1. Chemistry 4
1.1. The periodic table
1.1.1. There have been many suggestions for the periodic table but the one that we use today is based of of a Russian scientist, Mendeleev's suggestion
1.1.2. The periodic table currently has 118 confirmed elements.
1.1.3. The periodic table is organised into groups based on their properties.
1.1.4. The periodic table shows details of every element including the relative atomic mass (mass number)
1.2. Alkali metals
1.2.1. They react with water to form alkaline solutions.
1.2.2. They are very reactive.
1.2.3. They are all very similar, yet none of them identical. They follow trends.
1.2.4. Lower down group one their melting points and boiling points decrease.
1.2.5. They tend to have low density.
1.3. Chemical equations
1.4. The Halogens
1.4.1. They are very reactive non-metals.
1.4.2. Group seven are called the halogens.
1.4.3. The Halogens are all very dangerous.
1.4.4. When working with the halogens you must wear eye protection as they are all toxic gases
1.5. The discovery of Helium
1.5.1. There is a spectrum of flame to tell what compound is being burnt.
1.5.2. Robert Bunson was the person who discovered the different colours nof flames being produces.
1.5.3. There are different flames for different compounds.
1.5.3.1. Green - Barium Compoud
1.5.3.2. Orange/red - Calcium compound
1.5.3.3. Lilac - Pottasium
1.5.3.4. Yellow - Sodium comound
1.6. Atomic structure
1.6.1. The structure of an atom is made up of a tiny nucleus that is what controls the goings on in the atom
1.6.2. It also has electron cloud that surrounds it, one particular electron can never be pinpointed at one time.
1.7. Electrons in atoms
1.7.1. Electrons are in an electron cloud that surrounds the nucleus, they move around quickly meaning that they can not be pin pointed.
1.8. Salts
2. Chemistry 5
2.1. Chemicals in spheres
2.1.1. There are three main parts of the earth
2.1.1.1. Lithosphere
2.1.1.1.1. It is the most inner sphere
2.1.1.1.2. Contains all of the rocks/minerals that we find
2.1.1.1.3. The lithosphere is made up of plates that are like puzzle pieces, these plates are called tectonic plates.
2.1.1.1.4. It is about 100km thick, varying in places
2.1.1.1.5. It is being used up for people to make things
2.1.1.2. Hydrosphere
2.1.1.2.1. Is the body of water contained on the earth
2.1.1.2.2. Is in between the Lithosphere and Hydrosphere
2.1.1.2.3. It is not a complete sphere but it takes up 2/3 of the world, so it alnmost is.
2.1.1.2.4. All water stays within the hydrosphere, it never escapes
2.1.1.3. Atmosphere
2.1.1.3.1. The atmosphere is where all of the gases are held inside of our earth
2.1.1.3.2. Is the most outer sphere.
2.1.1.3.3. It is much thinner in proportion to the mantle and core.
2.1.2. This is only a theory, People who study the earth "think" that the earth is made up of spheres.
2.1.3. Chemicals do not always stay in one sphere. They pass freely from one to another
2.1.3.1. Water is a good example of this, it is in most spheres.
2.1.3.2. Think of water in the hydrosphere, then clouds in the atmosphere and inside rocks in the lithosphere.
2.1.4. Water is a good example of this, it is in most spheres.
2.1.5. Water is a good example of this, it is in most spheres.
2.1.6. Water is a good example of this, it is in most spheres.
2.1.7. Chemicals do not always stay in one sphere. They pass freely from one to another
2.2. Chemicals of the atmosphere
2.2.1. The earth is ust the right soize for its gravitational pull to hold on to the atmosphere.
2.2.2. Earth is just the right distance from the sun for water to exist as a liquid, too far and it would be ice, too close and it would end up being a gas
2.2.3. The agerage temperature of the atmosphere at the earths surface is 15ºC
2.2.4. All chemicals from the atmosphere are non-metallic or non-metallic compounds.
2.2.5. Most of the atoms in the air are made up of small molecules.
2.2.6. The forces inside atoms are much stronger than the forces that hold molecules together.
2.2.7. All chemicals from the atmosphere are non-metallic or non-metallic compounds.
2.3. Chemicals of the hydrosphere
2.3.1. One of the special properties of water is that it ia a liquid at room temperature
2.3.2. Another strange property of water is that as it cools to below 4ºC it contracts and expands, it then forms a solid which we know as ice
2.3.3. Saltwater, the type that we find in the sea is a conductor and conducts electricity. But pure water is not a conductor.
2.3.4. Most solvents do not dissolve ionic compounds but water does, this is another of its special properties.
2.3.5. Ice is less dense than water so it floats
2.3.6. The structure of water can help us explain some of its amazing properties.
2.3.6.1. The attractions between water mol and their angular shape mean that they line up in icr to create a very open structure.
2.3.6.1.1. As a result ice is less dense than water.
2.3.6.2. Small charges on opposite sides of the molecules cause slightly stronger attractive forces between the molecuels
2.3.6.3. The small charge also hels water dissolve ionic compounds by attracting the ions out of their crystals
2.3.6.4. The electrons are not evenly shared in the covalent bonds between atoms.
2.3.6.5. The oxygen atom has more than its fair share. It also has four unshared electrons in its outer shell.
2.3.7. Another strange property of water is that as it cools to below 4ºC it contracts and expands, it then forms a solid which we know as ics
3. Chemistry 6
3.1. The Chemical industry
3.1.1. The chemical industry converts rawe materials such as crude oils or natural gases into useful products.
3.1.2. The industry makes bulk chemicals on a scale of thousands or even millions of tonnes per year
3.1.3. On a much smaller scale the industry make fine chemicals such as drugs herbacides and pestacides.
3.1.4. There are a lot of different people in the industry not only chemists. People are needed to watch the levels of temperature in the experiments and be there incase anything goes wrong.
3.2. Acid and alkalis
3.2.1. Not all acids are dangerous.
3.2.2. Even the ones that sound dangerous anent when they have been diluted.
3.2.3. There are several different types of acids, for example organic acids
3.2.4. Hydrogen chloride is a gas and becomes hydrochloric acid when it dissolves in water.
3.2.5. Alkalis can be used in things such as antacid tablets, like the ones that are sold in pharmacies
3.2.6. Antacid tablets can be taken to combat things such as heartburn.
3.2.7. Antacids are usually insoluble in water. Other chemicals in medicines are usually solulable
3.2.8. There are also mineral acids; for example Sulfuric acid, hydrochloric acid, and nitiric acid. The pure acids are all molecular.
3.2.9. Antacids are soluble in water and give a solution with a pH above 7.
3.2.10. Some of the names of acids get changed slightly so that they can be said easier in everyday life.
3.2.10.1. An example of this is sodium hydroxide being changed to caustic soda
3.2.11. How acidic or alkali something is is measured on a scale called the pH scale.
3.2.11.1. There are other scales the the most commonly used one is the pH scale
3.2.11.2. There are certain tools that can be used to measure pH, these include Universal Indicator (a liquid that can be added to a solution in order to change the colour), digital pH measurers and many others.
3.2.11.3. The pH scale goes from 1 (or zero) to 14, with water (7) being neutral
3.2.11.4. The higher the number the more alkali the substance is.
3.2.11.5. The lower the number the more acidic the substance is.
3.2.11.6. A number for the pH can appear in such places as medicine, shampoo or other household proucts.
3.2.12. Some plants can change colour depending on what acidity the soil is.
3.2.12.1. An example of this is Hydragenas. They arre blue if grown in acidic soil and pink if grown in alkaline soil.
3.2.13. Acids can react with metals to produce salts.
3.3. Salts from acids
3.3.1. Acid + Metal -> salt + hydrogen
3.3.2. Not all metals react this way, metals below lead in the order of reactivity fo not react with acids.
3.3.3. Even with lead it is hard to detect any change in a short period of time.
3.3.4. Acid + metal oxide -> salt + water
3.3.5. Acids react with a metal oxide or hydroxide to form a salt and water. No gas is formed.
3.3.6. The reaction between an acid and a metl oxide is often a vital step in making useful chemicals from ores.
3.3.7. acid + metal carbonate -> salt + water + carbon dioxide
3.3.8. Acids react with carbonates to form a salt water and bubles of carbon dioxide gas.
3.3.9. Chemists have theory to explain why all the different compounds that are acids behave in a similar way when they react with indicators, metalsm carbonates, metal oxides, and metal hydroxides.
3.3.10. We think that acids do not simply mix with the water when they disolve. They react
3.3.10.1. When they react they produce hydrogen ions (H+).
3.3.11. Alkalis such as soluble metal hydroxides are ionic compounds.
3.3.11.1. They consist of metal ions and hydrogen ions (OH-)
3.3.11.2. When they disolve they add hydrogen ions to the water.
3.3.11.3. It is these ions that make the solution alkaline
3.3.12. Alkalis are neutralised when the hyrdrogen ions (OH-) react with the hydrogen ions in the acid. This then forms H2O. commonly known as water.
3.3.12.1. The remaining ions in the solution make a salt.
3.4. Purity of chemicals
3.4.1. Chemicals do not aleways have to be pure in order to be able to use them.
3.4.2. Some are used unpure as they are chaper and ocasionally more efficient
3.4.3. Purifiyinmg a chemical is done in stages. Each stage takes time and moeny.
3.4.4. We only purifiy a chemical if it is worth the money in the long run.
3.4.5. Somethimes it may cost more to purify the chemical than it does to buy the chemical. This would render that way of purifying the chemical uneconomical
3.5. Energy changes in chemical reactions
3.5.1. Most chemical reactions need a supply of energy to get them started.
3.5.2. Some also need energy to keep them going.
3.5.3. Reactions can give out energy to their surroundings, meaning that the surroundings get hotter, this is called an exothermic reaction.
3.5.4. They can also gain energy from their surroundings, meaning that their surroundings get colder. This is called an endothermic reaction
3.5.5. It is possible to tell weater a chemical reaction is endothermic or exothermic by recording the temperatures of the reactants before and after the reaction has taken place.
3.5.6. People workin in the chemical industry need to know what type of reaction is being performed so that they can see what will be needed for the reaction to take place.for example id it is endothermic they will need fuel to provide heat and vice versa.
3.5.7. Energy given out by exothermic reactions can be used in different ways, for example polwering a part of the plant.
3.6. Rates of reactions
3.6.1. The rate of a reaction can be changed by using a catalyst.
3.6.2. A catalyst is a substance which speeds up a reaction, but is chemically unchanged at the end of the reaction. When the reaction has finished, you would have exactly the same mass of catalyst as you had at the beginning.
3.6.3. Catalysts are elements or chemicals that speed up reaction rates by producing or creating more of whatever causes the reaction to happen in the first place.
3.6.4. The rate of a reaction is a mesurement of how fast the reaction isgoing.