AQA Chemistry Unit 1

Pregunta	Respuesta
What is an ELEMENT?	An element is a substance that is made of only one sort of atom.
Explain what atoms are and what they contain.	All substances are made from tiny particles called atoms. An atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons.
State the charge for the 3 components of an atom:	- proton = +1 - neutron = 0 - electron = -1
Atoms ahve a neutral (or no) charge. WHY???	The number of electrons in an atom is equal to the number of protons in its nucleus, therefore atoms have no overall electrical charge.
What is the ATOMIC NUMBER???	The atomic number of an atom is the number of protons it contains.
What is the MASS NUMBER???	The mass number of an atom is the total number of protons and neutrons it contains. The mass number of an atom is never smaller than the atomic number. It can be the same; it is usually bigger.
How many electrons are required in each shell?	- first = 2 - second = 8 - third = 8
You CANNOT find a compound on the periodic table. WHY???	You will never find a compound in the periodic table because these consist of two or more different elements joined together by chemical bonds.
Explain the reactions of group 1 elements with oxygen.	The group 1 metals react vigorously with oxygen to form metal oxides. Lithium burns with a red flame, sodium with a yellow-orange flame, and potassium burns with a lilac flame.
Group 1 the called the...	ALKALI METALSSSSSSSSSSS
Group 0 is called the...	NOBLE GASESSSSSSSSSSS
Elements in Group 1 MUST be stored in oil. WHY???	Because they react with oxygen.
Elements in Group 0 are unreactive. WHY???	They are stable - this is because their outer shell is filled to its maximum capacity (eg. Helium's outer shell is filled with 2 electrons).
Describe what happens to METALS and NON-METALS during IONIC BONDING.	- metal atoms lose electrons to form positively charged ions. - non-metal atoms gain electrons to form negatively charged ions.
Write a balanced equation for a Copper Oxide reaction (HIGHER TIER ONLY) NOTE - FOUNDATION QUESTION IS ON THE NEXT CARD FOR ANYBODY TAKING FOUNDATION UNIT 1)	2Cu + O2 → 2CuO
Write an equation for a Copper Oxide reaction (FOUNDATION TIER ONLY)	copper + oxygen → copper oxide
State an important rule when balancing equations (HIGHER TIER ONLY)	NEVER change a formula to balance an equation!!!
The mass is conserved during a chemical reaction. WHY???	Because the total mass of products after the reaction is the same as the total mass of the reactants at the start.
What is LIMESTONE???	Limestone is a sedmentary rock that is made up of Calcium Carbonate (CaCO3).
EXPLAIN THE 4 STAGES OF THE LIEMSTONE CYCLE.	1. CaCO3 → CaO + CO2 2. CaO + H20 → CA(OH)2 3. CA(OH)2 → limewater 4. CA(OH)2 + CO2 → CaCO3
Calcium carbonate breaks down when heated strongly. What is the name of this reaction?	THERMAL DECOMPOSITION.
Explain what happens to metals in the reactvity series (high up) when it comes to decomposition.	Metals high up in the reactivity series (such as sodium, calcium and magnesium) have carbonates that need a lot of energy to decompose them. Indeed, not all the carbonates of group 1 metals decompose at the temperatures reached by a Bunsen burner.
Explain what happens to metals in the reactvity series (lower down) when it comes to decomposition.	Metals low down in the reactivity series, such as copper, have carbonates that are easily decomposed. This is why copper carbonate is often used at school to show thermal decomposition. It is easily decomposed and its colour change, from green copper carbonate to black copper oxide, is easy to see.
How is MORTAR made???	Mortar (used to join bricks together) is made by mixing cement with sand and water.
How is CONCRETE made???	Concrete is made by mixing cement with sand, water, and aggregate (crushed rock).
Explain the advantages and disadvantages of various building materials. (1/2)	Limestone, cement and mortar slowly react with carbon dioxide dissolved in rainwater and wear away. This damages walls made from limestone, and leaves gaps between bricks in buildings. These gaps must be filled in or ‘pointed’. Pollution from burning fossil fuels makes the rain more acidic than it should be, and this acid rain makes these problems worse.
Explain the advantages and disadvantages of various building materials. (2/2)	Concrete is easily formed into different shapes before it sets hard. It is strong when squashed, but weak when bent or stretched. However, concrete can be made much stronger by reinforcing it with steel. Some people think that concrete buildings and bridges are unattractive.
Explain the main advantages of the limestone industry.	- Limestone is a valuable natural resource, used to make things such as glass and concrete. - Limestone quarrying provides employment opportunities that support the local economy in towns around the quarry.
Explain the main disadvantages of the limestone industry.	- Limestone quarries are visible from long distances and may permanently disfigure the local environment. - Quarrying is a heavy industry that creates noise and heavy traffic, which damages people's quality of life.
What are ORES?	Ores are naturally occurring rocks that contain metal or metal compounds in sufficient amounts to make it worthwhile extracting them
What are ALLOYS?	An alloy is a mixture of two elements, one of which is a metal.
Alloys are more useful than metals. WHY???	This is because alloys often have properties that are different to the metals they contain. This makes them more useful than the pure metals alone. For example, alloys are often harder than the metal they contain.
What is a METAL ORE???	A metal ore is a rock containing a metal, or a metal compound, in high enough concentration to make it economic to extract the metal.
Describe different uses of extraction for different ores.	The reduction method depends on the reactivity of the metal. For example, aluminium and other reactive metals are extracted by electrolysis, while iron and other less reactive metals may be extracted by reaction with carbon or carbon monoxide.
Gold does not have to be extracted. WHY???	Because gold is so unreactive, is found as the native metal and not as a compound. It does not need to be chemically extracted from its ore, but chemical reactions may be needed to remove other elements that might contaminate the metal.
DEscribe the properties of the TRANSITION METALS:	- they are metals. - they are good conductors of heat and electricity. - they can be hammered or bent into shape easily.
How is iron extracted???	Iron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as haematite contain iron oxide. The oxygen must be removed from the iron oxide to leave the iron behind. Reactions in which oxygen is removed are called reduction reactions.
Write a BALANCED EQUATION for a reaction in the blast furnace that includes Carbon Dioxide (HIGHER TIER ONLY).	2Fe2O3 + 3C → 4Fe + 3CO2
Write an equation for a reaction in the blast furnace (FOUNDATION TIER ONLY).	iron oxide + carbon → iron + carbon dioxide
Carbon has the ability to push or displace iron from iron oxide. WHY???	Beacuse it is more reactive than iron.
Write a BALANCED EQUATION for a reaction in the blast furnace that includes Carbon Monoxide (HIGHER TIER ONLY).	Fe2O3 + 3CO → 2Fe + 3CO2
Write an equation for a reaction in the blast furnace that includes Carbon Monoxide (FOUNDATION TIER ONLY).	iron oxide + carbon monoxide → iron + carbon dioxide
Why is opper useful?	Copper is soft and easily bent and so is a good conductor of electricity, which makes it useful for wiring. Copper is also a good conductor of heat and it does not react with water. This makes it useful for plumbing, and making pipes and tanks.
PHYTOMINING:	Some plants absorb copper compounds through their roots. They concentrate these compounds as a result of this. The plants can be burned to produce an ash that contains the copper compounds.
BIOLEACHING:	Some bacteria absorb copper compounds. They then produce solutions called leachates, which contain copper compounds.
SCRAP ION:	Copper can also be extracted from solutions of copper salts using scrap iron. Iron is more reactive than copper, so it can displace copper from copper salts. For example: iron + copper sulfate → iron sulfate + copper
OH NO!!! WE ARE RUNNING OUT OF COPPER-RICH ORES!!! WHAT ARE WE GONNA DO???	Research is being carried out to find new ways to extract copper from the remaining low-grade ores, without harming the environment too much. This research is very important, as traditional mining involves huge open-cast mines that produce a lot of waste rock.
Aluminium and Titanium are useful. WHY???	Aluminum and titanium are two metals with a low density. This means that they are lightweight for their size. They also have a copper layer of their oxides on the surface, which stops air and water getting to the metal, so aluminum and titanium resist corrosion. These properties make the two metals very useful.
Give some uses of Aluminum and Titanium.	- Aluminum is used for aircraft, trains, overhead power cables, saucepans and cooking foil. - Titanium is used for fighter aircraft, artificial hip joints and pipes in nuclear power stations.
Iron can be extracted, but what about Aluminum and Titanium???	Unlike iron, aluminium and titanium cannot be extracted from their oxides by reduction with carbon. Existing methods are expensive because the processes have many stages and large amounts of energy are needed.
Aluminum is recycled. WHY???	Aluminium is (extensively) recycled because less energy is needed to produce recycled aluminium than to extract aluminium from its ore. Recycling preserves limited resources and requires less energy, so it causes less damage to the environment.
Give 3 examples of alloys and why they are useful.	- brass (electrical fittings) is 70 percent copper and 30 percent zinc. - 18 carat gold (jewellery) is 75 percent gold and 25 percent copper and other metals - duralumin, (aircraft manufacture) is 96 percent aluminum and 4 percent copper and other metals.
(Pure) iron is soft and easily shaped. WHY???	Because its atoms are arranged in a regular way that lets layers of atoms slide over each other, therefore pure iron is too soft for many uses.
FINISH THIS SENTENCE: Iron from the blast furnace is an alloy of about...	Iron from the blast furnace is an alloy of about 96 percent iron, with carbon and some other impurities. It is hard; too brittle for most uses, so most iron from the blast furnace is converted into steel by removing some of the carbon.
Explain how STEEL is made.	Carbon is removed from molten iron by blowing oxygen into it. The oxygen reacts with the carbon, producing carbon monoxide and carbon dioxide, which escape from the molten metal. Enough oxygen is used to achieve steel with the desired carbon content. Other metals are often added, such as vanadium and chromium, to produce alloys with properties suited to specific uses.
FINISH THIS SENTENCE: Crude oil is a mixture of compounds called...	hydrocarbons.
What are HYDROCARBONS???	Hydrocarbons are compounds that contain hydrogen and carbon atoms only, joined together by covalent bonds.
What are ALKANES???	The alkanes are a family of SATURATED hydrocarbons that share the same formula.
What is the GENERAL FORMULA for Alkanes?	CnH2n+2 note. 2n+2 is little, just in case if it comes up in the exam.
Alkanes are unreactive. WHY???	Alkanes are saturated hydrocarbons, this means that their carbon atoms are joined to each other by single bonds. Becuase of this, they are (relatively) unreactive, apart from burning or combustion, which is (therefore) their reaction with oxygen in the air.
What is DISTILLATION???	Distillation is a process that can be used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points. Distillation is commonly used to separate ethanol (the alcohol in alcoholic drinks) from water.
Explain how water and ethanol are separated by using distillation. (1/2)	The mixture is heated in a flask. Ethanol has a lower boiling point than water so it evaporates first. The ethanol vapour is then cooled and condensed inside the condenser to form a pure liquid.
Explain how water and ethanol are separated by using distillation. (2/2)	The thermometer shows the boiling point of the pure ethanol liquid. When all the ethanol has evaporated from the solution, the temperature rises and the water evaporates.
SEQUENCE OF EVENTS IN DISTILLATION:	heating → evaporating → cooling → condensing
Explain how FRACTIONAL DISTILLATION works.	Fractional distillation is different from distillation in that it separates a mixture into a number of different parts, called fractions. A tall column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top. The crude oil is evaporated and its vapours condense at different temperatures in the fractionating column. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms.
FINISH THIS SENTENCE: As you go up the fractionating column, the hydrocarbons have...	lower boiling points, lower viscosity (they flow more easily) and higher flammability (they ignite more easily). Therefore, this means that in general hydrocarbons with small molecules make better fuels than hydrocarbons with large molecules.
What is COMBUSTION???	Combustion is a chemical reaction that involves the rapid combination of a fuel with oxygen.
FINISH THIS SENTENCE: Carbon dioxide is a greenhouse gas. Increasing concentrations of it in the atmosphere...	contribute to global warming.
Describe what happens during COMPLETE COMBUSTION.	Fuels burn when they react with oxygen in the air. If there is plenty of air, complete combustion happens. Coal is mostly carbon. During complete combustion, carbon is oxidised to carbon dioxide: carbon + oxygen → carbon dioxide
FINISH THIS SENTENCE: Hydrocarbon fuels contain carbon and hydrogen. During combustion, hydrogen is...	oxidised to water (remember that water, H2O, is an oxide of hydrogen). In general: hydrocarbon + oxygen → carbon dioxide + water
Describe what happens during INCOMPLETE COMBUSTION.	If there is insufficient air for complete combustion, incomplete combustion (also called partial combustion) happens. Hydrogen is still oxidised to water, but carbon monoxide forms instead of carbon dioxide. Carbon monoxide is a toxic gas, so adequate ventilation is important when burning fuels. Solid particles (particulates) are also released. These contain carbon and are seen as soot or smoke. Particulates cause global dimming. They reduce the amount of sunlight reaching the Earth’s surface.
Rainwater is slightly acidic. WHY???	Because carbon dioxide dissolves in water in the atmosphere to form a weakly acidic solution. Therefore, this means that rainwater is naturally slightly acidic.
FINISH THIS SENTENCE: Acid rain reacts with metals and rocks such as limestone, causing damage to buildings and statues. Acid rain damages the...	waxy layer on the leaves of trees. This makes it more difficult for trees to absorb the minerals they need for healthy growth and they may die. Acid rain also makes rivers and lakes too acidic for some aquatic life to survive.
Which gas causes ACID RAIN???	Sulfur dioxide (SO2)
FINISH THIS SENTENCE: Sulfur can be removed from fuels before they are used. ‘Low sulfur’ petrol and diesel are widely available at filling stations to use in vehicles. In power stations, ...	sulfur dioxide can be removed from the waste gases before they are released from chimneys. The waste gases are treated with powdered limestone. The sulfur dioxide reacts with it to form calcium sulfate. This can be used to make plasterboard for lining interior walls, so turning a harmful product into a useful one.
Another gas can cause acid rain. Describe?	At the high temperatures found in an engine or furnace, nitrogen and oxygen from the air can react together. They produce various oxides of nitrogen, often called NOx. This can (also) cause acid rain.
State what is meant by NON-RENEWABLE.	Something in limited supply, which cannot be replaced once it has been used up.
What are BIOFUELS?	Biofuels are fuels produced from plant material.
Give 6 harmful substances that are produced from crude oil when burnt:	- carbon dioxide - carbon monoxide (- water vapour) - particulates (solid particles) - sulfur dioxide - oxides of nitrogen or NOx.
What is BIODIESEL made of?	Biodiesel is made from rapeseed oil and other plant oils. It can be used in diesel-powered vehicles without needing any modifications to the engine.
Ethanol is NOT an alkane. WHY???	Ethanol (C2H5OH) is not a hydrocarbon because it contains oxygen as well as hydrogen and carbon.
Explain how BIOETHANOL is made.	Bioethanol is made by fermenting sugars from sugar cane, wheat and other plants. It cannot be used on its own unless the engine is modified. However, modern petrol engines can use petrol containing up to 10 percent ethanol without needing any modifications, and most petrol sold in the UK contains ethanol.
Describe 3 ethical issues with making biofuels:	- human resources -more people are needed to produce biofuels than are needed to produce petrol and diesel - increased income (for farmers) - lower fuel prices - biofuels limit the demand for fossil fuels, helping to reduce increases in fuel prices.
Explain the environmental issues of biofuels.	There are environmental issues surrounding the use of biofuels. Biodiesel naturally contains little sulfur. For example, it may be said that they are carbon neutral – the amount of carbon dioxide released when they are used is the same as the amount absorbed by the plants as they grew. If so, this would reduce the production of this greenhouse gas. However, while biofuels produce less carbon dioxide overall, they are not carbon neutral. This is because fossil fuels are used in their production, for example in making fertilisers for the growing plants.
What are ALKENES?	The alkenes are a family of UNSATURATED hydrocarbons that share the same formula.
What is the GENERAL FORMULA for alkenes?	CnH2n
What does cracking allow?	Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are heated to vaporise them. They are then either passed over a hot catalyst, or mixed with steam and heated to a very high temperature.
FINISH THIS SENTENCE: Alkenes are unsaturated hydrocarbons. They contain a...	double covalent bond, which is shown as two lines between two of the carbon atoms. The presence of this double bond allows alkenes to react in ways that alkanes cannot. They can react with oxygen in the air, so they could be used as fuels. But they are more useful than that: they can be used to make ethanol and polymers (plastics) - two crucial products in today's world.
TESTING FOR UNSATURATION!!!	Bromine water is a dilute solution of bromine, normally orange-brown in colour. It becomes colourless when shaken with an alkene, but its colour remains the same when it is shaken with alkanes.
What are POLYMERS?	Polymers are very large molecules made when many smaller molecules join together, end-to-end.
What is a SMART POLYMER???	A smart polymer is a high-performance polymers that change according to the environment they are in.
FINISH THIS SENTENCE: Alkenes can act as monomers because they are unsaturated (they have a double bond):	ethene can polymerise to form poly(ethene), also called polythene. Also, propene can polymerise to form poly(propene), also called polypropylene.
HYDROGENATION!!! (HIGHER TIER ONLY)	60 degrees, reacted with hydrogen, nickel catalyst, double bonds converted into single bonds, increasing melting point, done so that's it's a solid at room temperature for a thick, spreadable consistency.
FINISH THIS SENTENCE: Vegetable oils have higher boiling points than water. This means that...	foods can be cooked or fried at higher temperatures than they can be cooked or boiled in water. Food cooked in vegetable oils: cook faster than if they were boiled and they have different flavours than if they were boiled.
HOWEVER...	However, vegetable oils are a source of energy in the diet. Food cooked in vegetable oils releases more energy when it is eaten than food cooked in water. This can have an impact on our health. For example, people who eat a lot of fried food may become overweight.
MONOSATURATED vs POLYSATURATED!!! GO GO GO!!!	- monounsaturated fats = one double bond in each fatty acid. - polyunsaturated fats = many double bonds.
What is an EMULSION?	An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable).
FINISH THIS SENTENCE: Emulsions are thicker (more viscous) than the oil or water they contain. This makes them...	useful in foods such as salad dressings and ice cream. Emulsions are also used in cosmetics and paints.
OIL DROPLETS vs WATER DROPLETS GO GO GO!!!	- oil droplets in water (milk, ice cream, salad cream, mayonnaise) - water droplets in oil (margarine, butter, skin cream, moisturising lotion).
What are EMULSIFIERS?	Emulsifiers are substances that stabilise emulsions, stopping them separating out.
Emulsifiers - 2 different ends (HIGHER TIER ONLY)	- a hydrophilic end - 'water-loving' - that forms chemical bonds with water but not with oils - a hydrophobic end - 'water-hating' - that forms chemical bonds with oils but not with water.
Describe the hydrophilic and the hydrophobic tail.	The hydrophilic 'head' dissolves in the water and the hydrophobic 'tail' dissolves in the oil. In this way, the water and oil droplets become unable to separate out.
BROMINE WATER TEST #2!!!	Unsaturated vegetable oils contain double carbon-carbon bonds. These can be detected using bromine water (just as alkenes can be detected). Bromine water becomes colourless when shaken with an unsaturated vegetable oil, but it stays orange-brown when shaken with a saturated vegetable fat. Bromine water can also be used to determine the amount of unsaturation of a vegetable oil. The more unsaturated a vegetable oil is, the more bromine water it can decolourise.
STRUCTURE OF THE EARTH!!! a little message to all of you GCSE geography students - this is a breeze for us!!!	Image: Structur Eof The Earth (image/gif)
FINISH THIS SENTENCE: The Earth's crust and upper part of the mantle are broken into large pieces called tectonic plates. These are constantly moving at...	a few centimetres each year. Although this doesn't sound like very much, over millions of years the movement allows whole continents to shift thousands of kilometres apart. This process is called continental drift.
The plates move. WHY???	The plates move because of convection currents in the Earth’s mantle. These are driven by the heat produced by the natural decay of radioactive elements in the Earth.
WEGNERboiiiiiiii #wegnerisbae	Wegener suggested that mountains were formed when the edge of a drifting continent collided with another, causing it to crumple and fold. For example, the Himalayas were formed when India came into contact with Asia. It took more than 50 years for Wegener’s theory to be accepted. One of the reasons was that it was difficult to work out how whole continents could move: it was not until the 1960s that enough evidence was discovered to support the theory fully.
CONTINENTIAL vs OCEANIC!!! GO GO GO!!! more GCSE geography revision weyyyy	- Oceanic plates occur under the oceans. -Continental plates form the land. Oceanic plates are denser than continental plates. They are pushed down underneath continental plates if they meet.
GASES IN DA ATMOSPHERE!!!	Image: C0f067f1fda49b3a61d31d9d53b5d11b00c6dd18 (image/gif)
Miller-Urey experiment (HIGHER TIER ONLY) (1/2)	Sealed a mixture of water, ammonia, methane and hydrogen in a sterile flask. The mixture was heated to evaporate water to produce water vapour.
Miller-Urey experiment (HIGHER TIER ONLY) (2/2)	Electric sparks were passed through the mixture of water vapour and gases, simulating lightning. After a week, contents were analysed. Amino acids, the building blocks for proteins, were found.
FINISH THIS SENTENCE: The Miller-Urey experiment supported the theory of a...	‘primordial soup’, the idea that complex chemicals needed for living things to develop could be produced naturally on the early Earth.
INCREASING OXYGEN!!!	Plants and algae can carry out photosynthesis. This process uses carbon dioxide from the atmosphere (with water and sunlight) to produce oxygen (and glucose). The appearance of plants and algae caused the production of oxygen, which is why the proportion of oxygen went up.
DECREASING CARBON DIOXIDE!!!	hotosynthesis by plants and algae used carbon dioxide from the atmosphere, but this is not the only reason why the proportion of carbon dioxide went down. These processes also absorb carbon dioxide from the atmosphere: dissolving in the oceans, the production of sedimentary and rocks such as limestone the production of fossil fuels from the remains of dead plants and animals.
Liquefying air (HIGHER TIER ONLY)	- water vapour condenses, and is removed using absorbent filters - carbon dioxide freezes at –79ºC, and is removed - oxygen liquefies at –183ºC - nitrogen liquefies at –196ºC.
Liquefying air (HIGHER TIER ONLY) = LONG ANSWERRRRRRR	The liquid nitrogen boils at the bottom of the column. Gaseous nitrogen rises to the top, where it is piped off and stored. Liquid oxygen collects at the bottom of the column. The boiling point of argon - the noble gas that forms 0.9 percent of the air - is close to the boiling point of oxygen, so a second fractionating column is often used to separate the argon from the oxygen.
USES OF NITORGEN AND OXYGENNNN	- liquid nitrogen is used to freeze food. - food is packaged in gaseous nitrogen to increase its shelf life. - oil tankers are flushed with gaseous. - nitrogen to reduce the chance of explosion - oxygen is used in the manufacture of steel and in medicine.

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