EL3 - Shells, Sub-Shells and Orbitals

Question 1

What is the principal quantum number?

Answer 1

Shell

Given as n (i.e. 1,2,3 etc. the number before the letter…)

The higher the value, the higher the energy

Question 2

What are shell divided into?

Answer 2

Sub-shells

Labelled s, p, d, and f

Question 3

What is each sub-shell divided into?

What are its properties?

Answer 3

Atomic orbitals

Each can hold max of 2 electrons

These electrons must have opposite (or paired) spinds

Represented by boxes. Arrows drawn in them represent electrons

Question 4

How many orbitals does the s subshell contain?

Answer 4

1 s-orbital

Question 5

Summarise the way in which electrons are organised in atoms, starting with the largest grouping.

(3)

Answer 5

Shell/PQN

Sub-shells

Atomic orbitals

Question 6

What are the different shapes of the p orbital

Answer 6

px-orbital

py-orbital

pz-orbital

The three orbitals are aligned along perpendicular axis

Question 7

How many orbitals does the p subshell have?

Answer 7

3

Question 8

How many orbitals does the d subshell have?

Answer 8

5

Question 9

How many orbitals does the f subshell have?

Answer 9

7

Question 10

What are the rules that determine the distribution of electrons in atomic orbitals?

Answer 10

• The orbitals are filled in order of increasing energy
• Where there is more than one orbital at the same energy, the orbitals are first occupied by a single electron. When each orbital is singly occupied, the electrons pair up in the orbitals
• Electrons in singly occupied orbitals have parallel spins
• Electrons in doubly occupied orbitals have opposite (paired) spins

Question 11

What are the 2 ways of representing electron distribution?

Answer 11

By writing out the electronic configuration in full
e.g. 1s22s22p5

By drawing the electronic configuration in boxes…

Question 12

What is the shape of the s-orbital?

Answer 12

Spherical

Question 13

What subshells are in each shell?

Answer 13

The n=1 shell has only an s-subshell.

The n=2 shell has the s and p subshells.

The n=3 shell has the s, p and d subshells.

The n=4 shell has the s, p, d and f subshells.

Question 14

How many electrons are held in different types of subshells?

Answer 14

The n=1 shell can hold two electrons in the s subshell.

The n=2 shell can hold two electrons in the s subshell and six electrons in the p subshell.
(8 in total)

The n=3 shell can hold two electrons in the s subshell, six electrons in the p subshell and 10 electrons in the d subshell.
(18 in total)

The n=4 shell can hold two electrons in the s subshell, six electrons in the p subshell, 10 electrons in the d subshell and 14 electrons in the f subshell.
(32 in total)

Question 15

The energy of a subshell is not fixed, but falls as …

Answer 15

the charge on the nucleus increases from one element to the next in the periodic table.

Question 16

After nickel, the 3d subshell has lower energy than…

Because…

Answer 16

4s

there is an overlap in energy between the n=3 and n=4 shells

Question 17

An s subshell always contains
__ s-orbital.

A p subshell always contains
__ p-orbitals.

A d subshell always contains
__ d-orbitals.

An f subshell always contains
__ f-orbitals

Answer 17

s - 1

p - 3

d - 5

f - 7

Question 18

How many electrons can each atomic orbital hold at maximum?

Answer 18

2

Question 19

NOTE:

Every electron spins at the same rate in either a clockwise (^) or anticlockwise (v) direction.

Electrons can only occupy the same orbital if…

Answer 19

They have opposite spins.

They can be written as
an up arrow and down arrow in a box.

The box represents the atomic orbital and the arrows represent the electrons.

Question 20

What four pieces of information are needed when describing an electron?

Answer 20

The electron shell it’s in

Its subshell

Its orbital within the subshell

Its spin

Question 21

The orbitals are filled up in order of…

Answer 21

increasing energy.

Question 22

In terms of filling up atomic orbitals, what happens when there is more than one orbital with the same energy?

Why?

Answer 22

These orbitals are first occupied singly by electrons.

This keeps electrons in an atom as far apart as possible.

Only when every orbital is singly occupied do the electrons pair up in orbitals.

For the lowest energy arrangement, electrons in singly occupied orbitals have parallel spins.

Question 23

NOTE:
Aufbau Diagram (triangle w arrows)

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f (5g)
6s 6p 6d (6f 6g 6h)
7s 7p (7d  7f 7g  7h 7i)

s holds up to 2
p holds up to 6
d holds up to 10
f holds up to 14

Answer 23

NOTE:
Aufbau Diagram (triangle w arrows)

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f (5g)
6s 6p 6d (6f 6g 6h)
7s 7p (7d  7f 7g  7h 7i)

s holds up to 2
p holds up to 6
d holds up to 10
f holds up to 14

Question 24

1s^2

What does the
1
s
^2
refer to?

Answer 24

1s^2

The electron is in the first electron shell.

The electrons are in an s type orbital.

There are two electrons in this orbital.