Group 2 the alkaline earth metals

Question 1

what charge ions does Group 2 metals form

Answer 1

2+

• all their electron configurations end in s2

Question 2

Does ionisation energy increase or decrease DOWN group 2

Answer 2

DECREASES

• atomic radius increases
• increased shielding so weaker attraction between nucleus and outer shell electrons, as they are far away
• making it easier to remove the outer electron, as less energy is required

Question 3

if we have an increase in proton number down group 2,

then why doesn’t ionisation energy increase

Answer 3

This is because SHIELDING effect OVERRIDES an increase in positive charge

Question 4

Does melting point increase or decrease down group 2
AND WHY

what element is an exception in the Group 2 MP trend

Answer 4

DECREASE

1) size of metal ions increases but the number of delocalised electrons remains the same
2) larger ions means the distance between delocalised electrons and ions is GREATER, so weaker electrostatic forces of attraction between them, less energy required to break bonds, so LOWER MP
- Mg because it has a different strucutre compared to other group 2 metals

Question 5

what do group 2 metals form when reacting with water

and what is the reactivity trend with water down the group

Answer 5

Base( alkaline substance)

they form metal hydroxides and hydrogen

EG. Sr+ 2H2O-> Sr(OH)2 +H2

• reactivity increases with water down the group:
  beacause
• larger atom down group
• weaker attraction and more shielding
• more reactive

Question 6

what does magnesium react more vigorously with

water or steam

Answer 6

Steam

producing MgO instead of Mg(OH)2

Question 7

group 2 hydroxides solubility increase OR decrease down the group??

Answer 7

INCREASE
Group 2 hydroxides solubility increase

THEY NEED MO WOTAH

good way to remember: Group 2 hydroxides have a single (1-) negative charge

so become MORE soluble down the group

Question 8

group 2 sulfates solubility increase OR decrease down the group?

Answer 8

DECREASE

good way to remember: Group 2 sulfates have a double negative charge(2-)
so become LESS soluble down the group

Question 9

Test for sulfates

Answer 9

USE Barium Chloride

1) Add HCl to remove any carbonates to prevent giving a false result when being precipitated out
2) Add barium chloride
- White precipitate formed- which is the insoluble BaSO4

Question 10

what can group 2 compounds be used for

Answer 10

to neutralise acids

acidic soil- ca(OH)2 neutralises acid in the soli

Antacids- Neutralises excess stomach acid

Question 11

what is Barium meal

Answer 11

Barium sulfate

it is insoluble so desn’t get absorbed in the blood
but it is TOXIC