chemistry unit 1

label the parts of an atom.

the nucleus (protons and neutrons ) electrons occupy shells around the nucleus.

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Describe how could work out the electronic structure of an atom given its atomic number.

number of protons= number of electrons so use the 2,8,8 rule

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describe the process of ionic bonding.

A compound which is formed from a metal and a non-metal consists of ions. The metal atoms lose electrons to form positive ions and the non-metals gain electrons to for negative ions. The opposite charges of ions mean they they're strongly attracted t

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what is covalent bonding?

A covalent bond is when two non-metals share electrons to fill up their outer shells.

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what is an element?

elements consist of one type of atom only.

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what is a compound?

Different elements react when atoms form chemical bonds with other atoms to form compounds.

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write out the symbol equation for the decomposition of limestone

calcium carbonate ------calcium oxide+ carbon dioxide

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What products are produced when limestone reacts with an acid?

calcium sulfate , carbon dioxide , water.

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what is calcium hydroxide used for?

calcium hydroxide ( limewater ) is used to test if carbon dioxide present as liewater turns cloudy.

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name 3 building materials made from limestone.

1) concrete 2)mortar 3) cement

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name some of the advantages and disadvantages of limestone quarrying.

1) limestone provides things that people want like houses and roads. 2) limestone produces chemicals like dyes, paints and medicines. 3) limestone products are used to neutralise acidic soil. Acidity in lakes and rivers caused by acid rain is also

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name some of the advantages and disadvantages of limestone quarrying. (2)

neutralised by limestone products. 3) limestone is used in power station chimneys to neutralise sulfure dioxide. 4) provides people with jobs so brings more money into local economy.

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name some of the advantages and disadvantages of limestone quarrying. (3)

5) limestone is widely available and is cheaper than granite or marble. 6) limestone is hard wearing compared to ones like marble and looks v attractive. 7) quarrying processes like blasting rocks apart make a lot of noise and dust. 8)

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name some of the advantages and disadvantages of limestone quarrying. (4)

8)quarrying destroys the habitats of animals and birds. 9) the limestone needs to be transported away so energy, noise and pollution.

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what is the definition of an ore?

ores contain enough metal to make extraction worthwhile.

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Explain why zinc can extracted by carbon but magnesium cant

Because zinc is lower than carbon on the reactivity series, because carbon only take the oxygen away from the metals which are less reactive than carbon itself is.

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Give a reason why aluminium is an expensive metal.

aluminium requires extraction by electrolysis which uses energy.

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what is electrolysis?

electrolysis means splitting up with electricity.

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Describe the process of purifying copper by electrolysis.

1) Electrons are pulled off copper atoms at the anode, causing them to go into solution as cu2+ ions. 2) cu2+ ions near the cathode gain electrons and turn back into copper atoms. 3) the impurities are dropped at the anode as sludge, while c= cathode

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Describe how scrap iron is used to displace copper from solution.

if some iron is put in a solution of copper sulfate, the more reactive iron will kick out the less reactive copper from the solution. You end up with iron sulfate solution and copper metal.

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What is the name of the method where where plants are used to extract metals from soil.

phytomining

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Give three reasons why its good to recycle metals

1) mining and extracting metals takes a lot of energy, most of which comes from fossil fuels . FFs will run out so its important to conserve them. 2) Recycling metals only uses a small fraction of the energy needed to mine and extract new metal

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give 3 properties of metals

1) strong 2) good conductors of heat + electricity 3) shiny

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briefly describe two problems with metals.

they corrode when exposed to air and water and get tired

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what is the problem with using iron straight from the blast furnace and very pure iron?

it doesnt have many uses as it contains impure iron which is brittle and very pure iron has a regular arrangement of identical atoms. The layers of atoms can slide over each other, which makes the iron to soft and bendable

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Give two examples of alloys and say whats in them

bronze = copper + tin , cupronickel= copper + nickel

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what does crude oil consist of? what does fractional distillation do to crude oil?

crude oil is a mixture of hydrocarbons and fractional distilation splits crude oil into separate groups of hydrocarbons.

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what is the general formula for an alkane?

CnH2n+2

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is a short-chain hydrocarbon more viscous than a long-chain hydrocarbon? is it more volatile?

shorter molecules are LESS viscous and more volatile.

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Name three pollutants released into the atmosphere when fuels are burned.

1) carbon dioxide 2) sulfur dioxide 3) nitrogen oxide

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list 3 ways of reducing acid rain.

1) sulfur can be removed from the fuels before there burnt 2) reduce usage of fossil fuels 3) acid gas scrubbers that remove the gas once its released.

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has the theory of global dimming been proven yet?

no not enough evidence yet.

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list three alternative ways of powering cars. What are the pros and cons of each?

ethanol can be produced from plants by fermentation, pros: the co2 realised when its burnt was taken in by the plant as it grew. cons: engines need to be converted. BIodiesel is a form of biofuel. It is made by vegtable oils pros: carbon neutral

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list three alternative ways of powering cars. What are the pros and cons of each? (2)

cons: we cant make enough to replace diesil. Hydrogen gas can be used to power vehicles pros: only realises water which is clean cons: you need special expensive engines.

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1) what is cracking? why is it done?

cracking is splitting up long chain hydrocarbons its done to get useful products like eg. petrol

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give a example of substance cracked and the products.

diesil= petrol , paraffin, ethene for plastics

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what kind of carbon-carbon bond do alkenes have?

c=c double bond

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what is the general formula of an alkene

CnH2n

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when ethene is hydrated with steam, what substance is formed?

ethanol

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what are polymers? what kind of substances can polymers make?

polymerisation is joining together lots of small alkene molecules to form very large molecules eg. poly ethene and poly propane

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give two factors that affect the physical properties of a polymer

1)tempreture 2) pressure

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list 4 uses of polymers

1) plastic bags 2) tooth fillings 3) biodegradable packaging 4) waterproof coatings for fabrics

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why might polymers become more expensive in the future?

oil is running out so polymers will become expensive

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why do some oils need to be distilled after they have been extracted?

distillation refines oil, and removes water, solvents and impurities.

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list two advantages of cooking with oil.

different flavourings and increase the energy

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apart from cooking, list a use of vegetable oils

vegetable oils can be used to produce fuels

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what kind of carbon-carbon bond do unsaturated oils contain?

double bond

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what happens when you react unsaturated oils with hydrogen?

they can be hardened by reacting them with hydrogen in the presence of a nickel catalyst at about 60 degrees celcius

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why do some foods contain partially hydrogenated vegetable oil instead of butter?

because these oils are a lot cheaper than butter and they keep longer. So makes them cheaper and gives a longer shelf life.

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what is an emulsion? give an example

emulsions are made of oil and water. Emulsions can also help oil and water mix for example mayonnaise, salad dressing, and whipped cream

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how do emulsifiers keep emulsions stable?

the hydrophilic end of each emulsifier molecule latches onto water molecules. The hydrophobic end of each emulsifier molecule latches up to a oil molecule.

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suggest one problem with adding emulsifiers to food.

some people are allergic to certain emulsifiers.

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Give one reason why Alfred Wegeners theory of continental drift

not enough evidence

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what can be found beneath the earths crust?

the mantle

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explain continental drift

there was once a Pangea ( supercontinent), Then broke into chunks and drifted apart due to convection currents.

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why cant scientists not accurately predict volcanoes and earthquakes?

tectonic plates move and collide randomly.

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Name the two main gasses that make up the atmosphere today.

nitrogen and carbon dioxide

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Explain why todays atmosphere is different from the early earths atmosphere.

Because volcanoes gave out gasses . There had been alot of co2, no oxygen, water vapur and small amounts of ammonia and methane. The oceans formed when the water vapour condensed. Green plants evolved and produced oxygen by photosynthesis bceause a

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Explain why todays atmosphere is different from the early earths atmosphere. (2)

of co2 dissolved into the ocean and the green plants and algae also absorbed some of the co2. These plants died and were buried under layers of sediment. Along with skeletons and shells of marine organisms that had slowly evolved. The carbon inside

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Explain why todays atmosphere is different from the early earths atmosphere. (3)

of them became locked up so when we burn fossil fuels today this locked up carbon is released and the concentration of co2 in the atmosphere rises. The build of oxygen in the atmosphere killed off early organisms but allowed more complex organisms to

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Explain why todays atmosphere is different from the early earths atmosphere. (4)

evolve and flourish. The oxygen also created the ozone layer which blocked harmdul rays from the sun and enabled complex organisms to evolve. And there is virtually no co2 left now.

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what is meant by the primordial soap?

billions of years ago the earths atmosphere was rich in nitrogen, hydrogen, ammonia and methane. Lightining struck, causing a chemical reaction between the gasses. Resulting in the formation of amino acids. The amino acids collected in the primoridal

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what is meant by the primordial soap? (2)

soap - a body of water out of which life gradually crawled. The amino acids gradually combined to produce organic matter which eventually evolved into simple living organic matter

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why do we fractionally distil air?

we fractionally distil air to get a variety of products eg. nitrogen and oxygen for use in industry

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The burning of fossil fuels is causing a rise in the level of carbon dioxide in the atmosphere how is this affecting the oceans and the climate?

burning fossil fuels releases co2 and increase in co2 causes global warming ( a type of global warming) The oceans are a natural store of co2 they absorb it from the atmosphere, the extra co2 is making them acidic, which is bad for the sea life.

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what does the mass number and the atomic number represent?

the mass number represents the total number of protons and neutrons, while the atomic number represents the number of protons

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what are the relative masses of of the three types of particles in an atom?

proton = 1 , neutron = 1 , electron = very small

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what is a compound?

compounds are formed when atoms of two or more elements are chemically combined together.

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define the term isotope.

isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons

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Describe the process of ionic bonding.

in ionic bonding, atoms lose or gain electrons to form charged particles called ions which are then strongly attracted to onr another, because of the attraction of opposite charges + and -

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describe the structure of a crystal of sodium chloride.

giant ionic lattices : the ions form a closely packed regular lattice arrangement. These are very strong electrostatic forces of attraction between the oppositely charged ions, in all directions . A single crystal of sodium chloride is one giant ioni

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list the main properties of ionic compounds.

1) high melting points 2) high boiling points due to the strong attraction between ions. It takes a larger amount of energy to overcome this attraction. 3) when ionic compounds melt, the ions are free to move , and they'll carry electric current.

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what type of ion do elements from the following groups from? a) group 1 b) group 7

group one looses one so + eg. LI+ and group 7 gains an electron so - eg. F-.

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use information from the periodic table to help you work out the formulas of these ionic compounds a) potassium chloride b) calcium chloride

A) KCL b) CACL

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What is covalent bonding?

sometimes atoms prefers to make covalent bonds by sharing electrons with other atoms.

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what are the two types of covalent substances? give three examples of each

1) simple molecular substances eg. chlorine , oxygen , water 2) Giant covalent structures eg. diamond , graphite , silicon dioxide

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Explain why alloys are harder than pure metals

different elements have different sized atoms. So when another metal is mixed with a pure metal, the new metal atoms, making it more difficult for them to slide over each other. So alloys are harder.

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Give an example of a smart material and describe how it behaves.

nitinol ( shape memory alloy) when its cool you can bend it and twist it like rubber. If you heat it above a certain tempreture it goes back to a remembered shape.

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what are nanoparticles? Give two different applications of nanoparticles.

Nanoparticles are really tiny particles ( 1-100 nanometres ) nanoparticles are used as fullerenes. These are molecules of carbon, shaped like hollow balls or closed tubes. The carbon atoms are arranged in hexagon rings. Nanoparticles=catalysts.

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Explain thermosoftening polymers.

tangled chains held together by WIF no cross-linking between chains. The forces between the chains are really easy to overcome. So v easy to melt. When it cools, the polymer hardens into a new shape. You can melt and remould many times.

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Explain thermosetting plastics.

thermosetting plastics have stronger Intermolecualr forces. between cross links. Solid structure. The polymer doesnt soften when its heated. They are tough, strong, hard and rigid.

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Define relative atomic mass and relative formula mass.

the relative atomic mass ( Ar) is the mass number of an element. The relative formula mass is the over all Ar of a compund added together.

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what is the link between moles and relative formula mass?

one mole of a substance is equal to its Mr in grams.

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Explain how paper chromatoraphy can be used to analyse the dyes used in sugar.

Extract the colour from a food sample by placing it in a small cup and droping a few solvents. Put spots of the coloured solution on a pencil baseline on filter paper. Roll up the sheet and put in a beaker with some solvent. Then count the amountofsp

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what are the 4 factors that affect the rate of reaction?

1) temperature 2) surface area 3) catalyst 4) concentration.

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describe one way of measuring the rate of reaction.

precipitation: this is when the product of a reaction is a precipitate which clouds the solution. Observe a mark through the solution and measure how long it takes for it to disappear.

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describe another way of measuring the rate of reaction.

change in mass: measure the speed of a reaction that produces of gas using gas balance. As the gas is released the mass disappearing is easily measured on the balance. The quicker the reading on the balance drops, the faster the reaction.

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describe the third way of measuring the rate of reaction

the volume of gas given off: use a gas syringe. Measure the volume of gas given off during a given time. The more gas given off during a given time interval, the faster the reaction.

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A student carries out an experiment to measure the effect of surface area on the reaction between marble and hydrochloric acid. He measures the amount of gas given off at regular intervals. What factors must he keep constant for it to be a fair test?

temperature and concentration of hydrochloric acid

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explain how higher temperature increase the frequency of successful collisions between particles.

when the temperature is increased the particles all move quicker if they're moving quicker, they're going to collide more often.

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explain how higher concentration increases the frequency of successful collisions

higher concentration means there are more particles of reactant knocking about between the water molecules which makes the collisions between the important particles more likely.

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explain how a larger surface area increases collisions.

if one of the reactants is a solid then breaking it up into smaller pieces will increase the total surface area . This means the particles around the solution will have more area to work on , so there'll be more frequent collisions.

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what is activation energy?

activation energy is the minimum amount of energy needed for the particles to react.

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what is the definition of a catalyst.

A catalyst is a substance which speeds a reaction, without being changed or used up in the reaction.

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3 advantages and 3 disadvantages of using catalysts in industry.

+ 1) increase rate of reaction so saves a lot money 2) catalysts allow the reaction to work at a much lower temperature , That reduces the energy used up in the reaction (energy cost) 3) good for commercial reasons eg. most industrial reactions use

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3 advantages and 3 disadvantages of using catalysts in industry. (2)

them. - 1) expensive to buy 2) catalysts can be poisoned by impurities, so they stop working. 3) different reactions use different catalysts, so if you make more than one product at your plant, you'll need to buy catalysts for them.

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what is an exothermic reaction? give three examples

An exothermic reaction is one which transfers energy to the surroundings, usually in the form of heat and usually shown by a rise in tempreture. 1) eg. burning fossil fuels 2) neutralisation reactions 3) oxidation reactions.

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The reaction to split ammonium chloride into ammonia and hydrogen chloride is endothermic. What can you say for certain about the reverse reaction?

It will be exothermic.

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what does the PH scale show?

The PH scale is a measure of how acidic or alkaline a solution is. The strongest acid has PH 0. The strongest alkali is PH 14. A neutral substance has PH 7 (pure water)

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what type of ions are always present in a) acids b) alkalis

a) H+ ions b) OH-ions

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What is neutralisation? write down the general equation for neutralisation in terms of ions.

The reaction between acids and bases. H+ + OH- --- H2O

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write down the state symbol that means 'dissolved in water'

(aq)

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what is the general equation for reacting an acid with a metal?

Acid + Metal --- Salt + Hydrogen

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Name a metal that doesn't react at all with dilute acids?

Copper

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what type of salts do hydrochloric acid and sulfuric acid produce?

Chloride salts and Sulfate Salts.

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what type of reaction is acid + metal oxide and acid + metal hydroxide?

neutraliosation reactions

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what is the product of a reaction between ammonia and nitric acid useful for? balanced symbol equation for ammonia and nitric acid?

Fertiliser. NH3 + HNO3------ NH4NO3

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suggest a suitable metal oxide/hydroxide to mix to form the following salts a)copper chloride b) potassium chloride c) sodium sulfate d) magnesium nitrate

a) Hydrochloric acid + copper oxide b) Hydrochloric acid + Potassium hydroxide c) Sulfuric acid + Sodium hydroxide d) nitric acid + magnesium oxide

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Iron chloride can be made by mixing iron hydroxide (an insoluble base) with hydrochloric acid. Describe the method you would use to produce pure solid iron chloride in the lab.

1) you add the Iron hydroxide to the hydrochloric acid the solid will dissolve in the as it reacts. You will now when all the acid has been neutralised because the excess Iron hydroxide will just sink to the bottom of the flask. 2) Then filter out th

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Iron chloride can be made by mixing iron hydroxide (an insoluble base) with hydrochloric acid. Describe the method you would use to produce pure solid iron chloride in the lab. (2)

2) Then filter out the excess Iron hydroxide to get the salt solution. 3) then evaporate some of the water (to male the solution more concentrated) then leave the rest to evaporate slowly. This is called crystallisation.

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how can you tell when a neutralization reaction is complete if both the base and the salt are soluble in water?

You need to use indicator to see if the reaction id finished.

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give a practical use for precipitation reactions

precipitation can be used to remove poisonous ions (e.g lead) from drinking water.

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what is electrolysis?

If you pass an electric current through an ionic substance that's molten or in solution it breaks down into the elements it's made of. This is called electrolysis.

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Explain why only liquids can be electrolysed

It requires a liquid to conduct the electricity called the electrolyte. Electrolyte contains free ions they are usually the molten or dissolved ionic substances. In either case it's the free ions that conduct electricity and allows it to work.

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give one industrial use of sodium hydroxide and two uses of chlorine

Sodium hydroxide is a very strong alkali and is used widley in the chemical industry e.g making soap. Chlorine: bleach and plastics.

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why is cryolite used during the electrolysis of aluminum oxide?

Aluminum oxide has a very high melting point of over 2000 c - so melting it i very expensive. Instead the aluminum oxide is dissolved in molten cryolite . This brings the temperature down to about 900 c which makes it much cheaper and easier.

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give two different uses of electroplating

decoration and conduction

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chemistry unit 1

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