Chapter 4 Matter and Substances


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Chapter 4 Matter and Substances

  1. 1. Chapter 4 Matter and Substances
  2. 2. 4.1 Changes In Matter Kinetic Theory of Matter The theory states that: - Matter is made up of tiny and discrete particles - The particles are always moving in random motion - The moving energy is called the kinetic energy of particles - The kinetic energy of particles depends on the temperature of matter
  3. 3. States of Matter
  4. 4. Changes in state of matter Sublimation Sublimation
  5. 5. 4.2 Structure of atom Every substances is made up of atoms. 2. There are three types of subatomic particles: proton, electron and neutron. 1. (e, negatively charged) (p, positively charged) (n, neutral/ no charged)
  6. 6. 4.3 Proton number and Nucleon number Proton number is the number of proton in an atom.  Nucleon number is the total number of protons and neutrons in an atom.  The number of nucleon = neutrons number + proton number • Symbol of element. For example, Aluminium (Al) Proton number (always smaller number) Nucleon number 13 27 Al Name of element
  7. 7. How to determine the charges of particles Particles A Number of protons 6 Number of electrons 8 B C 10 11 9 11 a) Positively charged particles: B ( more proton number) b) Negatively charged particles: A (more electron number) c) Particle that has no charge (neutral): C (proton = electro
  8. 8. Isotopes Isotopes of certain elements contains the same number of protons but a different number of neutrons in their atoms.  For example, hydrogen 
  9. 9. 4.4 Periodic table •Elements are arranged according to their proton number (increases) •Divided into metals, non-metals and semimetals •Elements in the same group have same chemical properties
  10. 10. Importance of periodic table Helps us to determine the properties of elements.  Can be used to forecast the properties and uses of particular element. 
  11. 11. 4.5 Properties of Substances ATOMS MOLECULES IONS •Substances made up of atoms only. •The smallest particle. Substance made up of molecules only (two or more atoms). •Substance made up of ions only. •Contain charged particle •In solid (except mercury) •Conduct electricity •High boiling/melting point •In solid, liquid or gas •Cannot conduct electricity •Low boiling/melting point •In solid •Cannot conduct electricity except in molten or aqueous states •High boiling/melting point ALUMINIUM Oxygen gas Aluminiu m Water Sodium chloride (NaCl)
  12. 12. Physical properties of substance made up of atoms, molecules and ions Section A: Melting point. Type of substance Melting point Lead ATOM High Sulphur Lead/sulphur/ Lead(II)bromide Substance s MOLECULE Low Lead (II) Bromide ION High •High melting point = strong forces of attraction •Low melting point = weak forces of attraction
  13. 13. Section B: Electrical conductivity SUBSTANCE ELECTRICAL CONDUCTIVITY SOLID MOLTEN LEAD Can Can SULPHUR Cannot Cannot LEAD(II)BROMID Cannot E Can For ionic substance, lead(II)bromide: •Does not conduct electricity in solid becaus - ions cannot move freely •Conducts electricity in molten because - ions can move freely
  14. 14. 4.6 Properties of Metals and NonMetals A) Surface condition Metals: copper Shiny surface Dull Non-metals: carbon
  15. 15. B) Malleability •Non-metal: Brittle • the lump of carbon shatters •Metal :Malleable • iron wire changes shape
  16. 16. C) Tensile strength Nichrome/ nylon Nichrome (metal) needed more weights to break Nylon (non-metal) needed less weight to break Metals have higher tensile strength than non-metals
  17. 17. D) Electrical conductivity * Metals: the bulb lights up with copper rod * METALS conduct electricity * Non-metals: the bulb does not lights up with glass rod * NON-METALS do not conduct electricity
  18. 18. E) Heat conductivity Type of Example Time taken materials for the thumbtack to drop off/second s METALS Copper rod 96 NONMETALS Glass rod 130 •Metals: copper rod are good heat conductors •Non-metals: glass rod are poor heat conductors
  19. 19. 4.6 Properties of Metals and Non-Metals Comparison between metals and non-metals METALS Physical properties NON-METALS Shiny Surface Dull Ductile Ductility Non-ductile/ brittle Malleable Malleability Non-malleable High Low Good Melting and Boiling point Electrical conductivity Good Heat conductivity Poor High Tensile strenght Low Non-conductive except carbon
  20. 20. Uses of metals Iron is used in making cars Copper is used to make wires Silver is often used to make jewellery Aluminium is used to make power lines
  21. 21. Uses of non-metals Sulphur is used to make matchstick tips Diamonds are mostly used to make jewellery Sulphur is ingredient in making paint
  22. 22. 4.7 Purification of Substances 1. 2. Pure substances are substances that contain only one type of substance. - do not have any impurities - for example, * pure sugar only contains sugar molecules * pure water only contains water molecules Pure substances have fixed boiling and melting point. - for example, * pure water boils at 100°C
  23. 23. Effect of impurities on the boiling point of a pure liquid  • The presence of impurities in a pure substance can a) increase its boiling point b) decrease its freezing point For example, - when a salt is added to pure water, water will be boil at a temperature higher than 100°C
  24. 24. Title: Effect of impurities on the boiling point of a pure liquid (PEKA) Aim: To study the effect of impurities on the boiling point.  Hypothesis: The presence of salt increases the boiling point of a pure liquid  Variables: manipulated variable : responding variable : constant variable :  Materials: distilled water, table salt  Apparatus: 100cm³beaker, wire gauze, tripod stand, Bunsen burner, thermomater 
  25. 25.  Procedure: Salt Distilled water 1. Distilled water was filled into a beaker until it is half full. 2. The water was heated until its boils. The temperature was recorded. 3. Two spatulas of table salt were added into the distilled water and the mixture was heated again. 4. The boiling point of the mixture of water and table salt were recorded.
  26. 26.  Results : • Conclusion: Boiling point of distilled water (°C) Absent Present • Analysis: The presence of table salt 100
  27. 27. Methods of purification Purification is a process of removing impurities from a substance.  The methods are: a) Filtration: process of separating solid from liquid  Mixture of solid and liquid Filter paper Residue (solid) Filtrate (liquid)
  28. 28. b) Crystallisation : process of forming crystals from a liquid or gas - production of salt from sea water - production of pure solid copper(II)sulphate from its solution Substance in crystal form
  29. 29. c) Distillation: a process to obtain a pure liquid from a solution of liquid mixture. - production of distilled water - petroleum fractions (fractional distillation) Tap water flows to cool the vapour and condense it into liquid To make sure the condenser is fully filled with water Porcelin chips: To break up the air bubbles
  30. 30. Fractional distillation
  31. 31. 4.8 Uses of various substances Humans need various types of substances in daily life.  With scientific knowledge and technology, humans have used the properties of substances to make their lives better.  For example, pure metals which may not be suitable for a particular purpose because they are too heavy or rust easily. - they can be processed into more suitable substances. - pure iron steel (strong and does not rust) 