ChemistryThe early atmosphere started off as pretty much nothing, everything was molten and so any atmosphere melted away.Slowly however, the Earth began to cool down and a thin crust formed. Volcanoes formed and erupted, letting off steam ( water vapour) and carbon dioxide. When the water vapour condensed, the oceans formed. Marine life began to develop, taking in the carbon dioxide from the ocean. When they died, the carbon dioxide got trapped within carbonate rocks. Green plants evolved and took in the carbon dioxide, releasing oxygen during photosynthesis. The oxygen levels gradually increased. The increase in oxygen levels meant that some lesser-developed organisms died, letting other ( more developed) organisms to evolve. The oxygen levels also created the ozone layer- this blocked out the suns harmful rays, enabling even more developed organisms to evolve- eventually leading to us! Today's atmosphere contains:0.04% Carbon dioxide78% Nitrogen21% Oxygen1% Argon and other gasses
Today's Atmosphere is still changing, this is because of Human activities such as : burning fossil fuels, this releases huge amounts of carbon dioxide into the atmosphere, deforestation - Plants take in carbon dioxide during photosynthesis and release oxygen. By cutting them down and burning them there are less plants to take in the Carbon dioxide, also the carbon dioxide taken in is released when they're burnt. livestock farming releases large amounts of methane into the atmosphere because animals release this when they pass wind ( for example cattle does this). Volcanic activity also changes the atmosphere, for example when a volcano erupts sulphur dioxide is released high into the air. It reacts with sunlight, water and oxygen to form volcanic smog. Carbon dioxide is also released into the air.We can learn about the past atmosphere by using antarctic ice cores- these are useful because every year a layer of ice forms and bubbles of air get trapped inside it. Examining these in ultra precise measurements we can learn more about the atmosphere. No one can know for sure what the atmosphere was like before but it gives us a better idea.A way of investigating the proportion of oxygen in the atmosphere is by heating an excess of copper in a tube and pass air over it using two syringes. You can see here how much oxygen can be used up. This happens because the copper reacts with the oxygen in the air to make copper (II) oxide . 2Cu + oxygen = 2CuO
Rock types. Sedimentary - Sedimentary rocks are formed by this process:1) layers of sediment lay down under the water of a lake or sea, 2) Over years, layers and layers of these sediments push down on the underneath layers. This means that, because of the weight, all the water is squeezed out.3) fluids flowing through the pores create natural mineral cement which sticks the sediments together.Sedimentary rocks can contain fossils- because it wasn't formed at high temperatures, the remains of dead organisms remain. They are often soft and can be easily eroded by wind, rain or waves.examples of these are limestone and chalk.Igneous - Igneous rocks are formed from cooled magma, there are two ways Igneous rocks can be formed: Extrusive and Intrusive.Extrusive rocks are formed outside the crust, when the lava quickly cools- forming small crystals. Intrusive rocks are cooled slowly (because it's so hot) underground - it forms large crystals.Metamorphic - metamorphic rocks are formed by immense heat and pressure over time. They were once sedimentary or igneous rocks but as they undergo this change the texture and mineral structure changes - the chemical composition is often the same as the sedimentary or Igneous rock.If a metamorphic rock melts it becomes magma and is lost, unless it forms Igneous rocks. They're often hard, have an even texture and very high temperatures create small crystals.
Limestone is a types of sedimentary rock that is used for many things, for example:building materials - Limestone blocks are used to build cathedrals, statues and old buildings. It can be used to make cement, glass, road surfacing and concrete and therefore it's quarried on a large scale.-Cement is made by powdered clay being added to powdered limestone and heated in a kiln. This can be used within the building of houses etc. -Glass is made by sand, sodium carbonate and limestone being added together and melted. -Concrete is made by using the cement mixture, and adding sand, water and gravel.-Limestone is crushed up and made into chippings which can be used in road surfacing. Limestone provides things that people want, for example it's used in dyes, paints and medicines. It is used to neutralise acidic soil and acidity in lakes caused by acid rain.Limestone is also used in power station chimneys to neutralise sulphur dioxide (the cause of acid rain).Limestone is virtually insoluble in water but acid rain is a large problem.Because we have to quarry Limestone from the ground, it has many benefits and also disadvantages.Benefits & Disadvantages+provides jobs and brings money into local economy. +this can lead to local improvements in transport, roads etc. +when the quarrying is over, landscaping is often required by the planning permissions.-huge ugly holes are made-processes and lorries cause dust and noise and pollution. - quarrying destroys the habitats of animals and birds.Thermal decomposition of limestoneLimestone is mainly calcium carbonate. when heated, this thermally decomposes to make calcium oxide and carbon dioxide.- this happens to other carbonates as well. + for example, zinc carbonate and copper carbonate thermally decompose in the same way as calcium carbonates to form an oxide and carbon dioxide. + If the carbonate is placed in a boiling tube, we can see that the product formed is carbon dioxide by bubbling it through limewater. Limewater turns cloudy when carbon dioxide is bubbled through. - some carbonates undergo thermal decomposition more easily than others, depending on the stability of the metal carbonate. Less stable carbonates decompose faster. - sometimes there is a colour change of the substance, for example copper oxide turns black. When you add calcium oxide to water you get calcium hydroxide. Calcium hydroxide is an alkali can be used to neutralise acidic soil in fields. Calcium hydroxide dissolves in water to produce limewater.
ATOMS AND MASS IN CHEMICAL REACTIONS!Atoms are never lost or made in chemical reactions, they are simply transferred - so the elements still have the same atoms at the end they've just moved around to give different products with different properties from the reactants. This is why symbol equations must be balanced! So if , for example, there were two oxygen atoms on the reactant side of the equation- there would have to be two oxygen atoms on the product side.Therefore, the mass doesn't change either ( if you do the reaction in a sealed container).A good example of this is to do a precipitate reaction - this happens when two solutions react to form an insoluble product within the solution. The solid is said to precipitate out- this is the precipitate. For example- copper sulfate + sodium hydroxide creates copper hydroxide and sodium sulfate. Copper hydroxide is an insoluble product and so precipitates out. The mass will stay the same from the start of the experiment to the end.+ the easiest way to balance equations is to do them one type of atom at a time. Sometimes this creates other imbalances but keep going until everything works. State symbols - (s) - solid (l) - liquid, (g) - gas, (aq)- aqueous - dissolved in water.C1b topic 3- hazard symbols. ( look at the mindmap for the symbols)oxidation - gives out oxygen allowing other materials to set alight and burn more fiercely- liquid oxygentoxic- can cause death if swallowed absorbed through skin or if it's somehow allowed into the bloodstream- hydrogen cyianideirritant - can cause red blistering or swellingflammable - materials that set alight very easilycorrosive - damages or destroys body tissues- very concentrated sulphuric acidharmful- not quite as dangerous as toxic substances but they can cause damage to tissues etc.substances can be acids alkali or basesacids are those below 7 on the pH scalebases are above 7and alkalis are bases that can dissolve in water.We get the colours of the pH scale by adding universal indicator to the substance. Acids tend to be a red(ish) colour, the deeper the red, the more acidic the substance is. Green is neutral ( pure water is an example). Purple is alkali.The stomach produces hydrochloric acid.
Biology - B1.1- classificationKeywords :Heterotrophic - eats other thingsautotropic - makes its own foods by photosythesis for example.saprophyc- digests other organisms outside its cell bodyunicellular - made of one cell, ( for example, bacterial cells)multicellular- made of lots of cells ( for example, humans)Classification - the five kingdoms are separated into ( in order) :species ( groups of organisms that have things in common)genus (several species with characteristics in common)family ( composing of several different genera- genus)order (composing of several different families)class ( etc.)phylumHomosapien for example shows this, "Homo" is the species, "sapien" is the genus. The reason for the latin name when giving a species of animal its correct name means that people from all over the world can understand it which allows for study and identification everywhere. species that are at threat can be preserved more efficiently this way.Five kingdomsAnimalia - animals are multicellular, they do not have cell walls ( they have cell membranes ) and they don't have chlorophyl. They therefore do not create their own food and so are heterotrophic, eating of other organisms.plantae - all plants. they are multicellular, they have chlorophyl and have cell walls. They therefore feed autotrophically, producing their own food via photosynthesis.Fungi- multicellular, they have cell walls but no chlorophyl. They feed saprophyically ( feeding off dead organisms and decaying material).Protocisita - protocists are unicellular, they have a nucleus. For example, algae.Prokaryotes - unicellular, have no nucleus. For example, bacteria.Viruses are not counted into any of the five kingdoms as they cannot reproduce themselves, they only attack other cells, meaning that when the cell multiplies itself it multiplies the virus with it. They are smaller than bacteria, they have a protein coat containing only a few genes. They are non-living.Vertabrates- have a rod supporting the running length of the body.e.g. Humans( Homosapiens) have a spine to support the running length of our body. Supported into five different classes- amphibians, fish, mammals, reptiles and birds.These are placed into groups depending on oxygen absorption - through lungs, gills, skin reproduction- how do they reproduce? externally or internally? oviparious ( lays eggs) or viviparious (gives birth to live young- like us). Thermoregulation- how do we control our internal temperature? homeotherms ('warm blooded' - kept at a constant temperature) or poikilotherms ('cold blooded' - changes with external temperature). Therefore, in order to classify which groups to put the animal in you would look at keys like this, shown underneath, although many are difficult to classify as they may have more than one characteristic from each. If this happens it will be placed in the one that it is more like. Variation in species may complicate an accurate classification, for example a bird of the same species may have a different coloured stripe on one side. It's still the same species, just with a stripe. Another thing that may complicate it is that hybrids in ducks may create a whole different species of duck, but also they might not be ( weird huh?) also, a group of the same species may be separated by an environmental factor such as mountains. On each side of these mountains the environment may be different and so the species will adapt differently, creating new characteristics and possibly, eventually creating a different species all together.
Hybridshybrids are animals which are the offspiring of two similar species. For example, a horse and a zebra may be bred together to form a hybrid. Some may be fertile, whilst others may not. another example is if a grizzly bear mated with a polar bear its offspring would be a grolar bear. These hybrids may be classed as a different species because they have been found to have more characteristics from that species.Asexual reproductionAsexual reproduction needs only one parent ( the reason for the "a") in comparison to sexual reproduction which needs two parents. There is, therefore, no fusion of gametes or mixing of genetic information- creating an offspring which has the same DNA structure, the same genes, the same chromosomes, as the parent. Hereby creating a genetically identical offspring- they're clones!This asexual reproduction, is most common in plants rather than animal ( but in some species, this may occur). Potatoes and daffodils do this. A daffodil for example, creates a lateral bulb in the first bulb; underneath the flowering bud- when the season of that bulb falls away, the lateral bulb begins to grow ready for next seasons flowering. This is shown in the picture , top right of the screen.Adaptions and characteristicsExample: polar bearsenvironment : live in ice cold, polar regions, temperatures are cold and food is often sparse.adaptations: blubber underneath and around the polar bears body provides insulating warmth and energy. Its white appearance gives it camouflage against predators, Its small surface area: volume ratio means that heat loss is kept to a minimal and its greasy coat allows it to be streamlined in water and to shed the water when it's on the ice. the fur around its body also provides warmth. Its long claws/ teeth are perfect for catching prey.Example : The Pompeii wormenvironment : hydrothermal vents, temperatures are hot, there's a high pressure and the life here, including bacteria is not often there- they're killed off by the heatadaptations: A thick layer of bacteria protects the worm from the heat, and predators are unable to get to it because of the papery tube wrapped around it. organisms like this may use chemical energy from the minerals around the vent to produce their energy for life.This is an example of an extremophile - it is tolerant to high temperature and high levels of pressure. Example: DEEP sea fishenvironment: dark, lots of predators, sparse food.adaptations: some fish, like the hatchet fish, have large glowing eyes which allow them to see, others like firefly squids use their light to attract prey by flashing it on and off. Some have large eyes, adapted to be very sensitive and see everything around them, others are almost blind and so detect the vibration in the sea to listen for prey and predators. Others have large mouths and stomachs to engulf as much food as possible when they can find any. Fish eat every couple of days.