S Block

Question 1

What groups are in the s block?

Answer 1

1 and 2

Question 2

What are the main characteristics of s block elements?

Answer 2

Metallic character
Low electronegativity
Basic oxides, hydroxides
Ionic bond with fixed oxidation states
Characteristic flame colours
Weak tendency to form complexes

Question 3

Explain the metallic character.

Answer 3

High tendency to lose electrons to form positive ions.
Metallic character increases down both groups.

Question 4

Explain electronegativity.

Answer 4

Low nuclear attraction for outer electrons.
High electropositive.

Question 5

What s block elements form basic oxides?

Answer 5

All

Question 6

What s block elements form peroxides?

Answer 6

Na, K, Rb, Cs, Ba

Question 7

What s block elements form super oxides?

Answer 7

K, Rb, Cs, Ba

Question 8

What are the trends in group 1 hydroxides?

Answer 8

All are soluble, base strength increases down group.

Question 9

What are the trends in group 2 hydroxides?

Answer 9

Solubility increases, amphoteric to basic, base strength increases down group.

Question 10

What are the flame colours of the group one elements?

Answer 10

Li = deep red
Na = yellow
K = lilac
Rb = bluish red
Cs = blue

Question 11

What are the flame colours of the group two elements?

Answer 11

Ca = brick red
Sr = blood red
Ba = apple green

Question 12

Why do s block elements have a weak tendency to form complexes?

Answer 12

No low energy vacant orbitals available for bonding with lone pairs of surrounding ligands

Question 13

How does atomic radii change?

Answer 13

Increases down the group

Question 14

How does ionisation energy change?

Answer 14

Decreases down the group

Question 15

Explain ionisation enthalpies of group 1 elements.

Answer 15

Low first IE as well shielded from nucleus by inner shells.
Removal of second electron harder due to it being in the inner shell.
As atomic radius increases the outer electron is further away from the well shielded nucleus.

Question 16

Explain ionisation enthalpies in group 2.

Answer 16

Low first and second IE.
Removal of the third electron harder as from inner shell.
IE of group 2 generally higher than group 1.

Question 17

Describe the trends of hydration enthalpy in the s block.

Answer 17

Decreases down group, as ions get bigger, charge density decreases, electrostatic attraction between ions and water molecules gets smaller.
Group 2 > 1, doubly charged and smaller.

Question 18

How does melting point change in the s block elements?

Answer 18

Decreases down the group, exception of sharp drop of Mg below Ca.

Question 19

Explain s block reactions with oxygen.

Answer 19

Strong reducing agents, reducing power increases down both groups. React readily with O.
Be and Mg to be stored under paraffin.

Question 20

What s block elements react with hydrogen?

Answer 20

All bar Be.

Question 21

What are the uses of sodium carbonate?

Answer 21

Manufacture of glass
Water softening
Paper industry

Question 22

What are the uses of sodium hydrocarbonate?

Answer 22

Baking powder
Soft drink

Question 23

What are the uses of sodium hydroxide?

Answer 23

Soaps, dyes, paper, drugs
Rayon

Question 24

What are the uses of magnesium hydroxide?

Answer 24

Milk of magnesium

Question 25

What are the uses of calcium hydroxide?

Answer 25

Neutralize acids in waste water treatment..