Chemistry core AQA GCSE 1A : ATOMS, METALS, ATOMS, METALS, ROCKS and FUELS ~REVISION GUIDE~ By Elizabeth Garwood Go!
CONTENTS 1. a 1. atoms and elements 2. compounds and mixtures 3. limestone 4. the limestone cycle 5. metals 6. the reactivity series 7. more metals 8. aluminium and titanium GO! Actually, I'm done revising...
ATOMS AND ELEMENTS home This diagram shows a helium atom. In the middle is the NUCLEUS, which is made up of PROTONS (positive charge) and NEUTRONS (no charge). Orbiting this are ELECTRONS (negative charge) Almost the whole of the atoms mass is in the nucleus, but most of the atoms size is the paths of the electrons, which are called shells. Atoms can have different numbers of protons, neutrons and electrons in them, but it's the number of protons that decides what kind of atom it is. If a substance contains only one type of atom, it is called an element.
COMPOUNDS AND MIXTURES When different elements react, atoms form chemical bonds with other atoms to Form COMPOUNDS. Making these bonds involves the atoms taking away, giving or sharing electrons, but the nuclei remain the same. The properties of a compound are totally different from the properties of the original elements The formula of a compound will show you what is in it, eg carbon dioxide CO 2 The capitol C is the chemical symbol for carbon The capitol O is the symbol for oxygen The small 2 shows that for every atom of carbon, there are 2 of oxygen (you will often get a question about balancing equations. You just have to remember that atoms aren't made or lost in a chemical reaction, so both sides of the equation must have the same number of atoms.) home A chemical bond!! (well I think its funny )
LIMESTONE Limestone is a whitish grey coloured rock that is made from sea shells. It is very useful and can be made into many different things, including statues, building blocks, and road surfacing Quarrying it out of the ground can cause lots of problems, including: - environmental and visual pollution- the quarrying leaves lots of great big holes all over the place. - cement factories make lots of dust (bad for people with breathing problems like asthma) - energy used in the processes is likely to come from fossil fuels, which produce greenhouse gases etc. - limestone and limestone products all need to be transported to the factories and to where they will be sold (lorries exhaust fumes, etc.) home Limestone products include: - glass (heated with sand and sodium carbonate until it melts) - chemicals used in dyes, paints and medicines also come from limestone. - Limestone products can neutralise acidic soil, and acidity in lakes and rivers that is caused by acid rain. - also used in power stations to neutralise sulphur dioxide, which causes acid rain. The quarry provides lots of jobs, which is good for the economy. So really, limestone is jolly useful =D Limestone is made out of lots of sea creatures that have been squished and turned into rock.
THE LIMESTONE CYCLE Calcium carbonate LIMESTONE CaCO 3 Calcium oxide+CO 2 Quicklime CAO Slaked lime Calcium hydroxide CA(OH) 2 Lime water CA(OH) 2 + heat CO 2 + H 2 O + more H 2 O SIMPLES!! So, if you heat limestone, you get quicklime and carbon dioxide. If you add a bit of water, you get slaked lime. If you add more water to this, you get lime water, and bubbling CO 2 through lime water produces limestone. home
METALS Most of the elements are metals. They are all slightly different, but they have the same basic properties. (and lots of them are shiny =D) Metals are strong and hard to break, but can be bent or hammered into different shapes so useful structural materials. They are good conductors of heat and electricity Metals (especially transition metals) have lots of everyday uses. Metal problems: -some corrode when exposed to air and must be coated or painted, or they will lose their strength -metal fatigue- if a metal is under too much stress, it becomes weak and may break. home The structure of metals gives them their properties. > metals have a special type of bond that allow the outer electrons from each atom to move freely through the metal. > these 'free electrons' can carry energy very quickly, which is why metals conduct heat and electricity so well. metal atoms are often found joined to other atoms as compounds, which can be very hard to separate. -Rocks are made of minerals (elements and compounds) -An ore is a mineral that contains enough of a metal that makes it worthwhile to extract the metal from it. -There is only a limited amount of ores- they are a finite resource. No, an ORE, not an oar!!
THE REACTIVITY SERIES home This is the order of the reactivity of metals, the most reactive at the top and the least reactive at the bottom. There's also a Pokémon mnemonic to help you remember them =] Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Copper Silver Gold Platinum Pikachu Slapped Charmander Manically, And Clefairy Zapped Igglybuff To Legally Capture Skitty's Gothic Psyduck.
MORE METALS Mining ores is a bit like mining limestone; there are pros and cons. Pros: Useful products can be made from the ores Provides local people with jobs Brings money into the area, so services and stuff can be improved. Cons: Bad for the environment Causes noise, scarring of landscape and loss of habitats Deep mine shafts are dangerous. - ANY METAL BELOW CARBON IN THE REACTIVITY SREIES CAN BE EXTRACTED USING CARBON, BUT THOSE ABOVE IT MUST BE EXTRACTED BY ELECTROLYSIS. - COPPER IS PURIFIED BY ELECTROLYSIS TO MAKE IT A BETTER CONDUCTOR Metals can also be made more useful by mixing small amounts of other metals to make an alloy. Different elements have different sized atoms, so the new atoms will upset the regular pattern of atoms in the element, making it much stronger. You can also get some 'smart alloys' that can return to their original shape when they are heated. home
Aluminium and titanium Aluminium is lightweight and corrosion resistant (it is a reactive metal, but the outer layer reacts very quickly with air to make aluminium oxide, which sticks to the aluminium underneath and stops it reacting any more) and it makes very strong alloys. It is used a lot for things like aeroplanes, window frames and electricity cables. However, you can't extract it by reduction with carbon (the cheap way) it must be extracted by electrolysis which is expensive. Titanium is also low density. Unlike aluminium it is very strong. It has a low chemical reactivity which makes it resistant to corrosion. Titanium is often used in spacecraft, jet engines and hip replacements. Like aluminium, the extraction of titanium is expensive. It is a very long winded process with lots of little stages. NYEOOOW!! home