Chemistry

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An element is a substance that contains only 1 type of atom

A mixture is physically combined, easy to separate and an element and compound stirred together

A compound - hard to separate, chemically combined and is 2 or more elements joined together

Atom - smallest particle that can exist on its own

Molecule - 2 or more atoms joined together

Atomic number - number at the bottom, tells you how many protons and electrons there are

Mass number - top number, total number of protons and neutrons, number of protons that which tells us which element the atom comes from

Number of neutrons = mass number - atomic number

Number of protons = number of electrons

Mass of reactants = mass of products

Limestone is used for - paper, cement, concrete, mortar, roads, buildings, steel, neutralize acidic soil

the positive test for carbon dioxide- bubble the gas through and lime water goes form clear to cloudy

carbon dioxide is produced when copper carbonate is heated

thermal decomposition - the splitting of a substance when heated

a stone roof of a building may be unsafe after a fire because when you heat limestone strongly, calcium carbonate breaks down to form calcium oxide which is powdery and brittle

To little amounts of sand in the lime mortar mixture and the mixture will shrink

Too much sand makes lime mortar weak

Disadvantages of quarrying limestone - it crates huge ugly holes which scar the landscape, the quarrying process creates noise and dust, it destroys the habitasts of birds and animals, the limestone needs to be transported away which created noise pollution

Advantages of quarrying limestone - limestone provides things that people want such as houses and roads, limestone products are used to neutralize acidic soil, the quarry and associated businesses provides jobs and brings more money into the local economy which could lead to local improvements

Metals more reactive than carbon can be extracted by electrolysis

Most copper is extracted by smelting copper-rich ores.

Copper can be extracted form copper solutions by electrolysis.

Electrolysis is also used to purify impure copper from smelting

Scientists are developing new ways to extract copper that used low-grade copper ores:

- bacteria is used in BIO LEACHING

- plants are used in PHYTOMINING

aluminium and titanium are useful because they resist corrosion.

Aluminium requires the electrolysis of molten aluminium oxide to extract it as it is too reactive to reduce using carbon

Aluminium and titanium are expensive because extracting them from their ores involves many stages and requires large amounts of enegy

Fractional distillation is used to separate gasses in the air.

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