Group 2 Flashcards
what are the trends in atomic radius down group 2?
Atomic radius increases down the group:
- shielding increases
- outer electron is further from the nucleus meaning its less attracted
what are the trends in melting point ?
Melting points decrease down the group.
- ionic radius increases
- shells increase
- distance between delocalised e- and positive nucleus increase down group and strength of metallic bonding decreaes
- less energy required to overcome bonds
what are the trends in first ionisation energy down group 2?
ionisation energy decreases as you go down a group:
1-atomic radius/size increases =decreases i.e
2-electron shielding increases=i.e decreases
3-nuclear charge increases i.e
write an equation for 1st & 2nd ionisation energy:
1st ionisation energy:
X(g)→X+(g)+e-
2nd ionisation energy:
X+(g)→X2+(g)+e-
what are the trends in reactivity of group 2?
Reactivity of group 2 metals increases down the group:
- ionisation energy gets smaller
- shielding increases
- atomic radius increases as the outer electrons are held further from the nucleus
- its easier to loose e-
What is the reaction with group 2 and oxygen?
The group 2 metals will burn in oxygen.Mg burns with a bright white flame.
2Mg + O2 → 2MgO
-MgO is a white solid with a high melting point due to its ionic bonding.
what is the reaction between group 2 and steam?
Mg(s)+H2O→MgO(s)+H2(g)
- mg would burn with a bright white flame
- rapid reaction
what is the reaction between group 2 elements and warm water?
Mg (s) + 2H2O(l) → Mg(OH)2 (aq) + H2 (g)
- slower reaction than with steam
- no flame
what is the reaction between group 2 metals and cold water?
Ca + 2 H2O (l) → Ca(OH)2
(aq) + H2(g)
-The hydroxides produced make the water alkaline
(if they are soluble in water).
-observations:
fizzing, (more vigorous down group) ,the metal dissolving, (faster down group) ,the solution heating up (more down group) ,with calcium a white precipitate appearing
(less precipitate forms down group with other metals)
what is titanium used for?
Titanium is a very useful metal because it is abundant, has a low density and is corrosion resistant – it is used for making strong, light alloys for use in aircraft
steps in extracting titanium:
1-titanium ore a solid (Ti02)is converted to titanium chloride a liquid (TiCl4) by heating it with carbon and chlorine gas at 900 degrees
2-The TiCl4 is purified by fractional distillation in an argon atmosphere
3. The Ti is extracted by Mg in an argon atmosphere at 500 degrees Celsius
why is titanium expensive?
- The expensive cost of the Mg
- This is a batch process which makes it expensive because the
process is slower (having to fill up and empty reactors takes
time) and requires more labour and the energy is lost when the
reactor is cooled down after stopping - The process is also expensive due to the argon, and the need to
remove moisture (because TiCl4
is susceptible to hydrolysis). - High temperatures required in both steps
why can’t titanium be extracted with carbon or by electrolysis?
titanium carbide (TiC) it is formed rather than titanium
-Titanium cannot be extracted by electrolysis
because it has to be very pure
using mg to extract titanium
equation:
TiCl4 + 2Mg → Ti + 2 MgCl2
what is simplest ionic equation?mg(oh)2
Mg2+(aq)+2OH- (aq)→ mg(OH)2(s)
