Flashcards in 2.2 Group 2 Deck (20)
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?
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
Cl made by electrolysis (not cheap)
CO waste has to be managed
How do you test for a sulfate ion?
Then added BaCl2
If sulfate ions are present BaSO4 is produced
As BaSO4 is insoluble a white ppt is shown