periodic table Flashcards
group 2 metal reaction with oxygen
2Ca (s) + O2 (g)—> 2CaO (s)
group 2 metal reaction with dilute acid
Ca (s) + 2HCl (aq) —-> CaCl2 (aq) + H2 (g)
group 2 metal reaction with water
Ca (s) + 2H2O (l) —-> Ca(OH)2 (aq) +H2 (g)
what happens to the solubility of metal hydroxides down the group
increases, so increased alkilinity
use of group 2 compounds
- neutralising acid soil
- indigestion remedies
- building and construction uses
neutralising acid soils equation
Ca(OH)2 (s) + 2HCl (aq) —-> CaCl2 (aq) +2H2O (l)
indigestion remedies
Mg(OH)2 + 2HCl —-> MgCl2 + 2H2O
CaCO3 + 2HCl —> CaCl2 + H2O + CO2
Building and construction uses
CaCO3 + 2HCl —> CaCl2 + H2O + CO2
electronegativity definition
the ability of an atom to attract the bonding pair of electrons in a covalent bond
electronegativity ______ as you go down group 7
decreases
halogens act as _____ agents
oxidising
halide ions act as _____ agents
reducing
colour of chlorine in water
pale green
colour of chlorine in cyclohexane
pale green
colour of bromine in water
orange
colour of bromine in cyclohexane
orange
colour of iodine in water
brown
colour of iodine in cyclohexane
Violet
the element with the ____ oxidising power will displace the other
higher
what do you use to test for halide ions?
silver nitrate
colour of chloride precipitate in silver nitrate
white
colour of bromide precipitate in silver nitrate
cream
colour of iodide precipitate in silver nitrate
yellow
solubility of silver halide compounds
AgCl soluble in NH3
AgBr insoluble in dilute NH3
AgI insoluble in concentrated NH3
chlorine disproportionation reactions
Cl2 + H2O —–> HClO + HCl
Cl2 + 2NaOH —-> NaCl + NaClO + H2O
benefits and risks of using chlorine
chlorine reacts with water and chlorate ions. ClO- kills bacteria in water to minimize diseases BUT is toxic and a respiratory irritant
order of halide tests
1) carbonate test
2) sulfate test
3) halide test
carbonate test
dilute acid (e.g. nitric acid)
- bubbles if +ve
sulfate test
barium nitrate
- white ppt if +ve
