Inorganic: Group 2/Group 7 Flashcards
What are three physical properties that have a trend in group 2?
- atomic radius
- first ionisation energy
- melting point
What is the trend for atomic radius in group 2?
as you go down the group, the atomic radius increases
-extra energy shells as you go down
What is the trend for first ionisation energy in group 2?
first ionisation energy decreases down the group
- extra electron shells as you go down, so extra inner e⁻ shields outer electrons from attraction of the nucleus
- more energy shells increases distance from the nuclear, which decreases nuclear attraction, so it is easier to lose outer e⁻
What is the GENERAL trend for melting point in group 2 ?
melting point GENERALLY decreases down the group. Group 2 metals normally form metallic structures
- down the group, metal ions get bigger
- BUT charge and no. of delocalised e⁻ stays the same
- larger ionic radius, reduced attraction
- takes less energy to break bonds
What type of bonding do group 2 metals normally form?
metallic bonds
What is the trend for reactivity of group 2 metals?
down the group, they get more reactive
- because they have a larger atomic radius os more distance and more inner shielding e⁻
- so easier to lose e⁻
- more reactive
What is the exception for trend of melting point of group 2 metals?
magnesium
it goes underneath line of best fit
Are all nitrates soluble?
Yes, all nitrates are soluble
there are no exceptions
Are all sulfates soluble?
most sulfates are soluble
exceptions:lead sulfate, barium sulfate, calcium sulfate
Are all chlorides, bromides and iodides soluble?
most of them are soluble
exceptions: SILVER chloride/bromide/iodide, LEAD chloride/bromide/iodide —-insoluble
Are all carbonates soluble?
most carbonates are insoluble
exceptions: sodium carbonate, potassium carbonate, ammonium carbonate
What are the group 2 reactions with water?
they form a metal hydroxide and hydrogen
the reaction gets more vigorous down the group
metal + water —–> metal hydroxide + hydrogen
Mg + water ——> MgO + H₂
What is the trend for solubilities of the hydroxides of group 2 metals?
as you go down the group, solubility increases
Mg(least soluble)
Ba (most soluble)
What is the trend for solubilities of the sulfates of group 2 metals?
as you go down the group, solubility decreases
Mg (most soluble)
Ba (least soluble)
Why is acidified barium chloride used to test for sulfate ions?
this is because it forms barium sulfate because it is one of the few sulfate compounds that is insoluble, so you can see the product
it is acidified because the acid removes any traces of carbonate ions (that would have also produced a white precipitate)
What is the use of magnesium in the extraction of titanium?
magnesium is used as the reducing agent
titanium is extracted from its ore as TiO₂ and cannot be reduced using carbon— because it forms TiC (carbide), which forms a brittle metal
so instead, they form TiCl₄, and then reduce with Mg
What is the use of MgOH is medicine?
-increases water in the intestines - to induce bowel movements and relieve constipation
-used as an antacid to relieve indigestion and heartburn
(antacid- neutralises excess stomach acid)
What is the use Ca(OH)₂ in agriculture?
used to neutralise acid in soils for plant growth
What are flue gases?
gases emitted by industrial exhausts and chimneys
What is the use of CaO or CaCO₃ in removal of SO₂ from flue gases?
burning fossil fuels to generate electricity produces sulfur dioxide which is a pollutant, this can be removed by reacting it with an alkali (wet scrubbing)
CaO and CaCO₃ are sprayed onto the gases
produces calcium sulfate
What is wet scrubbing?
reacting the flue gases with an alkali to remove SO₂
What is the use of BaSO₄ in medicine?
BaSO₄ is insoluble, it is opaque to X-rays (it shows up on an X-ray)
Used in Barium meals, to help diagnose problems with stomach, oesophagus or intestines because the BaSO₄
coats the soft tissues, making them show on the X-rays
Why can you not use other barium compounds for barium meals?
this is because other barium compounds would produce a solution which is poisonous but barium sulfate is insoluble so it forms a suspension, not a solution
What is the colour and state of fluorine at room temperature?
it is a pale yellow gas
