Chemistry Notes - States of Matter PDF

Chemistry notes Chapter 1 – states of matter ​ The kinetic theory of particles states that all matter is made up of tiny particles and that these particles are in constant random motion Solid -​ Are closely packed in an orderly manner -​ Are held together by strong forces of a...

Chemistry notes Chapter 1 – states of matter ​ The kinetic theory of particles states that all matter is made up of tiny particles and that these particles are in constant random motion Solid -​ Are closely packed in an orderly manner -​ Are held together by strong forces of attraction -​ Have enough kinetic energy to only vibrate and rotate about their fixed position -​ Cannot move freely -​ The particles of a solid are very close to one another. -​ Thus a solid has a fixed shape , has a fixed volume and cannot be compressed Liquid -​ Are arranged in a disorderly manner -​ Have weaker forces of attraction than the particles of a solid -​ Have more kinetic energy than particles of the same substances in solid state , and are not held in fixed position -​ Can move freely throughout the liquid -​ The particles of a liquid are not closely packed as a solid -​ They are still very close to one another -​ Thus a liquid has no fixed shape , has a fixed volume and can compressed Gas -​ Are spread far apart from one another -​ Have weaker forces of attraction than the particles of a liquid -​ A lot of kinetic energy and are not held in fixed position -​ Can move about rapidly in any direction -​ The particles of a gas have a lot of space between them -​ They can be forced to move closer together -​ Thus a gas has no fixed shape and volume but can be compressed Change in state of matter and the kinetic particle theory Melting is the process by which a substance changes from a solid to a liquid Temperature at which a solid becomes a liquid is called a meting point What happens to particles of a solid that is heated until it melts ​ Heat energy is absorbed by the particles of the solid converting the heat energy to kinetic energy allowing the particles start to vibrate faster about their fixed position ​ When temperature is high enough , the vibrations of the particles become sufficient to overcome the forces of attraction between them , the particles begin to break away from their fixed position ​ The particles are no longer in their fixed positions and the substance is now a liquid. the particles move freely throughout the liquid  Freezing is the process by which a substance changes from a liquid to a solid The temperature at which a liquid becomes a solid is called its freezing point What happens to the particles of a liquid that is cooled until it freezes ​ Energy is given by the particles of the liquid , the particles lose kinetic energy and begin to move more slowly ​ When the temperature is low enough , the particles no longer have enough energy to move freely , the particles start to settle into fixed position ​ All the particles have settled into fixed positions thus now the substance is now solid. The particles can only vibrate about their fixed position Boiling is the process by which a substance changes from a liquid to a gas at the different boiling temperature of the substances The temperature at which a liquid is called its boiling point What happens to the particles of a liquid that is heated until its boils ​ Heat energy is absorbed by the particles of the liquid , the heat energy is converted into kinetic energy. the particles start to move faster as the temperature rises ​ When temperature is high enough energy to overcome the forces of attraction holding them together ​ The particles are now spread fart apart thus the substance is now a gas. the particles move about rapidly in any direction Differences between boiling and evaporation Boiling Evaporation Occurs only at boiling temperature Occurs at temperatures below boiling point Occurs throughout the liquid Occurs only at the surface of the liquid Occurs rapidly Occurs slowly Chapter 2 – measurement and experiment techniques Measuring mass ​ SI unit = kilogram ​ Measured with a beam balance or an electronic balance Measuring time ​ SI unit for time is the second ​ Measured using a stopwatch or stopclock Measure temperature ​ SI unit is kelvin ​ Measured using a mercury thermometer or an alcohol thermometer. a data logger could also be used but it is mainly used for outdoors Measuring volume ​ SI unit is cubic metre  Apparatus Accuracy Measuring cylinder Measures to the nearest 0.5 cm cube Burette ​ Accurately measures out the volume of liquid to the nearest 0.05 ​ Scale marked in 0.1 Pipette Accurately measures out fixed volume of liquids How to read the volume of liquid ​ Align eyes to the liquid level , at the meniscus Methods for collecting gases 1.​ Solubility – how soluble the gas is in water 2.​ Density – how dense the gas is compared to air There are 3 methods of collecting gases 1.​ Displacement of water is for gases that are insoluble or slightly soluble in water, such as carbon dioxide , hydrogen , oxygen 2.​ Downward delivery is for gases that are soluble in water and denser than air such as chlorine and hydrogen chloride 3.​ Upward delivery is for gases that are soluble in water and less dense than air such as ammonia Gas Solubility in water Density in air Method of collection Hydrogen Not Less Displacement of water Oxygen Very slight Slightly Carbon dioxide Slight Denser Chlorine Soluble denser Downward delivery Hydrogen chloride Very Denser Sulphur dioxide Very Denser Ammonia Extremely less Upward delivery Chapter 3 – separation and purification ​ A mixture is made up of 2 or more substances that are chemically combine ​ A pure substances is made up of one single element or compound. It is not mixed with any other substances  Separating a solid from a liquid Filtration ​ Filtration is used to separate insoluble solid particles from a liquid ​ A solid can be separated from a liquid by filtration because the filter paper act as a sieve ​ The solid that remains on the filter paper is the residue ​ The solution passes through the filter paper is called the filtrate Evaporation to dryness Evaporation to dryness is used to obtain a soluble solid from a solution by heating the solution until all the water has boiled off ​ The solid obtain is not always pure. When all the water has been removed , any soluble impurities will be left together with the solid Crystalizing ​ Is used for obtaining a pure solid sample from its solution ​ Decomposes when they are heated strongly ​ During crystallisation , the solution is heated until almost all the water has boiled off , a hot saturated solution. the hot saturated solution is then allowed to cool to room temperature Separating a liquid from a solution Simple distillation ​ Is used to separate a pure solvent from a liquid a solution ​ Distillation is the process of boiling point a liquid and condensing the vapour ​ In the distillation flask , boiling chips are added to ensure smooth boiling , water vapour rises and enters the condenser ​ In the condenser , water vapour is cooled. the water vapour condenses and change back into pure water ​ Pure water is collected as a distillate in the receiver ​ The solution , which remains in the distillation flask , becomes more concentrated as distillation continues until a solid residue is left Apparatus Procedure to note Reason Thermometer The bulb of the thermometer should be This ensures that the thermometer placed beside the side arm of the measures the boiling point of the distillation flask substances that is being distilled Condenser ​ The condenser should slope ​ This ensures that the pure solvent downwards, the condenser formed runs downwards into the consist of 2 tube receiver ​ Cold running water is allowed to ​ If the water enters from the top enter the water jacket from of the condenser before the water jacket can be completely  bottom of condenser and leave filled. the water , providing a from the top more efficient cooling system Receiver If the distillate is volatile ,the receiver This helps to keep the temperature of can be put into a large container filled the distillate low so that it remains in the with ice liquid state Fractional distillation ​ Is used to separate a mixture of miscible liquids with different boiling points ​ Fractionating column is attached to the round bottom flask and condenser ​ Many beads are placed in the fractionating column provided a large surface area for vapour to condense on ​ The liquid with the lowest boiling point will distil first ​ Vapour rises up the column as the solution is heated ​ The higher boiling point vapour condenses on the fractionating column and falls back into the flask ​ The lower boiling point distils over first ​ The thermometer will show a constant temperature of the vapour ​ In the condenser , the vapour cools and condenses , the liquid flows down inside the condenser and into the receiver ​ The liquid is than collected as the distillate in the receiver ​ When 1 has been distilled over , the temperature rises to the next vapours temperature and the water distils will be collected separately Chromatography ​.is the method of separating two or more components that dissolve in the same solvent ​ Used to separate the components in a sample , identify the components present ​ Identify substances ​ Determine if the sample is pure Chapter 4 – elements , compounds , mixtures ​ An element is a pure substances that cannot be broken down into 2 or simpler substances by chemical process ​ Atoms are the smallest particles of an element that have chemical properties of that element ​ Molecule is a group of 2 or more atoms that are chemically combined ​ A compound is a pure substance containing 2 or more elements that are chemically combined in a fixed ratio ​ A compound has different properties from the elements that form it ​ A mixture is made up of 2 or more substances that are not chemically combined Mixture Compound Separation Can be separated by physical Can be broken down into its properties elements or simpler compounds by chemical process Properties Chemical properties are the same Physical and chemical as its components properties are different from its elements Energy change No chemical reaction A chemical reaction takes place Composition Can be mixed in any ratio Combined in a fixed ratio Chp 5 – atoms Protons ​ Has a relative charge of +1 ​ Has a relative mass of 1 ​ Tightly packed in the centre of an atom to form the nucleus Neutron ​ Has a relative charge of 0 ​ Has a relative mass of 1 ​ Tightly packed in the centre of an atom to form the nucleus Electron ​ Has a relative charge of -1 ​ Has a relative mass of 1/1840 ​ Moves rapidly around the nucleus ​ The number of electrons is the same as the number of protons , thus the negative charges cancel out the positive charge leading the atom to be electrically neutral ​ The proton number is also called the atomic number ​ From the proton number the no of electrons can be determined ​ The nucleon no of an atom is the total number of protons and neutrons in the atom ​ Mass no = nucleon no ​ When representing , nucleon no on top left and the proton no left bottom and the symbol on the right Isotopes ​ Isotopes are atoms of the same element with the same number of protons and electrons but with different number of neutrons The same number of protons and electrons Different numbers of neutrons  ​ Chemical reactions involve only the ​ Physical properties are affected by electrons and not the neutrons mass ​ Similar chemical reactions ​ Different mass and have different physical properties Both chlorine-35 and chlorine-37 react with Hydrogen-2 has a slightly higher boiling sodium to produce sodium chloride point and density than hydrogen-1 Arrangement of electrons in atoms First shell ​ Is close to the nucleus ​ Corresponds to the lowest energy level ​ Can hold a max of 2 electrons ​ Is always filled first followed by the Second and third shells ​ Have increasing energy level ​ Usually hold up to eight electrons each ​ Are filled in order – usually , the second shell is fully filled before the third shell ​ The valence shell or outer shell of an atom refers to shell that is furthest away from the nucleus of the atom Chp 6 – chemical bonding ​ Noble gases (last column ) do not react with other elements or form compounds , they exist as monatomic and exists as individual atoms ​ Noble gases are unreactive and stable ​ Atoms of most other elements are reactive , they combine with other atoms to form molecules or compounds ​ Either a duplet electronic configuration or octet electronic configuration ​ To achieve the electronic configuration of a noble gas , the atoms do it by losing outer electrons or gaining outer electrons or sharing of outer electrons Forming ions ​ Metals form positively-charged ions ( cations ) ​ Non-metals form negatively-charged ions ( anions ) ​ Positive ions or cations are formed when atoms lose electrons ​ Negative ions or anions are formed when atoms gain electrons Ionic bonding : transferring electrons ​ Ionic bonds are strong electrostatic forces of attraction between positive and negative ions ​ Using dots to represent the electrons of 1 atoms ​ Crosses represent the electrons of the other atom  Ionic bonding : physical properties non metal & metal Most ionic compounds have high melting points and high boiling point ​ Forces of attraction between the oppositely charged ions are strong. A large amount of heat energy is needed to overcome these strong attractive forces to melt the ionic compound Ionic compounds are usually soluble in water and insoluble in organic solvent ​ Ionic compound are soluble in water , as water weakens the forces of attraction between the ions. as a result , the ions are pulled from the lattice structure and the compound dissolves to form an aqueous solution ​ Insoluble in water there is no water present leading the ionic compounds to remain tightly held in the lattice structure Ionic compound conduct electricity when molten or in aqueous solution ​ When an ionic compound is molten or dissolved in water it can conduct electricity as the free-moving ions or electrons in order to conduct electricity , when the ions are molten or dissolved the cations and anions are free to move and are available to conduct electricity ​ Ionic compounds do not conduct electricity in the solid state as there are no-free moving ions to conduct electricity in the solid state since the ions are held in place in the lattice structure Covalent bond : sharing electrons non-metal & non metal ​ Covalent bond is a bond formed by the sharing of electrons between 2 atoms Physical properties 1.​ Most covalent substances with simple molecules have low melting and boiling point 2.​ Covalent substances are usually insoluble in water but soluble in organic solvent 3.​ Most covalent substances don’t conduct electricity whether in the solid , liquid or gaseous state Chp7- writing chemical equations ​ A balanced chemical equation must contain a equal no of atoms of each element on both sides of the equation ​ The reactants are on the left side while the products are written on the right side of the equation ​ An ionic equation shows the ions that take part in a reaction it leaves out the spectator ions that don’t react ( cancel out the aqueous ones like separate them out ) Chp 8 – chemical calculations ​ Mass units is grams ​ the formula is mass / number of moles of substances multiply relative formula mass ​ relative molecular mass is taking the nucleon no ( no units ) - Square is multiply by 2 - add them up ​ mole mass will be given in the qn ( no units ) Chp 9 – acids and alkalis Acids 1.​ Substances that produces hydrogen ions in aqueous solution 2.​ salts are called - sulfates when they are formed with sulfuric acid - Nitrate when they are formed with the nitric acid - Chlorides when they are formed with hydrochloric acid 3.​ Properties of acid - sour taste - dissolve in water to form solution which conducts electricity - turns blue litmus paper red - acid reacts with reactive metals to form a salt and hydrogen gas Metal + acid = salt + hydrogen ( during a reaction , bubbles of hydrogen gas can be seen ) - acids reacts with carbonate and hydrogen carbonates to form a salt , water and carbon dioxide gas Carbonate + acid = salt + water +carbon dioxide - acids react with metal oxide and hydroxides to form a salt and water only Metal oxide + acid = salt + water Which metals do no react with acid - unreactive metals such as copper or silver are added to dilute acids as there is no reaction Lead appears not to react with dilute hydrochloric acid as a layer of lead (ll) chloride is produced and this layer is insoluble in water and quickly forms a coating around the metal What is the role of water in acids - acids only display their properties when they are dissolved in water as acids produces hydrogen ions only in water as the hydrogen ions give acids their properties Bases and alkalis 1.​ Base is any metal oxide or hydroxide that reacts with an acid to produce a salt and water only 2.​ The general equation , base + acid = salt + water Alkalis are a special class of base 3.​ In a neutralisation reaction , the hydrogen ions from the acid and the hydroxide ions from alkalis react to form water 4.​ An alkali is a substance that produces hydroxide ions in aqueous solution 5.​ Properties of alkalis - bitter taste and feel soapy - turn red litmus paper blue - reacts with acids to form a salt and water only - alkalis when heated with ammonium salts , cause ammonia gas to be given off Alkali + ammonium salt = salt + water + ammonia The pH value - acids have pH value less than 7 and have a higher concentration of hydrogen ions - alkalis have pH greater than 7 and have a higher concentration of hydroxide ions - a neutral solution has a pH value of exactly 7 How to measure PH value of a given solution Universal indicator , methyl orange Indicator Colour in acidic pH range @ Colour in alkaline solution indicator solution changing colour Methyl orange Red 3-5 Yellow Screened methyl Violet 3-5 Green orange Litmus Red 5-8 Blue Bromothymol blue Yellow 6-8 Blue Phenolphthalein Colourless 8-10 Pink Why is the pH of s soil important - most plants will not be able to grow below 5 or above 9 - most plants grow best when the soil is neutral or slightly acidic 1) the pH of soil may become 2) environmental pollution such as acid rain  Types of oxide Acidic oxides 1.​ Non-metal 2.​ Most acidic oxides dissolve in water to form acidic 3.​ Acidic oxides do not react with acids. however , they react with alkalis to form a salt and water Basic oxides 1.​ Metal 2.​ Most basic oxides are insoluble in water 3.​ A few oxides such as sodium oxide dissolve readily in water to form alkalis 4.​ Basic oxide are solid at room temperature , react with acids to form a salt and water Amphoteric oxide 1.​ Metallic oxide that reacts with both acids and bases to form salts and water 2.​ Zinc and example behaves as a basic oxide and acidic oxide as salt and water are formed Neutral oxide 1.​ Some non-metals form oxides that show neither basic nor acidic properties and they are insoluble in water 2.​ Examples are water , carbon monoxide and nitric oxide Chp 10 – salts 10.1 ​ Salts contain ionic compounds – containing cation and anion ​ Salts can be made by reacting acids with metals , carbonates , bases or alkalis Reactants Products Acids + metal Salt + hydrogen Acid + carbonate Salt + water + carbon dioxide Acid + base / alkali (neutralisation) Salt + water ​ During the reaction, one or more hydrogen ions of acids is replaced by a metal ion or an ammonium ion  Water of crystallisation ​ Salts containing water of crystallisation are hydrated salts ​ When hydrated salts are heated, the water of crystallisation is given out ​ Salts that do not contain water of crystallisation are anhydrous salts Name of salt Formula for anhydrous salt Formula for hydrous salts Copper (ll) sulfate Magnesium sulfate Sodium carbonate Zinc sulfate Soluble and insoluble salts ​ Not all salts are soluble in water , the solubility of a salt must be determined before we can choose a suitable method for preparing the salt Soluble salts Insoluble salts All sodium salt All potassium salt All ammonium salt All nitrates salt All chlorides Silver chloride Lead (ll) chloride All sulfates Barium sulfate ( BLC ) Lead (ll) sulfate Calcium sulfate Sodium carbonate ( SPA) Potassium carbonate All carbonates Ammonium carbonate 10.2 – preparation of salt ​ Salt is soluble use the reaction with acids ​ Salt is soluble use the precipitation method Method 1 ( soluble salts ) In this method , the metal , base or carbonate ​ Must be in excess so that all the acid is used up otherwise the salt produced will be contaminated with the acid ​ In soluble in water , thus the excess starting materials can be removed from the salt solution by filtration ​ This method is no suitable for some metals due to very reactive metals potassium , sodium , calcium. these react violently causing it to be very dangerous. there r unreactive metals - copper , sliver ​ If metals is reactive or unreactive , it can be prepared by reacting with an acid with the insoluble base or carbonate instead How to prepare salt by reacting an acid with an insoluble base -​ By using copper(ll) oxide + dilute nitric acid = copper(ll)nitrate +water -​ Add dilute nitric acid with excess copper (ll) oxide to form copper(ll)nitrate solution + copper(ll) oxide (unreacted) than filter and collect the filtrate (copper ll nitrate solution ) crystallise and filter to get copper(ll) nitrate crystals How to prepare a salt by reacting an acid with an insoluble carbonate -​ Reacting magnesium carbonate with hydrochloric acid Method 2 – titration Acid + alkali = salt + water Acid + soluble carbonate = salt + water + carbon dioxide gas -​ All starting materials used are soluble ( the volume of each starting materials must be exact as the excess cannot be removed from the salt solution by filtration and the salt produced will be impure ) -​ To determine exact volumes of reactants use titration -​ Titration is using a burette by rinsing it with water and alkali (sodium hydroxide). Than using a pipette measure the volume of acid using a suction. Put the measured acid into a conical flask adding 2 drops of methyl orange and placed a white tile under the flask. Using a retort stand put a burette filled with sodium hydroxide. slowly drip alkali into the conical flask with acid slowly swirl until its orange ( neutralisation has occurred ) Method 3 ( insoluble salt) – precipitation -​ Involves mixing 2 solutions to form an insoluble solid that separates out from the reaction mixture -​ To produce the insoluble salt , mix solution containing the cation of the salt with solution containing the anion of the salt -​ Preparing barium chloride n magnesium sulphate 1.​ Pour barium nitrate solution into a beaker , add solution sulphate solution in excess and stir until no more precipitation forms 2.​ Filter to collect the precipitate as residue 3.​ Wash the precipitate with a little distilled water to remove soluble impurities 4.​ Allow the precipitate to dry on a piece of filter paper Name of salt Reagent 1 Reagent 2 Silver chloride Silver nitrate Barium chloride Lead(ll) chloride Lead (ll) nitrate Hydrochloric acid Sodium carbonate Lead(ll) sulfate Lead(ll) nitrate Sulfuric acid Sodium sulfate Identifying gases Gas Colour n odour Test Observations Hydrogen Colourless n Place lighted The lighted splint odourless splint at the is extinguished mouth of the with a pop sound test-tube Oxygen Colourless n Insert a glowing The glowing splint odourless splint into the is rekindled test tube Carbon dioxide Colourless n Bubble of gas A white odourless though lime precipitate is water formed The precipitation dissolves upon further bubbling Ammonia Colourless gas n Place a piece of The moist litmus pungent smell moist litmus paper turns blue paper at the mouth of the test tube  Chp 11 – metals ​ metals and alloys ​ 1. metals are characterised by normally being shiny , strong solids with high melting points , which are goods conductors of heat and electricity ​ 2. metals have high densities , melting points and boiling points as the atoms are packed tightly in layers and held together by strong metallic bonds requiring a large amount of energy is required to break these bonds ​ 3. metals are malleable and ductile because their atoms are of the same size and are closely packed in neat layers. when a force is applied , the layer slide easily over one another Alloys 1.​ The properties of a particular metal can be improved if it is mixed with another element 2.​ Compared to pure metals , alloys are harder and stronger having a better appearance and lower melting points and are more resistant to corrosion 3.​ The atoms of a metal are arranged in regular pattern. however if another element is added this prevents the atoms from sliding over one another , thus alloys tend to be harder and stronger than pure metals 4.​ Zinc is added to copper formed is much stronger than pure copper 5.​ Another alloy of copper is bronze which consist of copper and thin , the presence of tin makes the copper harder and less likely to corrode ​ Why r alloys stronger n harder than their constituent metals ​ The atoms of different metals or elements have different sizes. The atoms of different sizes cannot slide over each other easily when a force is applied the reactivity series Potassium Please Sodium Send Calcium Camels Magnesium Monkeys Zinc Zebra Iron In Lead Large Hydrogen Heavy Copper Crates Silver Soon Reactions of metals with cold water Potassium Reacts violently hydrogen gas catches fire and explodes Sodium Reacts violently hydrogen gas may catch fire and explode Calcium Reacts readily Magnesium Reacts very slowly No reaction Zinc iron lead copper silver Reaction of metals with steam Potassium Reacts explosively Sodium Reacts explosively Calcium Reacts explosively Magnesium Reacts violently to produce a white glow Zinc Reacts readily when hot its yellow and when its cold its white Iron Reacts slowly No reaction Lead copper silver Reaction of metals with hydrochloric acid Potassium Reacts explosively Sodium Reacts explosively Calcium Reacts violently Magnesium Reacts readily Zinc Reacts moderate fast Iron Reacts slowly No reaction Lead copper silver Conclusion Metals Reaction w cold water n Reaction w dilute stem hydrochloric acid Potassium Violently Explodes Sodium Calcium Readily w cold water n Violently explodes w stem Magnesium Slowly w cold water n Readily violently w stem Zinc No reaction w cold water Readily n readily w stem Iron No reaction w cold water Slowly n reacts slowly w stem Led No reaction No reaction Copper Silver Extracting metals The methods 1.​ Heating the compound/ore with carbon 2.​ Electrolysis – using electricity to decompose the molten metals compound/ore to the metal Potassium Extracted by electrolysis Sodium Calcium -​ Metals high up in the Magnesium reactivity series r reactive -​ Compounds r very difficult to be broken down -​ Only be extracted using electricity Zinc Extracted by heating metal oxide w Iron carbon Led -​ Placed in the middle of the Copper reactivity series r not so Silver reactive -​ r readily extracted by heating their oxide with carbon Gold Found naturally uncombined Extracting of metals from hematite -​ contains iron(lll) oxide w impurities -​ done in blast furnace 1.​ carbon dioxide is produced -​ the carbon in coke burns blast of hot air , this reaction produces lots of het 2.​ carbon monoxide is produced -​ carbon dioxide rises up the furnace , it reacts w more coke to form carbon monoxide 3.​ hematite is reduced to iron -​ the carbon dioxide reduces the iron(lll) oxide in hematite to iron -​ the iron formed is molten n runs to the bottom of the furnace 4.​ impurities r removed -​ limestone is decomposed by het to produce carbon dioxide n calcium oxide -​ calcium oxide is basic oxide , reacts w silicon dioxide which is acidic w other impurities in hematite to form molten slag -​ hot waste gases containing carbon monoxide , carbon dioxide n nitrogen escape through the top of the furnace. it floats on top of molten iron. the slag n iron r topped off separately  rusting -​ the presence of both oxygen n water r necessary for rusting to occur -​ iron + oxygen + water = hydrated iron(lll) oxide -​ the presence of sodium chloride/ acidic substances increases the speed of rusting Prevention of rusting -​ need to be kept from water n oxygen so iron r coted w painting or grease , plastic n electroplating electroplating involves another layer of another metal Method Where is it used Dis/advantages Painting Large objects like ships If its scratch on the metal surface , rusting will take place under the painted surface Oiling or grease Tools n machinery The protective film of oil or grease gathers dust must be renewed Plastic coting Kitchenware – draining racks If its torn , rusting occurs Tin-plating Food cans Tin layer scratched , the iron starts to rust Chrome-plating Kettles , bicycle This gives bright shiny finish ​ ​ ​ Recycling metals 1.​ good of recycling metals ​ recycling helps to conserve natural resources – helps to conserve our limited fossil fuel reserves ​ recycling helps to reduce environmental problems related to extracting metals from their ores - mined land can’t support plant life if not disposed properly , polluting land , water n ir ​ recycling saves the cost of extracting metals from their ores – huge landfills sites r dug up to dispose the waste from the metals. with more metals being recycled means that fewer landfills = saving the cost of building Issues related to recycling 1.​ economic issues -​ cost of transport the scrap metal to the processing plant  -​ different types of metals must be separated before recycling requiring more cost to be incurred to sort n cleaning the scrap -​ recycling is sometimes more expensive than extraction leading to some thinking that recycling is not worthwhile 2.​ social issues – takes time n effort for communities to adopt recycling part of lifestyle , it might not be immediately effective 3.​ environmental issue – cause pollution problems = led in car batteries that no longer work , when they r melted it releases harmful gases chp 12 - the periodic table -​ the periodic table is list of elements arranged in order of increasing proton number -​ group = vertical column of elements -​ period = horizontal row of elements -​ extreme left is metals to metalloids to non-metals -​ from left to right cross period , there is decrease in metallic properties n increase in non-metallic properties -​ the number of electron shells is the same the period number -​ the number of valence electrons is the same the group of the element group l elements – alkali metals 1.​ physical properties -​ soft n cut easily -​ low melting n boiling point -​ low densities , lithium , sodium n potassium float on water 2.​ how do the properties change going down -​ melting points n boiling points of alkali metals decreases -​ the densities of alkali metals generally increases 3.​ chemical properties of alkali metals -​ highly reactive metals thus they r stored in oil to prevent –from reacting w air n water do alkali metals have the same reactivity ​ -​ reacts w cold water to form alkali n hydrogen alkali metal Observation n equation for reactions w water ​ Lithium Reacts quickly n floats on water Lithium + water = lithium hydroxide + hydrogen  Sodium Reacts violently. sodium drts round the water surface it can be explosive Sodium + water = sodium hydroxide + hydrogen Potassium Reacts very violently making it explosive Potassium + water = potassium hydroxide + hydrogen -​ alkali metals form ionic compound group vll elements – halogens 1.​ physical properties -​ non-metals that exist diatomic covalent molecules -​ low melting point n boiling point -​ they r coloured 2.​ physical properties of halogens going down -​ melting points n boiling points increases -​ colours become darker 3.​ chemical properties -​ halogens r reactive non-metals -​ halogens react w most metals to form salts halides -​ halogens undergo displacement reactions w halide solutions 4.​ reactivity order -​ decreases down the group because the size of the tom increases down the group making it more difficult for the nucleus to attract one more electron group 0 elements – noble gases 1.​ properties of noble gases -​ no-metals -​ monatomic -​ colourless gases room temperature -​ low melting n boiling points -​ insoluble water 2.​ why r noble gases unreactive -​ they either have 2 or 8 valence electrons. their full structure makes them unreactive , they don’t lose , gin or share electron  chp 13 air composition of air 1.​ consist of several gases ( both elements n compounds ) n is mixture 2.​ Min gases r nitrogen 78% n oxygen 21% with the rest being noble gases. the mount of water vapour depends on the location 3.​ air can be separated by fractional distillation of liquid ir pollution 1.​ air pollution is the condition in which ir contains high concentration of chemicals that my harm living things or damage non-living things 2.​ carbon monoxide – it comes from the incomplete combustion of petrol in engines 3.​ sulfur dioxide – when fossil fuel is burnt in power stations n factories , the sulfur present will be converted to sulfur dioxide - sulfur dioxide is produced in large quantities during volcanic eruptions Common air pollutants 1.​ oxides of nitrogen – found in engines or chemical factories where temperature r high n nitrogen n oxygen combine - during thunderstorms , het energy released by lightning causes nitrogen n oxygen in the air to react to form oxides like nitrogen monoxide n nitrogen dioxide 2. unburnt hydrocarbons , methane n ozone - released in exhaust fumes n chemical plants - methane is produced when plant n animal decay , sheep n cow give off methane due to the digestion of food , from the decay of rubbish in landfills - ozone is formed when nitrogen dioxide in the air reacts with unburnt hydrocarbons in the presence of sunlight ​ Effects of air pollutants air pollutant Effects Carbon monoxide ​ reacts with haemoglobin in blood which reduces the ability of haemoglobin to transport oxygen to the rest of the body ​ causes headache , fatigue , breathing difficulty n even death Sulfur dioxide , oxides of nitrogen ​ irritate the eyes n lungs causing breathing difficulties ​ react w water in the atmosphere to form acid rain which corrodes buildings n harms aquatic life n plants acid rain 1.​ form when acidic air pollutants ( sulfur dioxide n nitrogen dioxide ) react with water in the atmosphere 2.​ the Ph. Value of unpolluted water is slightly below 7 due to carbon dioxide in the ir dissolving in rainwater to form carbonic acid which is weak acid 3.​ acid rain ph. value of less than 4 what r the effects of acid rain on buildings , plant n aquatic life - sulfur dioxide n oxide of nitrogen r released into the atmosphere n react w water to form acid rain - acid rain reacts with metals n carbonates n damage them - leeches nutrients from soil n cause plants to wither n die n the PH value is to acidic n will kill is fish Chp 14 – organic chemistry ​ all organic compounds contain the element carbon n most contain hydrogen ​ Only hydrogen n carbon r called hydrocarbons ​ Organic compounds contain other elements such as oxygen , chlorine n nitrogen ​ Homologous series is a family of organic compounds with same functional group n similar chemical properties ​ Functional group is an atom or group of atom that gives a molecule its characteristics properties ​ Alkanes – do not have functional group , there r only C-C n C-H bonds ​ Alkenes – C=C , carbon-carbon double bond General characteristics of homologous series ​ Organic compounds in the same homologous series have the following characteristics ​ Same functional group  ​ Similar chemical properties ​ Gradual change in their physical properties as we go down the series from one member to the next Naming the compounds Prefix Meth- Eth- Prop- But- Number of carbon atoms/ molecule One Two Three Four Suffix -ane -ene Homologous series Alkane Alkene Petroleum n natural gas - Petroleum is naturally occurring mixture of hydrocarbons Refer to the slide