Unit 22 Elements, Molecules And Compounds

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Unit 22

Elements, Molecules and Compounds

That elements are pure substances, containing only one type of atom.

That elements are arranged in the periodic table according to their atomic number giving rise to eight distinct groups of elements with similar physical and chemical properties.

The nature of sub atomic structure and that all atoms consist of protons, neutrons and electrons.

The electronic configuration of the first 20 elements.

The nature of materials and their properties.

That molecules and compounds consists of two or more atoms of different or same elements.

The relative formula mass of molecules and compounds.

That mass cannot be destroyed or created during chemical reactions.

Element, Atoms, Particles, Protons, Neutron, Electron, Periodic, Table, Groups, Periods, Materials, Molecules, Compounds, Orbital, Shells, Isotopes, Relative, Atomic, Mass, Formula & Conservation. Unit 22: Elements, Molecules and Compounds web: www.science-interactive.co.uk email: sales@science-interactive.co.uk Science Interactive LTD PO BOX 50764 LONDON NW6 9AT Click mouse to begin Science Interactive LTD Copyright 2005 Understand: Keywords:

Understanding materials one All materials, c___________ or chemicals are made from matter or atoms of elements. There are just over 100 elements in the periodic table that combine together in different ways to give rise to all the different types of materials that we use and see every day. Some materials are extremely simple, containing only one or two different e__________, where as others like biological molecules contain many different types of elements. What is the definition of a pure substance ? Materials and what they contain: Science Interactive LTD Copyright 2005 Word bank: compounds elements Diamond, the hardest known substance is made from one type of element: Carbon Diamond Water, without which life would not exist is made from two elements: Hydrogen and Oxygen Water Notes Diagram Sand found on beaches everywhere is made from two elements: Silicon and Oxygen Sand Humans contain many thousands of complex molecules, made from the following elements: Hydrogen, Iron Oxygen Carbon, Nitrogen & Phosphorus Human

Understanding materials two Atoms of different elements found in the p_________ table are the building blocks of all materials. There are over 30 million materials made from just over 100 elements. In iron, all the atoms are the same, because iron is an element. In a material like steel, all the atoms are not the same. Steel contains iron atoms, carbon atoms and other metals atoms like chromium and nickel. Iron, the pure element is like any other metal, but it rusts, combining readily with o________ and water. Steel which does not rust is also much stronger. That’s why we use the majority of iron for making steel. What is a metal alloy and give two examples ? Materials and what they contain: Science Interactive LTD Copyright 2005 Word bank: periodic oxygen Tungsten extracted from tungsten oxide is a pure element containing only one type of atom: Tungsten Tungsten Glass a transparent non absorbent material used in windows and glasses contains the elements: Calcium oxygen & silicon. Glass Notes Diagram Iron extracted from iron ore is a pure element containing only one type of atom: Iron. Iron Steel is stronger and more rust resistant than iron because it also contains the elements: Iron, Carbon, Nickel & Chromium. Steel

Understanding materials three The combination and ratio of e_________ that are found in materials like glass, fibres, ceramics or plastics determines all their physical properties. These properties include its colour, whether it is hard, dense or soft, whether it has a high or low melting point or even whether the material is a good or poor conductor of h_____ and electricity. These properties make the material useful for a particular function. There are over 50 metals naturally occurring, list their properties and explain why they’re very useful elements ? Materials and what they contain: Science Interactive LTD Copyright 2005 Word bank: elements heat Computer chips made by companies like Intel form the central part of the computer contain only one type of atom: Silicon Computer chips Earth's atmosphere which insulates us, allows respiration and protects us from UV rays contains the following elements: Oxygen, Nitrogen & Noble gases. Atmosphere Notes Diagram Gold found and extracted from river beds is a pure element containing only one type of atom: Gold Gold Plants contain many thousands molecules which contain the following elements: Hydrogen, Iron Oxygen Carbon, Nitrogen & Phosphorus Plants

The periodic table one Elements in the periodic table are arranged by their atomic number which is determined by the number of p________ each element contains. Using this rule, gives rise to groups of elements with similar chemical and physical properties. There are eight distinct groups of elements, for example group one elements are the reactive alkaline metals. There are also 30 elements known as the transitional metals . There are five periods or rows. Each element has its own unique s__________ which is used all over the World to save time. Find the symbols for the following elements: Sodium, Gold, Iron, Oxygen, Nitrogen and Neon ? The periodic table: C 6 12 Atomic mass Symbol Atomic number Each element has its own symbol, atomic number and atomic mass. The symbol for each element is unique. This is not always the first letter of the element. Science Interactive LTD Copyright 2005 Word bank: protons symbol There are over 100 elements in the periodic table. There are eight groups, the transitional metals and five periods or rows in the periodic table. Each vertical group of elements have very similar chemical and physical properties because of their similar electronic configuration (electrons in shells) Describing elements The periodic table (Look at the metallic, non metallic and semi metallic elements)

The periodic table two Each element in the periodic table has its own very different properties. Metals and non-metals have very different uses and p__________. Metals like copper, aluminium, zinc and iron are hard, shiny, dense, malleable, ductile, conductive of heat and electricity. Non-metals like carbon and sulphur usually have the opposite properties. They are d______, soft, brittle and poor conductors of heat and electricity. Are there any exceptions to these general properties for metals ? Metals in the periodic table: Science Interactive LTD Copyright 2005 Word bank: properties dull Lithium is an extremely soft and reactive metal. Although it cannot be used like iron or copper it is used in batteries like the one pictured here. Lithium Gold has a high monetary value and is used to make jewellery. Governments use gold to guarantee their paper currencies. Gold Aluminium with its high strength to weight ratio is used in planes and bike frames. It is also a safe material to store fizzy drinks. Aluminium Iron is used to build complex machines and super structures like the French Eiffel tower. Corrosion can be a problem. Iron

The periodic table three Most of the elements in the periodic table are metals, but what about the non metals. Some are solids like carbon and sulphur, some are liquid like b________, but most are gases like nitrogen, oxygen and chlorine. Carbon is found in all fuels and biological molecules. Many of the gaseous elements are found in our atmosphere, for example o_______ which is essential for respiration and combustion of compounds containing carbon. The halogens including chlorine and iodine all have antiseptic properties. The Noble gases which includes helium are a family of un-reactive gases. Are there any exceptions to these general properties for non metals ? Non metals in the periodic table: Science Interactive LTD Copyright 2005 Word bank: bromine oxygen Neon atoms Hydrogen molecules Carbon atoms Carbon atoms Notes Hydrogen Neon Notes Diagram Element Carbon (Diamond) Carbon (Graphite)

Elements one Each element has an internationally recognised symbol and unique atomic and mass number . Atoms of different elements like sodium (reactive group I metal) and chlorine (reactive group VII non metal gas) are all made from three identical sub atomic particles. Elements are made from e_________ , protons and neutrons . The only difference between elements is the number of each sub atomic particle. Therefore, the number of electrons, protons and neutrons each element contains determines all their physical and chemical properties . What makes a reactive metal like s_______, simply 11 electrons and protons and 12 neutrons. What makes a reactive gas like chlorine, simply 17 electrons and protons and 20 neutrons and that’s it !! Elements : Science Interactive LTD Copyright 2005 Word bank: electrons sodium Sulphur atoms Oxygen molecules Gold atoms Mercury atoms Notes Sulphur Oxygen Particle diagram Diagram Mercury Gold

Elements two Elements in the periodic table exist in eight vertical g________. There are also 30 metals which are known as the transitional metals. Elements in the same group have the same number of electrons in their outermost shell. They also have very similar physical and chemical properties. The halogens located in group VII are all reactive non metals, with general antiseptic properties: Fluoride in toothpaste, Chloride in s____________ pools and Iodide for skin prior to surgery. Find out about the group I metals (alkaline metals) or the group VIII Nobles gases. Do they have similar chemical and physical properties ? Elements : Fluorine Bromine Iodine 9P + 9N 9E - Chlorine 17P + 17N 17E - 35P + 35N 35E - 53P + 53N 53E - F Cl Br I 9 17 35 53 Science Interactive LTD Copyright 2005 Word bank: groups swimming The halogens all have seven electrons in their outermost shell. They exist as diatomic molecules and can form new compounds with other non-metals or metals. They are used for their antiseptic qualities. Iodine Bromine Chlorine Fluorine The halogens

Molecules one In some elements like nitrogen and oxygen, the atoms pair up. A particle that consists of more than one atom is called a m_________. All the group VII halogens: Fluorine, Chlorine, Bromine and Iodine also pair up in molecules. We can show how many atoms a molecule contains by using a chemical formula . Oxygen for example, consists of two oxygen a______ with the formula O 2 . Nitrogen contains two nitrogen atoms with a formula of N 2 . Write down the formula of fluorine, chlorine, bromine & iodine ? Molecules of elements: N N O 2 N 2 H 2 O 3 Science Interactive LTD Copyright 2005 Word bank: molecules atoms Ozone is made from three atoms of oxygen and is found in the top layers of our atmosphere. Without ozone, UV light would prevent all life from surviving. Ozone Hydrogen is not found on its own. It is bound to other elements in compounds like water. Hydrogen is also the fuel of our own Sun in the solar system. Hydrogen Notes Diagram Oxygen found in our atmosphere is used during respiration by all cells. Oxygen is produced by green plants during photo-synthesis. Oxygen Nitrogen is found in our atmosphere and makes up nearly 79% of it. It is inert in this form but in nitrates it is absorbed and used by plants to build proteins. Nitrogen

Molecules two Molecules containing more than one type of atom are the building blocks of all compounds. In a compound, the atoms of different elements are chemically b________ together. Water for example, is a compound made up from two elements; hydrogen and oxygen . We can represent how many atoms of each element and how they are joined to each other using a chemical formula or a particle diagram. Ammonia the compound, has a formula NH 3 . This tells us that a single ammonia molecule contains three atoms of h_________ joined to one atom of nitrogen. Molecules of compounds: HCl H 2 0 NH 3 CH 4 S0 2 Science Interactive LTD Copyright 2005 Word bank: bonded hydrogen Methane, a fossil fuel is removed from underneath the rock. Methane is combusted with oxygen. Methane Sulphur dioxide is emitted as a pollutant during the combustion of fossil fuels like petrol. Sulphur dioxide Ammonia is made during the Haber industrial process and is an important starting compound for fertilisers. Ammonia Water is called and known as the molecule of life. It is essential for all life to exist here on Earth. HCl is used in laboratories and is also found in the stomach. The HCl Acid helps protein digestion. Notes Diagram Hydrochloric acid Water

Compounds one There are over 30 million different materials or compounds. These are made from just over 100 elements. These elements must join up in different ways. We can show what a compound is made from by knowing its f__________. The formula tells us the type of atoms and how many of them we find in the simplest unit of a compound, a molecule . Compounds can be very simple like sodium chloride and water or very complex like most biological molecules . These molecules, found in cells like p_________ or even DNA are very complex and can have as many as 100,000 atoms in a single molecule. Simple and complex compounds: Simple Simple Complex Complex Science Interactive LTD Copyright 2005 Word bank: formula proteins Carbon, Oxygen, Hydrogen & Nitrogen Carbon, Oxygen, Phosphorus, Hydrogen, Sulphur & Nitrogen Carbon, Oxygen & Hydrogen Sodium & chlorine Contains Protein DNA Notes Diagram Sodium chloride Methanol

Compounds two A compound contains two or more types of a_______ joined together by a chemical bond. The particles in a compound are known as molecules. Compounds always have a formula which always tells us which and how many e__________ they are made from. There are millions of compounds all made from elements found in the periodic table. In the table we will examine the following compounds: Sand, Water, Methane and Glucose. Simple compounds and their formulae: Science Interactive LTD Copyright 2005 Word bank: atoms elements C 6 H 12 O 6 CH 4 H 2 O SiO 2 Formula Glucose Methane Diagram Picture Sand Water

Compounds three Knowing and understanding compounds and their many formulae, allows us to understand what happens to elements and molecules during a c_________ reaction. During photosynthesis for example, water and carbon dioxide are combined in the leaf to make glucose and oxygen . Glucose contains the elements carbon , hydrogen and oxygen found in the starting substrates, carbon dioxide and water . A single molecule of glucose contains 6 atoms of carbon, 12 atoms of hydrogen and 6 atoms of o_________. Its formula is therefore C 6 H 12 O 6 . We can see a single molecule of glucose, but many millions or even billions make up a single glucose crystal. Photosynthesis in green plants: Science Interactive LTD Copyright 2005 Word bank: chemical oxygen C 6 H 12 O 6 6O 2 6CO 2 6H 2 O Plant Chloroplast Light energy leaf During photosynthesis in green leaves, a single molecule of glucose and six molecules of oxygen are made from combining six molecules of carbon dioxide and six molecules of water. Light energy is used to break the bonds between the atoms of carbon dioxide and water. When glucose molecules are formed, they are then taken to the rest of the plant and then used in cellular respiration or combined with more glucose molecules to form starch, a polymer of glucose. All producers are able to combine CO 2 and H 2 O during photosynthesis producing glucose. Cellular photosynthesis equation: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon dioxide Water Glucose Oxygen Diagram Notes Inside the leaf

Relative atomic mass one Each e_________ in the periodic table has a unique atomic number and relative atomic mass. We can use the atomic number and mass number to build a complete picture of an atom. The atomic number of an atom tells us the number of protons found in element’s nucleus. Subtracting the atomic number from the m______ number gives the number of neutrons. In an uncharged element the number of protons equals the number of electrons. Work through the four examples below, giving the number of neutrons, protons and electrons ? Atomic mass: Lithium Carbon Oxygen 3P + 4N 3E - Calcium 6P + 6N 6E - 8P + 8N 8E - 20P + 20N 20E - Seven Twelve ____________ ? ____________ ? Three Six _____________ ? ____________ ? Science Interactive LTD Copyright 2005 Word bank: element mass Li 3 7 C 6 12 O 8 16 Ca 20 40 Atomic Number Calcium Oxygen Mass Number Diagram Element Lithium Carbon

Relative atomic mass two Single atoms have a very s_______, almost negligible mass. The mass is so small that it makes it impossible to use in calculations. Instead, an element’s mass is compared with other elements. Relative atomic masses has been calculated for all elements, so that we can compare the mass of one element relative to another. For example: hydrogen has a mass of one on this scale, h________ is four times heavier, at four. Carbon is twelve times heavier, at twelve. Link the relative atomic mass of an element with the number of protons and neutrons that each element contains. Why do electrons appear not to contribute to the mass of an element ? Comparing masses of elements: Hydrogen Helium Carbon 1P + 1E - Magnesium 12P + 12N 12E - 6P + 6E - 6N 2E - 2N 2P + one four twelve twenty four Science Interactive LTD Copyright 2005 Word bank: small helium H 1 1 He 2 4 C 6 12 Mg 12 24 Hydrogen Equivalents Twenty four Magnesium Twelve Carbon Mass Number Diagram Element One Hydrogen Four Helium

Elements and electron shells one The atomic number of an element also tells us the number of electrons that an element has. These electrons are arranged in s_______ or orbits around the positive nucleus. These shells are also sometimes called e_______ levels. Electrons start filling the inner shell first. The inner shell contains two electrons. The next two shells each contain eight electrons. The fourth shell can contain up to eighteen electrons. Look at the first six elements: Hydrogen, Helium, Lithium, Beryllium, Boron and Carbon. How do the number of electrons found in the element’s outer shell relate to their position in the period table ? Elements and electron shells one Science Interactive LTD Copyright 2005 Word bank: shells energy Elements one to six Carbon Boron Beryllium Lithium Helium Hydrogen 3P + 4N 3E - 6P + 6N 6E - H 1 1 He 2 4 Li 3 7 Be 4 9 B 5 11 C 6 12 5P + 6N 5E - 4P + 5N 4E - 2P + 2E - 2N 1P + 1E -

Elements and electron shells two As the atomic number of an element increases, so do the number of electrons. When each electron shell is f_______ a new one begins to fill with electrons. It is the electron arrangement of an element that determines its c__________ properties. During chemical reactions, elements either gain, lose or share their electrons. Find out the difference in what happens to electrons during the formation of an ionic and covalent product ? Elements and electron shells two 20 28 31 32 40 39 19 Science Interactive LTD Copyright 2005 Word bank: filled chemical N 7 14 O 8 16 F 9 Ne 10 Na 11 23 Mg 12 24 Al 13 27 Si 14 P 15 S 16 Cl 17 35 Ar 18 K 19 Ca 20 40 Calcium Potassium Argon Chlorine Sulphur Phosphorus Silicon Aluminium Magnesium Sodium Neon Fluorine Oxygen Nitrogen

Compounds and relative formula mass one Once you understand the relative atomic mass of a______, you can also work out the relative mass of any molecule or compound. Using its formula, all you have to do is add up the masses of each type of atom present in the molecule. For example if the relative atomic mass of oxygen is 16 g then the relative formula mass for a molecule of oxygen is twice 16 g, therefore 32 g ( O 2 : 2 x 16 = 32 g ) Work out the relative formula mass for the following compounds SO 2 , CO 2 , C 2 H 6 & CO ? R.A.Ms: H = 1, C = 12, N= 14, O = 16, Ca = 20, Al = 27, S = 32 . Relative formula mass one + + Science Interactive LTD Copyright 2005 Word bank: atoms Methane Oxygen Water Nitrogen 2 N = 2 x 14 Total = 28 g 1 O = 1 x 16 2 H = 2 x 1 Total = 18 g 2 O = 2 x 16 Total = 32 g 1 C = 1 x 12 4 H = 4 x 1 Total = 16 g Relative formula mass (M r ) N 2 Nitrogen H 2 O Water Formula Diagram Compound CH 4 Methane O 2 Oxygen

Compounds and relative formula mass two Working with relative atomic and formula masses allows us, as scientists to solve problems involving qualities of raw m__________ and end products. Example: How much water in grams would be formed if I reacted 1000 g of hydrogen in excess oxygen . The equation tells us that 4 g of hydrogen reacts with 32 g of o_________ to produce 36 g of water. Therefore 1000 g of hydrogen would yield in excess oxygen 9000 g of water (250 x 36 = 9000) Work out the following relative formulae masses in the table below ? R.A.Ms: H = 1, C = 12, N= 14, O = 16, Ca = 20, Al = 27, S = 32 . Relative formula mass two Science Interactive LTD Copyright 2005 Word bank: materials oxygen __________ ? __________ ? Total = ___ ? __________ ? __________ ? Total = ___ ? __________ ? __________ ? Total = ___ ? 2 C = 2 x 12 2 H = 2 x 1 Total = 24 g Relative formula mass (M r ) CH 4 O Methanol H 2 O 2 Hydrogen peroxide Formula Diagram Compound C 2 H 2 Ethene NH 3 Ammonia

Equations and conservation of mass one When substances react, new products formed are shown by an equation. An equation tells you the substrates and their formulae and the resulting products and their formulae. During the r_________, bonds are broken and new ones are formed, however the number of atoms on both sides of the e__________ remain the same. Conservation of mass tell us that you can’t destroy or create atoms during a chemical reaction ! (R.A.Ms: H = 1, C = 12, O = 16) Combustion of methane with oxygen: Total (RHS) _____ ? Total (LHS) _______ ? Science Interactive LTD Copyright 2005 Word bank: reaction equation 4 H = 4 x 1 2 O = 2 x 16 Total = 36 g 1 C = 1 x 12 2 O = 2 x 16 Total = 44 g 4 O = 4 x 16 Total = 64 g 1 C = 1 x 12 4 H = 4 x 1 Total = 16 g Relative formula mass (Mr) 2H 2 O CO 2 2O 2 CH 4 Formula Water 2H 2 0 Carbon dioxide CO 2 + Diagram Equation Methane CH 4 + Oxygen 2O 2

Equations and conservation of mass two Conservation of mass tell us that you can’t destroy or create atoms during a chemical reaction ! This is true for all chemical reactions. An example is the formation of water. During this reaction, h_________ molecules (H 2 ) react with oxygen molecules (O 2 ) to form water molecules (H 2 0) At the beginning of the reaction, both the hydrogen and oxygen molecules are broken apart to form their a_______. These atoms then join one another, to form water molecules (H 2 O) Again the total number of atoms on either side remains the same ! (R.A.Ms: H = 1 & O = 16) Formation of water: Total (RHS) _______ ? Total (LHS) _______ ? H H H H O O H H O Science Interactive LTD Copyright 2005 Word bank: hydrogen atoms H H O 4 H = 4 x 1 2 O = 2 x 16 Total = 36 g 2 O = 2 x 16 Total = 32 g 4 H = 4 x 1 Total = 4 g Relative formula mass (Mr) 2H 2 O O 2 2H 2 Formula Diagram Equation Hydrogen + Oxygen Water

The mole one You know about relative atomic mass, but how was it worked out. For example, why is the RAM of carbon 12 and the RAM of oxygen 16 ? Well its all down to the mole . A mole in chemistry is a specific number of atoms, to be precise 6 x 10 23 atoms. It allows chemists to talk about the same number of p__________ for all the elements. For example 6.0 x 10 23 atoms of carbon weigh 12 g and 6.0 x 10 23 atoms of oxygen weighs exactly 16 g. The mole is the standard unit for particles. You can have a m______ of atoms, molecules, ions or even electrons, with whatever you have, its always 6 x 10 23 of them. The mole: 6.0 x 10 23 molecules 6.0 x 10 23 atoms 6.0 x 10 23 atoms 6.0 x 10 23 atoms Science Interactive LTD Copyright 2005 Word bank: particles mole H 1 1 C 6 12 1P + 1E - 6E - Hydrogen Carbon Oxygen O 2 O 8 16 6P + 6N 8N 8E - 8P + O 8 16 O 8 16 8N 8E - 8P + 8N 8E - 8P + 6.0 x 10 23 molecules Oxygen (Molecule) 6.0 x 10 23 atoms Oxygen (Atomic) Particles Diagram Compound 6.0 x 10 23 atoms Hydrogen 6.0 x 10 23 atoms Carbon

The mole two Working with relative atomic masses and the mole allows us to understand equations and know exactly how much substrates and p__________ are involved during a chemical reaction. Example : Haematite or iron ore is used to produce iron. In the blast furnace, iron ore is reduced by carbon monoxide to yield iron and carbon dioxide. How much iron will be produced from 100 kg of iron ore providing there is sufficient quantities of carbon monoxide ? Follow the solution ( R.A.Ms: C = 12 O = 16, Ca = 20, Fe = 56 ) Extracting iron: Science Interactive LTD Copyright 2005 Word bank: products Notes: The carbon in coke reacts with oxygen to form carbon monoxide a powerful reducing agent. Notes: The carbon monoxide gas displaces iron from its oxide producing carbon dioxide and molten iron which is then collected. Notes: Limestone reacts with silicon impurities to form slag which floats to the surface and is then removed. Formation of carbon monoxide 2C + O 2 2CO ( 1700 o C ) Reduction of iron oxide 3CO + Fe 2 O 3 2Fe + 3CO 2 ( 900 o C ) Impurity Formation (Slag) CaCO 3 + SiO 2 CASiO 3 ( 1200 o C ) Smelting process The equation tells us that 3 moles of carbon monoxide are required to reduce 1 mole of iron oxide producing 2 moles of iron metal and 3 moles of carbon dioxide . So how much iron in mass and moles will you obtain from 100 kg of iron ore ? Solution: M r of Fe 2 O 3 is 160 g (2 x 56 + 3 x 16) Every 160 g of iron oxide produces 112 g (2 x 56) of iron which gives a 70% yield (112/160). 100 kg of Fe 2 O 3 will therefore produce 70% or 70 kg of iron metal. 70 kg or 70,000 g of iron is equivalent to 1250 moles of iron (70,000/56). What would be the yield for 2500 kg of iron oxide be ? Calculation: Iron extraction

1: Define the following terms: Atom, Molecule, Compound, Element, Material & Particle 2: Complete the table. 3: a) Give three examples of each of the following; Elements, Single molecules and compounds b) Based on their physical properties answer the following.: Why is gold metal use for rings and necklaces. Why is iron used to build bridges and other structures like buildings. c) The chemical formula of carbon dioxide is CO 2 , of sugar C 6 H 12 O 6 what does this tell you about both molecules and the elements present. d) Work out the relative atomic mass (A r ) or relative formula mass (M r ) of the following: CaCO 3 , Al 2 O 3 , NaOH, H 2 , C 4 H 10 & C 12 H 24 , CuSO 4 , CO, H 2 0, Fe 2 O 3 , O 3 , O 2 , H 2 O 2 + SO 2 (RAM H = 1, C = 12, O = 16, Na = 23, Al = 27, S = 32 & Ca = 40) 4: Complete the table. Extension questions and homework 13 11 23 27 Science Interactive LTD Copyright 2005 92 143 92 U Uranium Al Al Aluminium 11 12 11 Na Na Sodium Electrons Neutrons Protons A r & RAM Symbol Element _______________________________? _____________________________? _________________________________? _____________________________? Pure element of only one type of atom E D C B A

5: Which one of the following reactions are correctly balanced? a) Fe 3 O 4 + 2H 2 3Fe + 2H 2 O b) H 2 0 H 2 + O 2 c) H 2 O 2 H 2 O + O 2 d) Mg(OH) 2 MgO + H 2 O e) 2Na + H 2 0 2NaOH + H 2 6: Balance these following equations: a) H 2 + O 2 H 2 O b) Al + O 2 Al 2 O 3 7: Choose from this word list to complete the sentences below: There are about _________ naturally occurring elements. From these elements ___________ of different substances can be made. 8: A pure substance was melted then allowed to cool. The temperature of the substance was measured every minute as it cooled down. The results are given. a) Plot a graph of temperature against time. b) What is the melting point of the substance. Internet: Go to google.co.uk and find out about the three forms of the element carbon; Diamond, Graphite and Buckminster fullerene. Cut and paste diagrams and write an a sentence about each type. Science Interactive LTD Copyright 2005 Twenty Ninety Thirty Tens Millions Hundreds 45 49 53 54 54 54 55 58 74 Temperature ( o C) 8 7 6 5 4 3 2 1 0 Time (min)