Chemistry 1 key term flashcards

Element
Substance made of only 1 type of atom which cannot be broken down into any simpler substance
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Atom
Smallest part of an element which is still recognisible as that element
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Chemical symbol
How elements are represented e.g. Na = sodium, Cl = chlorine. 1 chemical symbol represents 1 atom of the element
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Periodic group facts
Column of the periodic table. Elements in the same group have the same number of electrons in the outer energy level, because of this they have similar properties
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Why are elements near the bottom of a periodic group more reactive than those towards the top?
More electrons means outer shell further from the nucleus have a weaker electrostatic force
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Electrostatic force
Force that attacts the electrons to the nucleus
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Compound
Substance made of atoms from more than 1 element
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Mixture
Many elements in one place mixed up which do not react or bond together, not a pure substance
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Why does an atom have no overall charge?
The number of positive protons and negative electrons is equal, meaning the charges are equal and opposite so balance out
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Atomic number
The number of protons of the element (for an atom but not an ion, this is also the number of electrons)
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Mass number
Total number of particles in the nucleus (protons plus neutrons)
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Energy level
Area surrounding the nucleus where electrons are found
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Electronic structure
The arrangement of electrons, how many is in each energy level of an atom
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Describe what happens when a metal reacts with non-metal
Ions are formed, metals always LOSE electrons, non-metals always GAIN. The ions attract, this is an ionic bond.
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Ionic bond
Metal and non-metal. Electrons are taken, not shared.
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Chemical formula
Expression stating number and type of atoms present in a substance, e.g. NaCl
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What does a chemical formula for an ionic bond tell you
The simplest RATIO of ions in the substance
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What does a chemical formula for a covalent bond tell you
The NUMBER of atoms in the molecule
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Describe what happens when a non-metal and a non-metal react
The electrons are shared between the atoms, this keeps them together in a covalent bond.
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Reactants
Substances on the left hand side of the equation which are rearranged to form the products
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Products
Substances on the right hand side of the equation. In reversible reactions these can rearrange back to form the reactants
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Word equation
States the reactants and products in a reaction
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Symbol equation
Gives number and types of atoms in a reaction. Must always be balanced (same amount of each type of atom on each side)
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What makes up limestone?
Mostly Calcium Carbonate (CaCO3)
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What do all metal carbonates break decompose into?
The metal oxide + carbon dioxide
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If any metal carbonate reacts with an acid what are the products?
A salt, water and carbon dioxide (the salt is whatever is left over when the water and carbon dioxide have been produced) e.g. MgCO3 + 2 HCl = MgCl2 + CO2 + H2O
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What does the limewater test check for, and how does it work?
Tests for CO2. CO2 reacts with the calcium hydroxide to produce calcium carbonate, which is insoluble in water. If CO2 is present the limewater will turn cloudy
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What is "limewater"?
Ca(OH)2 - calcium hydroxide solution
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Cement
(powdered) limestone mixed with (powdered) clay, then heated in kiln
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Mortar
Cement plus sand and water (used in between bricks)
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Concrete
Mortar plus aggregate (rock pieces) used as a building material
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Ore
Rock containing enough metal (often metal containing compounds) to make it worth extrating
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Displacement of oxygen by Reduction
Using a more reactive element (usually carbon) to remove the oxides from a metal compound
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Blast furnace
Reaction vessel where iron is extracted from its ore to make cast iron
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Problems with Iron that mean alloys are needed
Cast iron (96% iron) brittle and hard due to impurities, so has few uses. Pure iron too soft for most uses.
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Aluminium notes (compare to titanium)
Found as aluminium oxide, Low density, non-corrosive, more reactive than carbon (cannot be reduced), extracted by expensive + high energy/heat demanding electrolysis, expensive to extract, not strong when pure so used as alloy, quite fast extraction
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Titanium notes (compare to aluminium)
Found as titanium oxide, Quite low density, non-corrosive, less reactive than carbon (could be reduced) but not as it ruins its properties, numerous costly stages to extract, very strong, expensive extraction, takes longer to extract
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Properties of low carbon steel (an iron alloy)
Softer, easy to shape (used in car bodies and wires)
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Properties of high carbon steel (an iron alloy)
Harder and stronger, but brittle (used in cutting tools and nails)
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Smelting of copper
Extracting copper from copper-rich (high grade only) ore by heating in a furnace, produces impure copper. Requires lots of energy
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Electrolysis of copper
Used to purify copper in solution after smelting, requires high temperatures and energy
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Phytomining
Plants grown above low grade copper ores, they absorb copper from the ground, when burnt the ash contains copper that can be extracted
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Bioleaching
Using bacteria to absorb copper compounds from low grade ores to produce solutions containing copper compounds
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Properties of Transition Metals
Strong, malleable (as layers of atoms of the same size can slide over each other easily), conduct heat, conduct electricity, do not react with water
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Why are alloys stronger than most elements alone?
Alloys have different sized atoms which distorts the regular arrangement, meaning it is harder for layers to slide over each other so atoms stay in place
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Why is recycling metals important?
Means less ore needs to be mined, reducing pollution. Less fossil fuels needed to provide energy for the extraction of metals from their oxides
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Crude oil
Mostly made of hydrocarbons of different lengths with different boiling points, few uses as crude oil, separating provides useful fuels
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Fractions
Liquids that boil between different temperature ranges
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Alkanes
Have a general formula of CnH2n+2. Saturated hydrocarbons
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General Formula meaning
Formula of how to work out the number of each type of atom in the substance. "General" means it can be used to find this for a series of related substances, such as any alkanes rather than just for methane
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Molecular Formula meaning
Formula showing the number and type of atoms in 1 molecule of a substance, specific to that molecule (e.g. molecular formula of methane and ethane are different despite both being alkanes)
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Display Formula meaning
Drawing. Shows how the atoms are bonded together
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Functional Group meaning
The group of atoms which are responsible for the characteristic reactions of a particular compound. E.g. for alcohols the functional group is the -OH, without this it would not react in the same way.
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The stages of fractional distillation
Crude oil vaporised, fed into fractionating column, move up column as a gas, condense when they reach their BP, collect at tray just below along with other similar sized hydrocarbons, outlets collect each fraction.
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Properties of low boiling point fractions
Low viscosity (runny), flammable so easy to ignite (useful as fuels), burn with clean flames (little smoke)
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Complete combustion of hydrocarbons
Oxidized to produce carbon dioxide and water (complete combustion is rare, as the hydrocarbon must be completely pure for this to happen)
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Incomplete combustion of hydrocarbons
Happens in limited air supply. Can produce carbon monoxide (poisonous), solid particles of soot (carbon), unburnt hydrocarbons called particulates
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Problems with burning fossil fuels
Most contain sulfur compounds, burning them produce sulfur dioxide. At the high temps when burning oxygen and nitrogen in the air may combine giving nitrogen oxides, both = acid rain. Carbon dioxide traps sunlight in atmosphere adds to global warming
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Global dimming
Tiny solid particulates reflect the sunlight
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Methods of removing harmful substances from waste gases to reduce environmental effects
Sulfur dioxide removed from power station waste before release. Catalytic converters in car exhaust systems remove CO and nitrogen oxides. Filters remove particulates, sulfur removed from fuels before supplying so less sulfur dioxide produced
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Biofuels and Biodiesel
Biofuels are made from plant / animal waste so are renewable. Biodiesel is made from vegetable oils extracted from plants so is also renewable
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Advantages of biofuels
Carbon neutral (carbon emitted when burn was recently taken in by the plants as they grew), can be mixed with petrol, sustainable as it is renewable, bio-fuel refineries emit less carbon dioxide than oil refineries
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Disadvantages
Plants grown for biofuels take up large areas of farmland, grow slowly, failed crops could have huge impact on transport, poorer countires may grow less food crops as growing biofuel crops pays better which could cause hunger
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Hydrogen as a fuel
+ve: only produces water when burnt (no pollution), gas state means it takes up a large volume so is difficult to store in cars, the hydrogen can be produced by electrolysis but this takes lots of energy
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Cracking (thermal decomposition of hydrocarbons)
Breaking large hydrocarbon molecules into several smaller (more useful and in demand) ones. Method 1) heat mixture of hydrocarbon vapours and STEAM to very high temperatures. Method 2) Pass hydrocarbon vapours over hot CATALYST
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Bromine water test
AlkEnes are unsaturated ans have double bonds between carbons, so are more reactive than alkanes. Turn bromine water from orange to colourless by reacting with it
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Polymers
Very large molecules used to make plastics, made from many small monomers joined together by a polymerisation reaction. Can only be done with alkEnes as they have a double bond which can be broken
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Polymerisation reaction
Double bond monomer n C=C breaks to give single bond, meaning monomers can join together in long chains (-C-C-)n
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Smart Polymers - medical uses
Hydrogels: trap water (used for wound dressings + nappies) Light-sensitive: set under some lights (used in fillings + to seal plasters in a way that can be easily removed again) Shape-memory: change when heated (used to seal stitches using body temp)
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Smart Polymers - non-medical uses
Coat fabrics to make them waterproof, made into bottles/clothing/bedding after recycling, packaging, water-holding composts
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Problems with polymers (plastic waste)
Non-biodegradable, not broken down in the environment so wildlife harmed and unattractive rubbish build up, it takes up landfill space, many plastics means sorting is difficult + timeconsuming so some biodegradable plastics are not recycled
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Using cornstarch to reduce polymer waste
1) Make the plastics from plant materials so they biodegrade (e.g. cornstarch polymers in food packaging) 2) Mix cornstarch into non-biodegradable plastics so microbes can break them into very small pieces
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Producing Ethanol - Fermentation method
Raw material=Carbohydrate. sugar -> ethanol + CO2. uses enzymes in yeast. Requires anaerobic conditions + 30-40 degree temps. Makes dilute impure ethanol, needs distillation.Slow reaction.Renewable.Batch process, labour intensive. Cheap raw material
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Producing Ethanol - Hydration of Ethene method
Raw material=Crude oil. Ethene+steam->ethanol.Uses high pressure(60-70atm),concentrated phosphoric acid catalyst,300 degree temp(expensive conditions).Produces pure ethanol(better yield).Fast reaction,non-renewable.Continuous process, low labour cost
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Methods of extracting vegetable oils
1) Crush/ press plant material then remove water and impurities 2) Distilling plant material mixed with water, producing water and oil which can be separated due to different densities and purified
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Properties of vegetable oils
Unsaturated C=C hydrocarbon bonds (polyunsaturated - considered healthier than animal fats). High energy (useful as foods and biofuels). Can be detected via the bromine water test
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Hydrogenation reaction of vegetable oils
Makes some of all of the C=C double bonds single bonds by reacting with hydrogen. Done at 60 degrees with a nickle catalyst. Hydrogenated oils have higher BP's as more saturated, AKA hardening as the products are solid at room temperature
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Cooking with vegetable oils rather than water
Vegetable oil BP's higher than waters so food cooked at higher temperatures in oil, so cooking food is quicker as chemical reactions speed up + more collisions.Some oil is absorbed, increasing energy content.Changes texture, taste + colour of food
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Emulsions
Oil and water don't mix and separate out (due to different densities) forming layers. Shake/stir/beat together makes tiny droplets which are slow to separate, an emulsion.
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Uses of emulsions
Unique qualities: opaque and thicker than the oil and water they are made from which improves their texture, appearance and ability to stick and coat solids. Found in milk, cream / ice-cream, salad dressings, water based paint and cosmetic creams
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Emulsifiers
Substances that prevent oil and water separating out by preventing them joining, keeps emulsions stable. Emulsifier molecules have hydrophilic head and hydrophobic tail, means water and oil not in contact
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Benefits and issues of using vegetable oils and emulsifiers in foods
V.O: +ves: important nutrients, high energy, unsatfats better for health -ves: Hydrogenated VO contain satfat, linked to heart disease.Emulsifiers:+ves: smooth, creamy food (sell well)-ves: taste better so less obvious high in fat, likely to eat more
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Movement of the Earth's crust
Tectonic plates on the crust move a few mm a year due to convection currents. Convection currents are caused by radioactive decay releasing energy in the mantle, warming some parts which rise to the crust while cold denser parts sink
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Continental drift evidence
Fossils of non-aquatic/flying animals found in countries separated by oceans, some continents (S.A + Africa) look like they would fit together like a jigsaw, modern species found in different continents with common ancestor that couldn't swim/fly
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Earth's atmosphere and gases in the past
4.5Byrs ago: volcanoes covered Earth, gave out mostly CO2, some N + water vapour that condensed as Earth cooled to form oceans. 3.5 - 1.5Byrs ago: algae and plants so CO2 decreased, O increased
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Locking up carbon dioxide
Plants die + animals eat plants + die, this carbon locked up in sedimentary rocks/fossil fuels. Limestone formed from shells/skeletons of marine creatures. CO2 dissolves into oceans, some forms insoluble carbonate compounds (deposited -> SM rocks)
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Gases in the atmosphere today + separation of gases in the air
Stable. Nitrogen 78%,Oxygen 21%,Argon 0.9%,CO2 0.04%.Can be separated using fractional distillation, air cooled to -200%, Nitrogen has lower BP so out at top, Oxygen has higher BP so out at the bottom. Useful as produces pure oxygen + liquid nitrogen
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Life on Earth
Unsure how simplest living things formed, not enough evidence. Miller-Urey experiment: water, ammonia, methane + hydrogen (simulate possible early atmosphere) + high voltage spark (for lightening), week later amino acids seen (which make proteins)
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Primordial Soup - theory of how life on Earth began
Suggest a mixture of organic molecules mixed and that amino acids in the mixture combined to for proteins from which life began.
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Carbon dioxide cycle key points
CO2 in atmosphere changes as plants (respiration/photosynthesis/death), animals (feeding, growth/respiration/death), oceans and rocks (sedimentation) may store some from a time, used to be balanced but burning fossil fuels has meant an increase
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Other cards in this set

Card 2

Front

Smallest part of an element which is still recognisible as that element

Back

Atom

Card 3

Front

How elements are represented e.g. Na = sodium, Cl = chlorine. 1 chemical symbol represents 1 atom of the element

Back

Preview of the back of card 3

Card 4

Front

Column of the periodic table. Elements in the same group have the same number of electrons in the outer energy level, because of this they have similar properties

Back

Preview of the back of card 4

Card 5

Front

More electrons means outer shell further from the nucleus have a weaker electrostatic force

Back

Preview of the back of card 5
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