Group2 Flashcards
What are the trends of atomic radius as you go down Group 2?
As you go down group 2 the atomic radius increases because the number of energy levels is increasing.
What are the trends in first ionisation energies ?
As you go down group 2 the first ionisation energies decreases.
This is because the outer electrons are in a higher energy level so the attraction between the nucleus and outer shell electron decreases,
.
What are the trends in melting points down group 2
Decreases down group 2
As u go down the group delocalised electrons are further away from the positive nucleus
So there will be a weaker attraction between positive ions and delocalised electrons
Thus the strength of the metallic bond decreases
Why is the third ionisation energy of magnesium higher than the second ionisation energy of magnesium?
Electron is removed from the 2p sub shell which is less shielded than 3s
What are the group 2 metals reactions with water?
Magnesium-very slow reaction with cold water
Calcium-fizzes in water and after a time a white solid forms(sodium calcium hydroxide) which is slightly soluble in water
Sodium - fizzes in water and forms a colourless solution
Barium -fizzes in water and forms a colourless solution
What happens when you burn magnesium!
Magnesium burns with a white flame and forms a white solid when you react it with steam instead of cold
What trend do you observed with solubility Group 2 metal hydroxides?
More soluble down group 2
What trends do you see with the solubility of Group metal sulfate?
Less soluble down group 2
Balanced equation between magnesium and cold water
Mg(s) + 2H2O(l) —> Mg(OH)2(aq)+ H2(g)
Balanced equation for magnesium and steam
Mg(s) + H2O(g)—> MgO(s) + H2(g)
What are the three types of calcium compounds and their uses?
Three different calcium compounds are used commonly in agriculture,
construction and iron extraction:
Limestone - this is impure calcium carbonate
Quicklime - this is calcium oxide, formed by the thermal decomposition of calcium carbonate
Slaked lime - this is calcium hydroxide formed when water is added to quicklime
Ca(OH)2 (s) + 2H+ (aq) → Ca2+ (aq) + 2H2O (l)
What are all three of the calcium compounds used for in agriculture ?
All three materials are used in agriculture to raise the pH of the soil
Over time, the soil becomes more acidic while the optimum pH for many crops to grow is at around 6-6.5
The compounds are all bases and react with the acids in the soil and raise the pH of the soi
Why is calcium carbonate more commonly used in agricultural lime?
Calcium carbonate is more commonly used in agricultural lime as it is cheaper and safer to handle
However, due to calcium carbonate being largely insoluble, it acts more slowly than calcium hydroxide
What is another use of calcium compounds?
Calcium compounds are also used to remove sulfur dioxide from flue gases in a process known as sulfur scrubbing
What is barium used for ?
Barium is used in medicine in the form of barium sulfate, BaSO4
A barium meal or barium swallow containing BaSO4 is given to a patient who needs an X-ray on their intestines
Barium absorbs X-rays which means the gut shows up white on the image
Despite barium being toxic why can it be used in this form?
Barium is toxic though can be used in this form because
Barium sulfate is insoluble so is not absorbed into the blood
The barium meal or swallow is only a small amount for the patient to ingest
What can be used to test for sulfate ions ?
Barium chloride or barium nitrate solution can be used in the test for sulfate ions, SO42-
What is magnesium hydroxide used for ?
Magnesium hydroxide, Mg(OH)2, is partially soluble in water and is used in suspension (known as ‘milk of magnesia’) to neutralise excess acid in the stomach and treat constipation
Mg(OH)2 (s) + 2HCl (aq) → MgCl2 (aq) + 2H2O (l)
Why is magnesium hydroxide safe to use?
It is safe to use as the magnesium hydroxide is only partially soluble making the solution only slightly alkaline (pH ≅ 10) due to the low OH- concentration
How is magnesium used in extraction?
Magnesium is also used in the extraction of titanium from its ore, TiO2
TiO2 is heated in a stream of chlorine, in the presence of coke, to produce TiCl4
TiO2 (s) + 2C (s) + 2Cl2 (g) → TiCl4 (g) + 2CO (g)
How is calcium extracted from its compound
The titanium is extracted from its chloride by reduction with magnesium (sodium can also be used)
TiCl4 (g) + 2Mg (l) → Ti (s) + 2MgCl2 (l)
