomic orbital?

Answer 4

Represents region of space where there is high possibility of finding an electron

Question 5

What shape are s orbitals?

Answer 5

They are spherical

Question 6

How many p orbitals are there and what shape are they?

Answer 6

There are 3: Px, Py, Pz and they are dumbbell shaped

Question 7

How many electrons can each sublevel hold?

Answer 7

S= 2
P= 6
D= 10
F= 14

Question 8

How many orbitals does n=2 have?

Answer 8

4 (2s and 3 2p orbitals)

Question 9

What is the Pauli exclusion principle?

Answer 9

States that two electrons cannot have the same quantum number i.e. two electrons can only occupy the same orbital if they have opposite spin

Question 10

What is Heisenberg’s uncertainty principle?

Answer 10

States that it isn’t possible to know the exact position and momentum of an electron. Probability of knowing is usually 95%

Question 11

What is Aufbau’s principle?

Answer 11

• 1st sub level has lowest energy so it is filled first
• S orbitals are filled before P orbitals and so on
• All 1s orbitals, 2s, 2p orbitals etc. are of equal energy (degenerate)
• There is overlap between 3d and 4s orbitals so 4s orbitals fill first as it has lower energy

Question 12

What is electron configuration of Neon?

Answer 12

1s2 2s2 2p6

Question 13

What is electron configuration of Calcium?

Answer 13

1s2 2s2 2p6 3s2 3p6 4s2

Question 14

Exceptions: Electron configuration of Chromium

Answer 14

1s2 2s2 2p6 3s2 3p6 4s1 3d5

Question 15

Exceptions: Electron configuration of Copper

Answer 15

1s1 2s2 2p6 3s2 3p6 4s1 3d10

Question 16

How would you draw an orbital diagram for carbon?

Answer 16

1s2 will have 2 arrows in one box
2s2 will have 2 arrows in one box
2p6 will have three boxes where 2 are filled with one arrow and one box is empty

Question 17

What is electron configuration for Ca2+?

Answer 17

1s2 2s2 2p6 3s2 3p6

Question 18

Which orbital loses electrons first: 4s or 3d?

Answer 18

4s will lose electrons first

Question 19

What is line spectra used for?

Answer 19

It is used to identify unknown elements

Question 20

Relationship between energy and wavelength/frequency

Answer 20

As wavelength decreases and frequency increases, energy increases

Question 21

What is wavelength?

Answer 21

Distance between two crests (metres). Represented by lamda

Question 22

What is frequency?

Answer 22

Number of waves that pass a point in one second (Hz)

Question 23

How do you calculate speed of light?

Answer 23

Wavelength x frequency

Question 24

Compare frequency and wavelength of UV and infrared

Answer 24

UV has higher frequency and shorter wavelength while infrared has shorter frequency and longer wavelength.

Question 25

Which has higher energy: UV or infrared?

Answer 25

UV as it has higher frequency

Question 26

What is the continuous spectrum?

Answer 26

It shows all wavelengths or frequencies of visible light

Question 27

Absorption line spectrum

Answer 27

Shows wavelengths that are missing in the form of black lines/stripes

Question 28

Emission line spectrum

Answer 28

Shows difference in energy levels through coloured lines

Question 29

What happens when high voltage is passed through a gas?

Answer 29

Electrons become excited and transition to higher energy levels by absorbing energy (ALS). When they fall back, there is emission of energy (ELS)

Question 30

What is the equation for energy using frequency?

Answer 30

E= hf where h is Planck's constant and f is frequency

Question 31

What is Planck's constant?

Answer 31

6.64 x 10^34 Js

Question 32

Do energy levels get closer or farther as they increase?

Answer 32

Closer

Question 33

What is visible emission line spectrum?

Answer 33

They are a set of 4 lines that converge at high frequency

Question 34

What does it represent when electrons move back to n=1 (ground state)?

Answer 34

UV radiation

Question 35

Which n do electrons return to in visible light and infrared?

Answer 35

n=2 and n=3 respectively