3.1.1 electronic configuration

Question 1

how many sub-shells are there in a shell?

Answer 1

4; s, p, d, f sub-shells

Question 2

how many electrons can each orbital hold?

Answer 2

2 electrons; opposite spin

Question 3

state the number of orbitals and electrons in each sub-shell

Answer 3

s = 1 orbital; 2 electrons
p = 3 orbitals; 6 electrons
d = 5 orbitals; 10 electrons
f = 7 orbitals; 14 electrons

Question 4

state which sub-shells are present in each shell

Answer 4

1 = 1s
2 = 2s, 2p
3 = 3s, 3p, 3d
4 = 4s, 4p, 4d, 4f

Question 5

explain the ‘bus seat’/ Aufbau theory

Answer 5

electrons have opposite spins + repel each ofther due to 1- charge
each orbital fills with 1 e- FIRST before filling w/ 2nd one
always fill from lowest energy shell first

Question 6

what is the exception when filling energy shells from lowest to highest?

Answer 6

the 4s sub-shell must be filled before the 3d sub-shell
4s has slightly lower energy

Question 7

describe how ions are formed?

Answer 7

electrons are added/removed from atom
from highest energy level that’s occupied by an e-

Question 8

explain why some elements do not follow the exception to fill 4s sub-shell first

Answer 8

COPPER + CHROMIUM
have 1 e- in 4s
donate e- from 4s sub-shell to 3d
allowing 3d to be partially or completely full
makes elements more stable
form ions = remove/add from 4s BEFORE 3d bc it’s slightly lowerw

Question 9

what does it mean when 2 atoms/ions are isoelectronic

Answer 9

they have the same electronic configuration
e.g K+ and Cl -