CCEA CHEMISTRY-CHEMICAL PATTERNS AND OUR ENVIRONMENT

Acids and Bases can be Bases-baking soda,Ammonia-in cleaning found in the home Products Acids-vinegar,citric acid-lemon AntAcids- Milk of Magnesia Juice Sodium Hydroxide-oven and drain cleaners PH less than 7 PH above 7

Universal indicator is used to tell if a substance is acid or alkali From pH1 acid to pH 14 alkali

Hazard symbols Indicators It is possible to tell if a solution is acidic or alkaline by using an indicator. An indicator is a substance which has different colours when it is in acidic or alkaline conditions. Litmus is probably the most well-known indicator. This is red in acids and blue in alkalis. Litmus can be used as a liquid, or as litmus paper.

Plant dyes can be used from plants to be indicators Such as beetroot, redcurrants and red cabbage Key Vocabulary Temperature – how hot or cold something is. Measured in degrees Celsius (oC). Particle – a tiny amount of something. You can’t see them with your eyes! Melting – the process of a solid heating and changing into a liquid. Evaporation – the process of a liquid heating and changing into a gas. Condensation – the process of a gas cooling and changing into a liquid. SOLID Freezing – the process of a liquid cooling and changing into a solid. Precipitation – When water or snow fall from a cloud

LIQUID

GAS

Neutralisation

Acids react with alkalis to form salts. These are called neutralisation reactions. In each reaction, water is also formed: acid + alkali → salt + water Example hydrochloric acid + sodium hydroxide → sodium chloride + water

HCl + NaOH → NaCl + H O 2 This can be monitored When an acid and alkali is neutralised by computers an pH what is left is pH7 sensors NEUTRAL NOT ACID OR ALKALI

Neutralisation is used in everyday life- indigestion(sore tummy) can be cured by taking baking soda or tablets that contain weak bases that are OXIDES, Farmers also treat acid soils HYDROXIDES or CARBONATES with LIME-an alkali to make it neutral and better to grow crops Indigestion is caused by excess ACID in the stomach How “Rennies” or indigestion tablets work

The word equation for the reaction between Sodium carbonate and hydrochloric acid is: Word Equation Sodium carbonate + Hydrochloric acid --> sodium chloride + carbon dioxide + water

Symbolic EquationThe balanced equation is:

Na2CO3(aq) + 2HCl(aq) --> 2NaCl(aq) + CO2(g) +H2O(l) Th Carbon Dioxide gas is given off how can you test this

Baking powder is a mixture of Sodium Hydrogen Carbonate and tartaric acid- used in When heated baking and cooking causes Hydrogen carbonates also break down to release carbon dioxide when heated, but different products are formed. CO2 to be made allowing Here are the equations for the thermal decomposition of sodium hydrogen carbonate: mixtures to rise sodium hydrogen carbonate → sodium carbonate + carbon dioxide + water

Sherbet causes a fizz on 2NaHCO3 → Na2CO3 + CO2 + H2O the tongue because the Sodium hydrogen carbonate is used in baking powder. It reacts with acids in the powder to release carbon dioxide gas. This makes batter or sponge mixtures rise when they are cooked. citric acid and NaHCO3 will react together to make (sodium bicarbonate) + (citric acid) --> (sodium citrate) + CO2 gas when it is moistened by the saliva in (carbon dioxide) + the mouth (water) History of the periodic table Mendeleev's periodic An English scientist called John Newlands table-“The DUDE” put forward his law of octaves in 1864. He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found that each element was similar to the element eight places further on. Newlands' table showed a repeating or periodic pattern of properties but In 1869 a Russian chemist called Dmitri he put iron in the same Mendeleev published a periodic table. group as oxygen and Mendeleev also arranged the elements sulphur, which are two known at the time in order of relative non-metals. As a result, his atomic mass (which was wrong) , table was not accepted by but he did some other things that made his other scientists. table much more successful. He realised Mendeleev’s method of arranging elements meant properties of elements were related to their there were gaps in his horizontal rows or 'periods'. atomic mass in a 'periodic' way, and But instead of seeing this as a problem, arranged them so that groups of elements Mendeleev thought it simply meant that the with similar properties fell into vertical elements which belonged in the gaps had not yet columns in his table. been discovered.

He was also able to work out the atomic mass of the missing elements, and so predict their properties. And when they were discovered, Mendeleev turned out to be right. All substances are made from atoms. The atoms of any element are different from the atoms of any other element. So iron contains a different sort of atoms from those of sulphur, and the atoms in carbon are different from those of oxygen. Every element has its own chemical symbol. For example, iron is Fe, sulphur is S, sodium is Na . The vertical columns in the periodic table are called groups. Each group contains elements that have similar properties because they have the same number of electrons in their outside shell/orbit. The periodic table has eight main groups. For example, group 1 contains very reactive metals such as sodium - Na - while group 7 contains very reactive non-metals such as chlorine – Cl. Group 0 is called the NOBLE Gases they have full outer energy levels and do not react with anything because of this arrangement of electrons

Noble The number of Protons gases an atom has is called Halogens the Atomic Number Alkali Metals

The nucleus of the atom contains Protons which have a charge of +1 and Neutrons which have no charge Electrons have a charge of -1 and orbit the nucleus in shells or orbits. The orbits fill from inside to out with 2,8,8 electrons New substances are formed by chemical reactions. When elements When elements are joined to cause a chemical react together to form compounds their atoms join to other atoms reaction, no atoms are made or lost during the using chemical bonds. process - but at the end of it they are joined Chemical bonds involve electrons from the reacting atoms. Bonds can differently from the way they were at the start. This form when: means that the • electrons are transferred from one atom to another, so that one mass of the substances at the start - the reactants – atom gives electrons and the other takes electrons, or is the same as the mass of the substances at the end • Electrons are shared between two atoms. - the products.

Here is the balanced symbol equation: 2Cu + O → 2CuO 2 2+ 2- 2H2 + O2 → 2H2O

Reactions between Metals and Non Metals Compounds made from Non Metals are usually involves the giving or taking of electrons made of molecules that share electrons to make all the atoms have stable full outer to obtain a stable full outer shell of shells. This type of bonding is called IONIC electrons this type of bonding is called as it makes charges atoms called Ions. COVALENT Group 1 Alkali Metals Reactions in Water Sodium- Na Sodium also floats but it moves on the surface These are grey coloured and soft, solids that of the water much more quickly. It can be quite easily cut by a scalpel. hisses/fizzes loudly the gas made can They are all very reactive. They are stored sometimes burn with a yellow flame, it can under oil to stop them reacting with the air. explode with a pop. They must not touch human skin. All Alkali Metals react with water. Potassium-K As we move down group 1 the metals become Potassium floats on the water but it moves more reactive. rapidly across the surface and reacts Lithium – Li when lithium is put into water it vigorously, the gas made burns with a floated on the water and moved slowly Lilac/purple flame and it eventually disappears hissing/fizzing giving off heat and a gas. with and explosive crack. Potassium is more reactive than Sodium. As the elements go down group 1 they Word equations become more and more reactive For reaction of Group1 Metals with water.

Lithium + Water → Lithium Hydroxide + Hydrogen gas

Sodium + Water →Sodium hydroxide + Hydrogen gas

Potassium + Water → Potassium Hydroxide + H2

All group 1 metals react with water to give a metal hydroxide and hydrogen gas given off( Fizzing ) All the other metals in the periodic table are less reactive than the group 1 metals. The reactivity of metals have been organised into an order by carrying out several different experiments. Metals on the reactivity series also can Reactions with water react with each other. Reactions with steam These reactions are called Reactions with dilute acid displacement reactions. Reactions with Conc acid. When a compound containing a metal Most Reactive – is dissolved in water and another metal K- Potassium Please is added a displacement reaction can Na-Sodium Send occur. Ca- Calcium Charlies This displacement reaction will Mg- Magnesium Monkeys Al- Aluminium And ONLY happen if the metal added is Zn- Zinc Zebras MORE reactive than the one in solution Fe- Iron In Displacement reactions can be used to determine a Pb- Lead Lead reactivity series- Cu- Copper Cages A set of reactions are carried out between metals and Ag- Silver Securely their metal salts in solution. Au- Gold Guarded The metals are usually placed into solutions of the metal salt ( usually sulphate) the results are then recorded in a Iron nail is placed into Copper Sulphate solution. table this is used to determine which substance is the most reactive etc. Fe + Cu SO4→ Cu + Fe SO4 Oxidation and Reduction Solid Solution Solid Solution Oxidation is the gain or addition of Oxygen in any reaction. Blue Clear Reduction is the loss or removal of Oxygen in any reaction. In most reactions oxidation and reduction both take place at the same time and are Iron displaces the copper so must be more reactive!! often referred to as REDOX reactions Hydrocarbons Most of the compounds in crude oil are hydrocarbons.COAL OIL GAS Alkanes are saturated hydrocarbons. This means that their This means that they only contain hydrogen and carbon atoms are joined to each other by single bonds. This carbon atoms, joined together by chemical bonds. are FOSSIL makes them relatively unreactive, apart from their reaction with There are different types of hydrocarbon, but most of FUELS made of oxygen in the air, which we call burning or combustion. the ones in crude oil are alkanes. HYDROCARBON Fractional distillation of crude oil Alkanes The different parts of the crude oil have different boiling points, The alkanes are a family of he substances in crude oil can be separated using fractional hydrocarbons that share the distillation. The crude oil is evaporated and its vapours allowed to condense at different temperatures in the fractionating same general This is the sequence of events in column. Each fraction contains hydrocarbon molecules with a formula. This is: distillation: similar number of carbon atoms. CnH2n+2 heating evaporating cooling condensing Hydrocarbons with small molecules make Fuels burn when they react with oxygen in the air and GIVE better fuels than hydrocarbons with large OUT ENERGY molecules because they are volatile, flow THE FUEL IS OXIDISED – OXYGEN is added to the fuel. easily and are easily ignited. hydrocarbon + oxygen→ water + carbon dioxide

Sulphur Sulphur can be removed from fuels at the oil refinery. Most hydrocarbon fuels naturally contain some This makes the fuel more expensive to produce, but it sulphur compounds. prevents sulphur dioxide being produced. When the fuel burns, the sulphur it contains is oxidised to sulphur dioxide. Global warming The combustion of a fuel may release several Carbon dioxide from burning fuels causes global gases into the atmosphere, including: warming, a process capable of changing the • water vapour world’s climate significantly. • carbon dioxide causes Global Warming • carbon monoxide Global dimming • particles causes Global Dimming makes the sun Tiny particles that are released when fuels appear dimmer are burned cause global Dimming. • sulphur dioxide causes acid rain The amount of sunlight reaching the Earth’s Nitrogen Oxides cause acid rain surface has decreased by about 2 per cent every ten years, because more sunlight is being reflected back into space. The particles from burning fuels reflect sunlight.

Biofuels are new fuels which are becoming widely used to provide energy as other sources of fuels become more expensive an not as easily available

Biofuels come from the products of living organisms, such as methane biogas from decaying manure and sewage. Vegetable oils are also used as fuels for vehicles. Some of this biodiesel is made from waste cooking oil and rapeseed oil. Plastic/Polymers

When lot of the small molecules called MONOMERS join together this is called PLOYMERISATION

The MONOMER must have a C=C double bond to be able to polymerise

In polymerisation a double bond becomes a single bong and joins to the next molecule Polymers are used to make bags bottles containers and toys for example. 2Types of polymer The Thermoplastic – reheated and reshaped- If these 2 polymer of can be recycled types are polythene mixed it can Thermoset –after moulding they cannot is written make as this be reshaped only burn when heated recycling Small n means a very difficult 13 large number joined together Materials obtained or made from living Properties and Uses things are sometimes called natural The use of a material is dictated by its properties i.e. windows are made materials, whereas synthetic materials from glass because it is transparent. are made from chemicals. Today, 4 main property groups synthetic materials offer us more Physical properties durability at a lower cost than the Chemical properties natural materials we used to use. These Availability are some of the reasons why linen is no Cost longer made in NI The best fitting material that matches the needs of the object is chosen.

Synthetic and natural materials

The materials we use are chemicals or mixtures of chemicals. For example, sugar is a chemical, but chocolate is a A composite material is mixture of chemicals, one of which is one that combines the sugar. properties of 2 or more materials for a Materials can be obtained or made from particular purpose living things. Examples include cotton, paper, silk and wool. These are called Concrete is often reinforced with steel. A steel natural materials. support is made by joining steel bars or cables together and this is then usually surrounded by Materials can also be made from a mould. Concrete is poured into the mould, chemicals. Examples of these include where it fills the gaps in the steel support and plastics such as polythene. These are sets hard. Reinforced concrete is an example of called synthetic/Man Made materials. a composite material. Aluminium electrolysis – HIGHER ONLY

Aluminium is the most abundant (found in large quantities) metal on Earth. But it is expensive because of the amount of electricity used in the extraction process. Aluminium ore is called bauxite. The bauxite is purified to yield a white powder - aluminium oxide Al2O3

First the aluminium oxide must be melted so that electricity can pass through it. Aluminium oxide has a very Ions are high melting point (over 2000°C) it is dissolved in molten able to cryolite - an aluminium compound with a lower melting point move. than aluminium oxide. The use of cryolite reduces the Positive energy costs. The diagram shows an aluminium ions electrolysis. Both the negative electrode called (cathode) and positive electrode (anode) are CATIONS made of graphite, carbon. move to the Aluminium metal forms at the negative electrode electrode it sinks to the bottom of the tank called the and is tapped off. CATHODE. Negaitive Oxygen forms at the positive electrodes. This ions oxygen reacts with the carbon electrodes, called forming carbon dioxide they gradually burn ANIONS away. The positive electrodes have to be move to replaced frequently. This costs money. the ANODE Finger prints How to lift a print •Sprinkle Prints are individual aluminium/carbon and forensic scientists powder on surface have to dust powder • on them to make Use paintbrush to rub them seen off excess powder EACH print is • unique Place a piece of tape on print and remove. •Put tape on to a piece of card. Surface Powder used • White Carbon Black Or Photograph print at science Black/Shiny/mirrored Aluminium Powder • 4 types of print Check print with Arch Chemical way of showing known database to Whorl prints compare known prints Loop UV light to show them Composite (made of two loops) Use Iodine fumes or Everyone has a different superglue fumes to make fingerprint pattern the print clear Prevention of forgery of Bank notes Clothing Fibres Bar codes serial numbers If a crime is committed some clothing Special paper fibres will be left behind. These can be collected and examined Watermarks using an SCANNING ELECTRON Holograms MICROSCOPE. The fibres can the be compared with UV light is used to test for counterfeit bank notes the clothing of the suspect. The fibre will have different colours, Use of special pen/marker to check the paper twist pattern and weave pattern, there may also be stains on the fibres blood saliva sweat. Hair is also a fibre and this can be Genetic Fingerprinting compared in the same way to identify DNA can be extracted from those present at a crime scene. hair, blood, skin etc. found at a crime scene. This DNA is compared with others known as DNA Fingerprinting. This makes a series of bands if all the band match the DNA is from the same person and they were at the crime scene Flame tests Some common metals and their flame test colours

Metals change the colour of a flame when they are metal flame test colour heated in it. Different metals give different barium pale green colours to the flame, so flame tests can be used to calcium yellow-red identify the presence of a particular metal in a copper green-blue sample. This is how you would carry out a typical lithium red flame test: 1.dip a clean flame test sodium orange loop in the sample solution 2.hold the flame test loop at potassium lilac the edge of a bunsen burner flame 3.observe the changed colour of the flame, and decide which metal it indicates 4.clean the loop in acid and rinse with water, then repeat steps 1 to 3 with a new sample