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CHEM REV TEST 3 - Coggle Diagram
CHEM REV TEST 3
Halogens
Chemical Properties
as it goes down the group, the atomic size increases due to increasing number of electron shells
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as outermost electron is further away from the positively charged nucleus, the efoa for valence electron from other atoms decreases down the group
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Physical Properties
melting and boiling point of halogens increases down the group as size of molecules increases (more electron shells, increase SA) and there is more weak imfa down the group that needs more energy to overcome it
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exists as simple covalent diatomic molecules held by weak imfa and very little energy needed to overcome these weak forces
fl and cl are gases, br is liq, i is sol
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KPT
Solid
the particles of a solid
-closely packed together in an orderly manner
-held together by strong foa
-have enough kinetic energy to only vibrate in fixed positions
-cannot move about freely
-has a fixed volume as particles are already very closely packed thus cannot be compressed, fixed volume
Gas
the particles of a gas
-spread far apart from one another
-weaker foa compared to liq
-a lot of kinetic energy and not held in fixed positions
-can move about rapidly in any direction
Liquid
the particles of a liquid
-arranged in a disorderly manner
-have weaker foa between particles than solid
-have more kinetic energy than particles of same substance in solids and are not held in fixed positions
-can move freely throughout the liquid
-has a fixed vol cos even though its particles are further apart than solid, it is still packed quite closely tgt making it unable to be compressed and thus fixed vol
Air and Air Pollution
Air Pollutants
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ozone at low altitudes
source : in sunlight, nitrogen oxides react with unburnt hydrocarbonds to produce ozone which i the main component of smog
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carbon monoxide
source of pollutant : when there is incomplete combustion of carbon containing substances in insufficient supply of oxygen
effect : a poisonous gas that binds with haemoglobin and prevents oxygen from being transported around the body
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sulfur dioxides
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effect ; dissolves in rain to form acid rain which corrodes limestone buildings and metal structure
causes breathing difficulties
nitrogen oxides
source : heat energy released by lightning activity causes itrogen and oxygen in the air to react together to form NO and NO2.
nitrogen in air reacts with oxygen in the air at high temperatures to form nitrogen cars
dissolves in rain to form acid rain which corrodes buildings and metal structures
causes breathing difficulties
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Composition of air : 78% nitrogen, 21%oxygen, 0.035 carbon dioxide, 0.975 noble gas
Carbon Cycle
to regulate the concentration of carbon dioxide in the atmosphere, the rate of removal of co2 equals to the rate of production of co2.
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if there is more co2 produced than it is removed, it will result in global warming that leads to melting of glaciers and sea level rise
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