Group 2 Flashcards
What is trend in atomic radius for the group 2 elements?
As you go down the group, the atomic radius increases:
-Greater number of shells.
What is trend in first ionisation energies for the group 2 elements?
1st IE decreases down the group:
- Larger atomic radius
- More shielding
- Therefore outer electrons are further away and less attracted to the positive nucleus- less energy required.
What is trend in reactivity for the group 2 elements?
- They lose electrons when they react, forming positive ions
- Therefore, reactivity increases as you go down the group as electrons are lost more easily.
What is trend in melting points for the group 2 elements?
They generally decrease down the group.
- They have metallic bonding and as you go down the group, the metal ions get bigger.
- However, the number of delocalised electrons per ion remains the same (2) and so does the charge on the ion.
- The larger the ionic radius, the further away the delocalised electrons are from the positive nuclei, so it takes less energy to break the bonds.
Where is the exception to the trend that melting points generally decrease down the group for group 2 elements?
Magnesium, because the crystal structure changes, so the melting point is lower than expected.
What is the equation for group 2 elements with water?
M(s) + 2H2O(l) → M(OH)2(aq) + H2(g)
What is trend in the solubility of group 2 hydroxides?
As you go down the group, the hydroxide solubility increases. Magnesium hydroxide is sparingly soluble.
What is trend in the solubility of group 2 sulfates?
As you go down the group, the sulfate solubility decreases. Barium sulfate is insoluble.
What is the test for sulfate ions?
- Add dilute HCl and then BaCl2 solution to the solution you’re testing.
- A white precipitate indicates the presence of sulfates.
Give a use of barium in medicine and why it’s safe to use.
Barium sulfate is used in barium meals because it’s insoluble so not poisonous and it’s opaque in X-rays.
Give some uses of magnesium and equations if necessary.
-Antacid/relieves indigestion
-For extracting titanium:
TiCl4 + 2Mg → Ti + 2MgCl2
Describe the process of extracting titanium.
Titanium(IV) oxide (TiO2) is first converted to Titanium(IV) chloride (TiCl4) by heating it with carbon in a stream of chlorine gas.TiCl4 is then purified by fractional distillation, before being reduced by Mg in a blast furnace at almost 1000 degrees Celsius.
Give a use of calcium.
CaO and CaCO3 can be used to remove flue gases
How can you identify group 2 cations? What are the results?
Flame test
Calcium, Ca2+ = brick-red
Strontium, Sr2+ = red
Barium, Ba2+ = green
Name the process where sulfur is removed from flue gases by reacting with an alkali such as CaCO3 or CaO.
Wet scrubbing
