ATOMIC STRUCTURE PERIODIC TABLE 2

Question 1

What letter used to represent

shell number?

Answer 1

n

Question 2

From which shell onwards is S

orbital present?

Answer 2

n = 1

Question 3

From which shell onwards is

P-orbital present?

Answer 3

n = 2

Question 4

From which shell onwards is

D-orbital present?

Answer 4

n = 3

Question 5

From which shell onwards is

F-orbital present?

Answer 5

n = 4

Question 6

What are the rules by which
electrons are arranged in the
shell?

Answer 6

● Electrons are added one at a time
● The lowest available energy level is filled first
● Each energy level must be filled before the next one can fill
● Each orbital is filled singly before pairing
● 4s is filled before 3d

Question 7

Why does 4s orbital fill before

3d orbital?

Answer 7

4s orbital has a lower energy than 3d

before it is filled

Question 8

What is the electron

configuration of krypton

Answer 8

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

Question 9

How can the electron
configuration be written in
short?

Answer 9

The noble gas before the element is
used to abbreviate

Li → 1s2 2s1
Li → [He] 2s1

Question 10

How are the elements

arranged in a periodic table?

Answer 10

Group number = number of electrons in

the outer shell

Question 11

What is a period on a periodic

table?

Answer 11

The horizontal rows

Question 12

What is a group on a periodic

table?

Answer 12

The vertical columns

Question 13

How is the group number
related to the number of
electrons?

Answer 13

They are arranged in the order of

increasing atomic numbers

Question 14

Does the group number
indicate horizontal or vertical
columns in the periodic table?

Answer 14

Vertical column

Question 15

What is meant by periodicity?

Answer 15

The repeating trends in chemical and

physical properties

Question 16

What change happens across

each period?

Answer 16

Elements change from metals to

non-metals

Question 17

Define first ionisation energy.

Answer 17

The energy required to remove a mole of electrons from a mole of gaseous atoms
to form one mole of gaseous 1+ ions
under standard conditions

Question 18

Write an equation for the first
ionisation energy of
magnesium.

Answer 18

Mg(g) → Mg+(g) + e-

Question 19

What are the factors that affect

ionisation energy?

Answer 19

● Atomic radius
● Nuclear charge
● Electron shielding or screening

Question 20

Explain the trend on this graph
First ionisation energy (kJmol) AGAINST Element

16| x
14|
12| x
10| x x
8 | x x
6 | x
4 | x
2 |
0 |_____________________________
Na Mg Al Si P S Cl Ar

Answer 20

● First Ionisation energy increases across period 3 because of:
○ Increased nuclear charge
○ Decreased atomic radius
○ Same electron shielding
● This means more energy is needed to remove the first electron.
● Dips at Al because the outer electron is in a 3p orbital, higher energy than 3s orbital → less energy needed to remove the electron
● Dips at S because one 3p orbital contains two electrons → repulsion between paired electrons → less energy needed to remove one