metals, air and water

• metals at the bottom of the reactivity series (Ag, Au and Pt) are found as the uncombined metal in nature • metals below carbon can be extracted from their ores by reduction using carbon or carbon monoxide • metals above carbon in the reactivity series must be extracted using electrolysis

-when a more reactive metal replaces a less reactive metal in a dissolved compound

two or more metals mixed together to combine properties

• commonly used as catalysts • usually lose 2 electrons to for 2+ ions • high density • high mp • generally unreactive

• nitrogen (78%) • oxygen (21%) • argon (0.9%) • carbon dioxide (0.04%) • water vapour (up to 5% depending on humidity)

• these gases maintain temps on Earth high enough to support life • e.g. CO2, CH4 and water vapour • as energy from the Sun reaches the Earth, greenhouse gases allow short wavelength radiation, e.g. UV and visible light, to pass through, heating the Earth surface • as the Earth cools, it emits longer wavelength radiation, e.g. infrared radiation (IR) • greenhouse gases absorb IR, so some energy radiated from the Earth is trapped in the atmosphere -> temp rises • the higher the proportion of greenhouse gases in the atmosphere, the more energy is absorbed

CO2: -deforestation -burning of fossil fuels CH4: -cattle farming - rice fields - landfill sites

• caused by the release of poisonous/harmful chemicals into the air which directly/indirectly harm living things, damage the environment and buildings • most pollutants come from the burning of fossil fuels

• a colourless, odourless, poisonous gas • it binds more strongly to haemoglobin than oxygen and greatly reduces the amount of oxygen that the blood can carry around the body

• a poisonous, colourless, acidic gas with a choking smell • causes breathing difficulties and triggers asthma attacks • reacts with water and O2 in the atmosphere to produce sulfuric acid, one of the components of ‘acid rain’ • acid rain erodes stonework, increases metal corrosion, increases the leaching of soil (removal of important minerals) and is harmful to animal and plant life

• at the high temps and pressures generated within burner units, nitrogen in the air can react with oxygen to give different oxides of nitrogen • can react with O2 and water in the atmosphere to generate nitric acid, a component of acid rain • toxic • can trigger asthma attacks

• chemicals are added to water to make it safe to drink • chlorine gas is added in controlled quantities to sterilise the water as it kills harmful bacteria. • fluoride ions may be added as fluoride helps protect against tooth decay

metal + water -> metal hydroxide + hydrogen gas metal + steam -> metal oxide + hydrogen gas

-when a metal is able to be drawn out into a thin wire

-when a metal is able to be hammered or bent into shape without breaking or cracking

• cathode should be the object to be electroplated (e.g. iron) • anode should be the metal that you want to coat the object with (e.g. copper) • electrolyte should be a solution of the coating metal (e.g. copper sulphate)