2.2.1 & 2.2.2: Group 2 Flashcards
Ionisation energy…
why
decreases down group 2
The outer electrons are further away from the nucleus so have less attraction to the nucleus
Atomic radius…
why
Increases down group 2
each electron is a shell further away
Melting point…
why
Decreases down group 2
Ion cores have larger radii
free electrons have less attraction to the nucleus
and weaker bonding
Melting point trend anomaly
what and why
Magnesium
has a lower mp. as it has a different crystal structure
Reactions with water…
Group 2 metals react with water to form metal hydroxides
Reactivity…
why
Increases down group 2
as elements have lower ionisation energies
Reactivity trend anomaly
Beryllium
if it lost 2 e-s it would be tiny and high charge density so unstable and therefore it doesn’t react with water
Solubility of salts…
hydroxides
+ example
increase down group 2
Mg(OH)2 is very soluble ‘sparingly soluble’
Solubility of salts…
sulphates
+ example
Decreases down group 2
BaSO4 is completely insoluble
Example of use of group 2 element in healthcare
Barium meals
Barium meals
BaSO4
insouble and reflects x-rays
makes the soft tissue show up on x-rays
coats soft tissue
Wet scrubbing
The process of removing SO2 from flue gases
Compounds used in wet scrubbing
2
Calcium carbonate
Calcium oxide
sprayed onto the gases
make = CaSO3 calcium sulphite
Main uses of group 2 elements
4
In healthcare
Wet scrubbing
As bases to neutralise acids
Titanium extraction
Use of group 2 elements as bases to neutralise acids
Calcium hydroxide and Magnesium hydroxide
Ca(OH)2 in agriculture to neutralise acidic soils
Mg(OH)2 in indigestion tablets that neutralise excess stomach acid
