module 2 - electrons, bonding and structure

Question 1

how do you represent shell number at a-level?

Answer 1

n = 1
n = 2
n = 3
n = 4

Question 2

how many electrons are in the 1st shell?

Answer 2

2

Question 3

how many electrons are in the 2nd shell?

Answer 3

8

Question 4

how many electrons are in the 3rd shell?

Answer 4

18

Question 5

how many electrons are in the 4th shell?

Answer 5

32

Question 6

what are shells also known as?

Answer 6

energy levels

Question 7

what increases as shell number increases?

Answer 7

the energy increases

Question 8

what is the shell/energy level number called?

Answer 8

the principal quantum number n.

Question 9

what formula tells you the maximum number of electrons in a shell?

Answer 9

2n^2

Question 10

what are shells made up of?

Answer 10

atomic orbitals

Question 11

what’s an atomic orbital?

Answer 11

A region around the nucleus that can hold 2 electrons with opposite spins

Question 12

what shape is an s-orbital?

Answer 12

spherical

Question 13

what happens to the s-orbital with greater shell number?

Answer 13

the radius of its s-orbital is bigger

Question 14

in a p-orbital, what is the electron cloud within?

Answer 14

the shape of a dumb-bell

Question 15

how are p-orbitals positioned?

Answer 15

at right angles to each other

Question 16

How many p-orbitals does each shell form n=2 contain?

Answer 16

3

Question 17

what happens to the p-orbital with greater shell number?

Answer 17

the further it is from the nucleus

Question 18

how many d-orbitals does each shell from n=3 contain?

Answer 18

5

Question 19

how many f-orbitals does each shell from n=4 contain?

Answer 19

7

Question 20

what’s a sub-shell?

Answer 20

a group of orbitals of the same type within a shell

Question 21

why does the 4s sub-shell fill before the 3d sub-shell? what comes after it?

Answer 21

• because it’s at a lower energy level than the 3d sub-shell
• it goes: 3p, 4s, 3d, 4p etc…

Question 22

what property do electrons have? in which direction?

Answer 22

• spin

- up or down

Question 23

what must 2 electrons in an orbital have? why?

Answer 23

• opposite spins

- to counteract the repulsion between the negative charges of the 2 electrons

Question 24

within a sub-shell what is similar for all the orbitals?

Answer 24

they have the same energy

Question 25

when orbitals are filled up, what is the rule? why?

Answer 25

• 1 electron occupies each orbital before pairing up

- this prevents any repulsion between paired electrons

Question 26

what does the electron configuration of an atom show?

Answer 26

How sub-shells are occupied by electrons

Question 27

in 1s^2 which is the electron and which is the sub-shell?

Answer 27

• s = sub-shell

- 2 = electron

Question 28

what is the shorthand notation for lithium’s electron configuration

Answer 28

[He] 2s^1

Question 29

what do the blocks in the periodic table correspond to?

Answer 29

to their highest energy subshell

Question 30

when forming ions, which sub-shells lose or gain electron?

Answer 30

the highest energy ones

Question 31

why does the 4s sub-shell empty before the 3d when forming ions?

Answer 31

because once filled, the 3d energy level falls below the 4s energy level