2.2 Group 2 Flashcards Preview

AQA A-Level Inorganic Chemistry > 2.2 Group 2 > Flashcards

Flashcards in 2.2 Group 2 Deck (20)
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What is the trend of atomic radius? Why?

Atomic radius increases

Larger number of principal energy levels - more electrons


What is the trend of first ionisation energy? Why?


Larger atomic radius therefore the outer electron is further away from the nucleus
Electrostatic force of attraction is weaker
The electron is more easily lost


What is the general trend of melting points? Why?


The charge density decreases which decreases the strength of the metallic bonds


What is significant about the melting points of group 2?

Magnesium is an anomaly but we just ignore it


What is the general trend of electronegativity of group 2? Why?

Electronegativity decreases down the group

Atomic radius increases
Therefore the bonding pair is further away from the nucleus


Is electronegativity relevant for group 2? Why?


Group 2 are metals and don’t covalently bond


What is the general trend in solubility of group 2 hydroxides?

Solubility increases down the group

Mg(OH)2 - insoluble (white ppt)
Ca(OH)2 - slightly soluble (white ppt)
Sr(OH)2 - soluble (nvc)
Ba(OH)2 - soluble (nvc)


What is the general trend in solubility of group 2 sulfates?

Solubility decreases down the group

MgSO4 - soluble (nvc)
CaSO4- slightly soluble (nvc)
SrSO4 - insoluble (white ppt)
BaSO4 - insoluble (white ppt)


What are some uses of Mg(OH)2 - magnesium hydroxide?

Indigestion relief
Neutralising acidic waste water
Raising soil pH


What is special about Mg(OH)2 that is different from normal hydroxide properties?

Hydroxides are corrosive but

Mg(OH)2 is safe to ingest for humans as it is poorly soluble

Therefore a concentration of OH- isn’t present


What are some uses of BaSO4 - Barium sulfate?

Barium meal - contrasting agent in X-rays (good at absorbing them)

It is toxic but safe to ingest as it is insoluble


When writing a simple ionic equation what do we use?

Strips down to the ions/molecules we care about ignoring the other stuff


What are some factors of group 2 metals reacting with liquid water?

Produces a metal hydroxide and hydrogen gas


What are some factors of group 2 metals reacting with gaseous water (steam)?

Produces a metal oxide and hydrogen gas

Steam = over 100 degrees


What is the general trend of reactivity of group 2? Why?

Reactivity increases down group 2

The outer two electrons are further from the nucleus (more principal energy levels) therefore are less strongly held and easier to lose (weaker ESF)


What do group 2 have as a property?

They are reducing agents

(They themselves oxidise)


How is titanium extracted?

1) TiO2 + 2C + 2Cl -> TiCl4 + 2CO

2)TiCl4 + 2Mg -> Ti + 4MgCl2

Magnesium or sodium can be used
Done at very high temperatures and using an argon atmosphere


What are disadvantages to the extraction of titanium?

Expensive due to

High temperatures
Argon atmosphere
Cl made by electrolysis (not cheap)
CO waste has to be managed


How do you test for a sulfate ion?

Add HCl
Then added BaCl2

If sulfate ions are present BaSO4 is produced
As BaSO4 is insoluble a white ppt is shown


Why is a sample acidified first in the test for sulfate ions?

As carbonate ions also produce a white ppt with BaCl solution

So the acid reacts with CO3 ions to prevent a false positive result