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77 Cards in this Set
- Front
- Back
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What are all substances made up of? |
Atoms - Substances that contain just one type of atom is called an element. |
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In the periodic table, what are the vertical columns called and what do they show?
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Groups, elements in groups all have similar properties. |
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What is at the centre of an atom and what is the centre made up of? |
At the centre of an atom there is a nucleus, and this nucleus is made up of protons and neutrons. |
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What is on the outside of a nucleus in an atom? |
On the outside of the nucleus there are electrons. |
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True or false: The number of protons is the same as the number of electrons. This means that the atoms have no overall charge. |
True! |
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True or false: The number of neutrons in an atom of an element is the atomic number. |
False!
The amount of PROTONS in an atom of an element is the atomic number.
An example: Sodium (Na) has 11 protons, so its atomic number is 11. |
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How do you calculate the mass number of an atom? |
The sum of the number of protons and neutrons in an atom is its mass number.
An example: In a sodium atom there are 11 protons and 12 neutrons. This means that the mass number of this sodium atom is 11+12=23. |
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How are electrons arranged? |
Electrons are arranged in energy levels. Electrons fill the lowest energy level first. Energy levels are also called shells. |
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What do elements in the same group have in common, in terms of energy shells? |
Elements in the same group have the same amount electrons in the outer shell. |
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What is a compound? |
A compound is a substance made up of two or more elements. Compounds are produced in chemical reactions. |
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What are ionic bonds? |
Ionic bonds are compounds where the positive and negative ions are strongly attracted to each other. The forces of attraction between positive and negative ions are called ionic bonds.
Ionic bonds only exist in compounds made up of metals and not metals. |
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What are covalent bonds? |
Covalent bonds consist of two non-metal elements.
An example: Carbon dioxide, it is made up of two non-metals. so cannot contain ionic bonding because there are no metal ions to give away electrons. Instead, its atoms are joined together in groups of three. Each atom has one carbon and two oxygen atoms. |
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Give an example of a word equation for a chemical reactions. |
Magnesium + Oxygen → Magnesium oxide
For Higher students, you should write the symbol equation: Mg + O₂ → 2MgO
There needs to be a '2' in front of the product so the equation is balanced. |
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Are atoms lost or made in a reaction? |
Neither, the reactants need to be the equal to the mass of the products.
For example, reacting 48g of magnesium with 32g of oxygen produces (48+32) = 80g of magnesium oxide. |
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What is limestone and what are some of its properties? |
Limestone is a type of rock, and its mainly calcium carbonate, CaCO³⁻.
>Mixing cement with sand makes mortar. Builders use this ti stick bricks together >Mixing cement with sand and aggregate makes concrete |
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Name an environmental, social, and economic advantage of quarrying. |
Environmental - Old quarries can be made into lakes.
Social - Quarries provide jobs and limestone to make buildings.
Economic - Quarry companies sell the limestone. |
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Name an environmental, social, and economic disadvantage of quarrying. |
Environmental - Quarries make land unavailable for other purposes, such as farming.
Social - Quarries create extra traffic.
Economic - Tourists may stop visiting an area with a new quarry. |
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What is an ore? |
An ore is a rock from which a metal can be extracted. This process can be expensive and the companies extracting the metal need to consider how much they can sell the metal for before extracting.
Factors can change overtime, which can show an increase and decrease in the demand for some metal. |
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How are ores processed? |
Companies dig metal ores from the ground. This is mining. The ore is then concentrated to separate its metal compounds from waste rock. Next, the metal is extracted form its compounds, and purified. |
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How is iron extracted? |
Iron is extracted from is oxide in a blast furnace:
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How is aluminium extracted? |
Aluminium is extracted by electrolysis. Electricity passes through liquid aluminium oxide. The aluminium oxide breaks down and:
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How are copper-rich ores extracted? |
Companies heat copper-rich ores in a furnace. Chemical reactions remove other elements from the copper compounds in the ore. This is smelting. |
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How is copper from low-grade ore extracted? |
Copper-rich ores are running out. So companies now extract copper by smelting low-grade ores that contain less copper. The is expensive, but the high demand for copper means companies can still make a profit. Extracting copper form low-grade ores produces huge amounts of waste. This damages the environment. |
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What is phytomining? |
This is a way of extracting copper from low-grade ores. This technique causes less damage to the environment.
This involves planting certain plants on low-grade copper ores. The plants absorb copper compounds. Burning the plants produces an ash that is rich in copper compounds. |
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What is bioleaching? |
This is another way of extracting copper form low-grade ores. This also causes less damage to the environment.
This uses bacteria to produce solutions of copper compounds. Copper metal is extracted form these solutions by chemical reactions or electrolysis. |
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Why is it good to recycle metals? |
Recycling scrap metal involves and making it into new things. This is encouraged because:
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State the two ways pure copper is extracted from recycled copper. (involves copper salts) |
One method of obtaining pure copper from scrap copper involves making solutions of copper salts.
Electrolysis - positive copper ions move towards the negative electrode. Here, they gain electrons to form copper atoms.
Displacement - scrap iron is added to the solution. Iron is more reactive that copper, so it displaces copper from its compounds. |
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What is iron from a blast furnace mixed with to make it cast iron? |
Iron from the blast furnace contains 96% iron and 4% impurities. This makes it brittle and breaks if you drop it, which means it has few uses.
Some blast furnace iron is re-melted and mixed with scrap steel. This make cast iron. |
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What is steel mixed with to make is more useful? |
Steel is mainly iron, so it is mixed with carbon and other metals to change its properties and make it more useful. |
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What is an alloy? |
An alloy is a mixture of metal with one or more other elements. Steel is an example of this. |
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What do copper, gold, iron, and aluminium need to be mixed with to make them more useful. |
The mentioned metals are too soft for many uses, so they are mixed with small amounts of similar metals to make alloys. This allows them to be harder and more useful. |
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What is crude oil and what is the main compound in it? |
Crude oil is a fossil fuel. It was formed from the decay of buried dead sea creatures over millions of years.
Crude oil contains any different compounds. Many of the compounds are hydrocarbons. Hydrocarbons are made up of carbon and hydrogen only. |
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What is a mixture? |
A mixture consists of two or more elements or compounds that are not chemically combined together. In a mixture:
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What is fractional distillations? |
Crude oil is not as useful as it is. But separating it into fractions make valuable fuels and raw material. A fraction is a mixture of hydrocarbons whose molecules have similar number of carbon atoms.
Oil companies use the property of boiling to separate crude oil into fractions by fractional distillation. |
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How does fractional distillation work? |
Fractional distillation involves these steps:
> Compounds with the highest boiling points condenses at the bottom to the column, and leaves as liquids. > Lower-boiling-point compounds condense higher up, where it is cooler, and leave as liquids. > The lowest-boiling-point compounds leave from the top, as gases. |
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Size of hydrocarbon fuels |
Hydrocarbon properties depend on their molecule size. These properties influence how hydrocarbons are used as fuels.
> 1 to 4 carbon atoms means this will be gas at room temperature > 5-16 means liquid at room temperature > 17+ means solid at room temperature |
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Burning hydrocarbon fuels |
The combustion (burning) of fuels releases energy. During combustion, carbon and hydrogen atoms from fuels join with oxygen from the air. The carbon and hydrogen are oxidised.
Burning hydrocarbon produces two main products - carbon dioxide and water vapour. |
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What are fossil fuels? |
Fossil fuels are finite resources that have been formed over millions of years. They will not last for ever.
Fossil fuels include, crude oil, natural gas, and coal. |
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What are biofuels? |
Biofuels are fuels made from substances obtained form living things. Ethanol can be made from sugar cane. Biodiesel is made from plant oils such as sunflower oil. |
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Name an advantage and disadvantage of economic issues related to biofuels. |
ADV: Biofuels producers sell their products.
DIS: Converting filling stations to dispense biofuels is expensive. |
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Name an advantage and disadvantage of social and ethical issues related to biofuels. |
ADV: Biofuels are renewable, so using them does not take supplies from future generations.
DIS: Fuel crops may be grown on land that some people think should be used to grow food. |
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Name an advantage and disadvantage of environmental issues related to biofuels. |
ADV: The plants from which biofuels are made remove carbon dioxide from the atmosphere as they grow.
DIS: More carbon dioxide is produced than removed, as the farm machinery in the production of the fuel produces a lot of carbon dioxide. |
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What is a benefit and a hazard of hydrogen fuel? |
Hydrogen fuel can be used as vehicle fuel. It ignites easily, and produces just one product on burning - water vapour.
Hydrogen is explosive when mixed with air, so it is difficult to store and transport safely.
Hydrogen fuel can be made from methane gas, which is a renewable source. |
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Why are some hydrocarbon fractions cracked? |
Hydrocarbon fractions are cracked to make smaller, more useful molecules to meet the high demand of required resources such as petrol and oil. |
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What is the process of cracking? |
Cracking involves heating hydrocarbons to vapourise then. THe vapours can then be:
Under these conditions hydrocarbons molecules in the vapour mixture break down to form smaller molecules in thermal decomposition reactions. The catalyst speeds up thermal decomposition reactions but is not itself used up. |
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Example of cracking: What does cracking octane produce? |
Cracking naphtha to produce octane can then mean that the octane fraction can be broken down to make two smaller molecules which are hexane and ethane.
Hexane is a useful fuel. It is added to the petrol fractions. |
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What is an example of an unsaturated hydrocarbon? |
An unsaturated hydrocarbon means that there is a double bond. An example is ethene, this has a double bond which means there are two carbon atoms. |
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How can you detect alkenes? (Hint: Bromine) |
You can detect unsaturated compounds by testing with bromine water.Orange bromine water becomes colourless when it reacts with alkenes.
When saying this in a test, you must use the keyword colourless to get the marks. |
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What are polymers and how are they made? |
Alkanes are important raw materials. They are used to make polymers. Polymers are materials that have very big molecules. They are made by joining together many small molecules, called monomers. |
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Polymer properties |
There are thousand of different polymers. Each has unique properties. The uses of a polymer depend on its properties. Scientists continue to develop new polymers.
For example:
Polymer properties make some better than others. |
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How are polymers disposed? |
Many polymers are non-biodegradable - they cannot be broken down by microbes. This created disposal problems because when they are put into landfill sites, they remain unchanged for many years.
Chemists are developing new ways for solving this problem:
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Name an advantage and disadvantage of environmental affects of cornstarch and maize in polymers. |
ADV: Biodegradable
DIS: Fertilisers used to help maize grow may pollute rivers and lakes. |
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Name an advantage and disadvantage of Economic affects of cornstarch and maize in polymers. |
ADV: Growers and manufacturers have products to sell.
DIS: Cornstarch nags can be more expensive than other poly(ethene) ones. |
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Name an advantage and disadvantage of Social and economic affects of cornstarch and maize in polymers. |
ADV: Cornstarch is renewable, so using it to make bags does not take supplies form future generations.
DIS: Grown in land that could be used for crops. |
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Name three uses of ethanol. |
Ethanol can be used for:
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What are the two ways that ethanol can be made? |
Ethanol from ethane
In this method, ethene reacts with stem in the presence of the catalyst. Ethanol is the product of this hydration reactions.
ethene + steam → ethanol C₂H₄ + H₂O → C₂H₅OH
This reaction works best at 300'C
Ethanol from sugars
Ethanol can also be produced by fermentation. In fermentation, enzymes in yeast breaks down plant sugars into ethanol and carbon dioxide. For example: Glucose → ethanol + carbon dioxide
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Name the advantages and disadvantages of the two processes to make ethanol. |
For raw materials: Hydration - ethene is produced from crude oil, which is non-renewable. Fermentation - Plant materials are renewable.
For energy costs: Hydration - Higher - both the cracking to produce ethene, and the hydration reaction take place at high temperatures. Fermentation - Lower - fermentation takes place at a lower temperature but the crops may require input such as fertiliser. |
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How are vegetable oils extracted? |
Oils are extracted from different plants in different ways:
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What are the advantages of vegetable oils? |
Vegetable oils are important foods. They provide nutrient, such as vitamin E. They also release a lot of energy when digested.
Vegetable oils boil at higher temperatures than water. So oils can cook foods at a higher temperature than boiling water. This means that:
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What are unsaturated oils? |
Sunflower oils is unsaturated. It contains double bonds between some of the carbon atoms in the molecules. You can represent a carbon-carbon atoms like this C=C. |
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What are saturated oils? |
Coconut oil is saturated. Its molecules do not have double bonds between their carbon atoms. Saturated fats raise blood cholesterol and increased the risk of heart disease. Unsaturated fats are better for health. |
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What are the four layers of the earth? |
The four layers of the earth, in order from inside to out, are:
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What are the mixture of gases surrounding the earth? |
The mixture of gases surrounding the earth are called the atmosphere. |
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What are tectonic plates and how do they move? |
The earth's crust and upper part of the mantle are cracked in to approximately 12 huge pieces, these are called tectonic plates.
The plates are less dense that the part of the mantle below them. The mantle is solid but can move slowly.
Deep inside the earth, natural radioactive processes heat the mantle. he heat drives convection currents within the mantle. The convection currents make tectonic plates. They move slowly, at relative speeds of a few centimetres a year. |
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Where do volcanoes occur? |
Many volcanoes are at tectonic plate boundaries. Volcanoes often show signs of eruption in advanced but the timing of an eruption depends on many factors. It is difficult to predict eruptions exactly.
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Why do earthquakes happen? |
Earthquakes happen when tectonic plates move against each other suddenly. Scientists cannot predict when these movements will happen, so people living on plate boundaries can expect an earthquake at any time. |
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What was Wegener's theory? |
In 1912, Wegener put forward a new theory to explain the features of the earth. He suggested that the continents were once joined together, and had gradually moved apart. Wegener supported his theory with evidence.
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Why did scientists not accept Wegener's theory? |
At this time, most scientists did not accept Wegener's theory of crustal movement, or continental drift. This was because:
Since the 1950s, scientists have discovered more evidence supporting wegeners theory. Now his ideas are generally accepted. |
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What are the main gases in the atmosphere? |
The two main gases are Nitrogen (80%) and Oxygen (20%). |
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What was the primordial soup theory? |
Because no one was around at the time, there was no one to make observations about the origin of life. There are several scientific theories to explain it, one of them was: The primordial soup theory involves the interaction between:
According to the theory, gases in the early atmosphere reacted with each other in the presence of lightning, or sunlight, to make the complex molecules that are the basis of life. |
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What formed the earths early atmosphere? |
The gases from volcanic eruptions formed the early atmosphere. Water vapour from the eruptions condensed to form the oceans.
There are several theories about how the atmosphere formed. |
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What were the gases in the early atmosphere? |
The main gas in the early atmosphere was carbon dioxide. Although, there were small amounts of water vapour, methane, and ammonia. |
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What is the Miller-Urey experiment and how does it work? |
The Miller-Urey experiment created to test the Primordial soup theory. It simulated a lightning spark in a mixture of gases of the early atmosphere. A week later, more than 2% of the carbon in the system had formed compounds from which the proteins in living cells are made. |
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Where did the oxygen in the early atmosphere come from? |
Plants make their food by photosynthesis. They take carbon dioxide from the atmosphere and release oxygen gas.
carbon dioxide + water → glucose + oxygen
The photosynthesis of early plants and algae removed carbon dioxide from the atmosphere, and added oxygen gas. |
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What happened to the carbon dioxide that was not used in photosynthesis? (Hint: Locked) |
Some of the carbon dioxide from the early atmosphere was removed by plants. But not all of it.
Locking up carbon in rocks: Much carbon dioxide dissolved in the ocean. Shellfish and other sea creatures used some of this dissolved carbon dioxide in making their shells and skeletons. The animals died and fell to the bottom of the sea. After many years, limestone, a sedimentary rock, formed from their shells and skeletons. The carbon atoms were locked away in the calcium carbonate.
Locking up carbon in fossil fuels: Millions of years ago, dead animals and plants decayed under swamps. The dead organisms formed fossil fuels. The carbon atoms of the plants and ammonia were locked up in underground stored of coal, oil, and gas. |
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What happens to the extra carbon dioxide in the atmosphere which hasn't been used by plants for photosynthesis? |
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Why is it good that gases in the air have different boiling points? |
The gases in the air have different boiling points. This means that the gases can be separated by fractional distillation. The fractional distillation of air provides:
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