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Igcse chemistry lesson 2

Igcse chemistry lesson 2. Section 1 Principles of Chemistry. States of matter Atoms Atomic structure Relative formula mass Chemical formulae and chemical equations Ionic compounds Covalent substances Metallic crystals Electrolysis. Lesson 2 Relative formula mass

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Igcse chemistry lesson 2

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  1. Igcse chemistry lesson 2

  2. Section 1 Principles of Chemistry • States of matter • Atoms • Atomic structure • Relative formula mass • Chemical formulae and chemical equations • Ionic compounds • Covalent substances • Metallic crystals • Electrolysis

  3. Lesson 2 • Relative formula mass • Chemical formulae and Chemical equations 1.15 calculate relative formula masses (Mr) from relative atomic masses (Ar) 1.16 understand the use of the term mole to represent the amount of substance 1.17 carry out mole calculations using relative atomic mass (Ar) and relative formula mass (Mr).

  4. What is RELATIVE ATOMIC MASS? By definition: “mass of a particular atom compared to the mass of an atom of hydrogen” Relative atomic mass is also the same as the mass number – it’s that simple!

  5. Relative Atomic Mass and Atomic Number Relative Atomic Mass = total number of protons and neutrons 23 Na 11 ATOMIC NUMBER = number of protons (also electrons) Relative atomic mass is always bigger than the atomic number

  6. Look up the Mass Numbers of the following elements:

  7. Look up the Mass Numbers of the following elements:

  8. When atoms join together to form a compound (eg. Magnesium oxide) we can calculate the RELATIVE FORMULA MASS:

  9. When atoms join together to form a compound (eg. Magnesium oxide) we can calculate the RELATIVE FORMULA MASS: Magnesium oxide MgO 24 + 16 = 40

  10. Chemical formulae MgO

  11. Chemical formulae MgO 1 Mg, 1 O

  12. Chemical formulae MgO 1 Mg, 1 O H2SO4

  13. Chemical formulae MgO 1 Mg, 1 O H2SO4 2H, 1 S, 4 O

  14. Chemical formulae MgO 1 Mg, 1 O H2SO4 2H, 1 S, 4 O Ca(OH)2

  15. Chemical formulae MgO 1 Mg, 1 O H2SO4 2H, 1 S, 4 O Ca(OH)2 1 Ca, 2 O, 2 H

  16. Chemical formulae MgO 1 Mg, 1 O H2SO4 2H, 1 S, 4 O Ca(OH)2 1 Ca, 2 O, 2 H 2Na2CO3

  17. Chemical formulae MgO 1 Mg, 1 O H2SO4 2H, 1 S, 4 O Ca(OH)2 1 Ca, 2 O, 2 H 2Na2CO3 4 Na, 2 C, 6 O

  18. When atoms join together to form a compound (eg. Magnesium oxide) we can calculate the RELATIVE FORMULA MASS: Magnesium oxide MgO 24 + 16 = 40

  19. Now calculate the Relative Formula Mass for the following compounds:

  20. Now calculate the Relative Formula Mass for the following compounds:

  21. Now calculate the Relative Formula Mass for the following compounds:

  22. Be aware! Relative Atomic Mass Ar

  23. Be aware! Relative Atomic Mass Ar Relative Formula Mass Mr

  24. The mole

  25. The mole You may think that the mole is a very blind animal that lives underground

  26. The mole The mole is also a measure widely used in chemistry

  27. The mole One mole is the relative formula mass (Mr) of a compound, or relative atomic mass (Ar) of an element, expressed in grams

  28. The mole For example, the Ar of carbon is 12.

  29. The mole For example, the Ar of carbon is 12. So the mass of one mole of carbon is 12g.

  30. The mole How simple is that? For example, the Ar of carbon is 12. So the mass of one mole of carbon is 12g.

  31. The mole What’s the mass of one mole of lead?

  32. The mole What’s the mass of one mole of lead? Ar of lead (Pb) = 207 So that mass of one mole of lead is 207g

  33. The mole Don’t panic! Let’s get a little more clever now and calculate the mass of moles from the relative formula mass (Mr)

  34. The mole For example, the Mr of sodium hydroxide: NaOH = 23 + 16 + 1 = 40

  35. The mole For example, the Mr of sodium hydroxide: NaOH = 23 + 16 + 1 = 40 So the mass of one mole of sodium hydroxide is 40g

  36. The mole What’s the mass of one mole of calcium carbonate?

  37. The mole What’s the mass of one mole of calcium carbonate? Mr of CaCO3 = 40 + 12 + 48 = 100

  38. The mole This isn’t rocket science! What’s the mass of one mole of calcium carbonate? Mr of CaCO3 = 40 + 12 + 48 = 100 So one mole of CaCO3 = 100g

  39. Important equation Steady as you go!

  40. Important equation Number of = mass used moles Mr Steady as you go!

  41. Important equation Number of = mass used moles Mr Steady as you go! Eg how many moles are there in 20g of sodium hydroxide?

  42. Important equation Number of = mass used moles Mr Steady as you go! Eg how many moles are there in 20g of sodium hydroxide? Number of = 20 moles 40 = 0.5

  43. Important equation Number of = mass used moles Mr Steady as you go! Eg how many moles are there in 20g of sodium hydroxide? Number of = 20 moles 40 = 0.5 We could even re-arrange the equation

  44. Number of = mass used moles Mr Mass used = number of x Mr moles

  45. Number of = mass used moles Mr Mass used = number of x Mr moles Eg. What’s the mass of 2 moles of calcium carbonate?

  46. Number of = mass used moles Mr Mass used = number of x Mr moles Eg. What’s the mass of 2 moles of calcium carbonate? Mass used = 2 x 100 = 200g

  47. The mole

  48. 1.18 write word equations and balanced chemical equations to represent the reactions studied in this specification 1.19 use the state symbols (s), (l), (g) and (aq) in chemical equations to represent solids, liquids, gases and aqueous solutions respectively 1.20 understand how the formulae of simple compounds can be obtained experimentally, including metal oxides, water and salts containing water of crystallisation 1.21 calculate empirical and molecular formulae from experimental data 1.22 calculate reacting masses using experimental data and chemical equations 1.23 carry out mole calculations using volumes and molar concentrations. • Lesson 2 • Relative formula mass • Chemical formulae and Chemical equations

  49. 1.18 write word equations and balanced chemical equations to represent the reactions studied in this specification 1.19 use the state symbols (s), (l), (g) and (aq) in chemical equations to represent solids, liquids, gases and aqueous solutions respectively 1.20 understand how the formulae of simple compounds can be obtained experimentally, including metal oxides, water and salts containing water of crystallisation 1.21 calculate empirical and molecular formulae from experimental data 1.22 calculate reacting masses using experimental data and chemical equations 1.23 carry out mole calculations using volumes and molar concentrations. • Lesson 2 • Relative formula mass • Chemical formulae and Chemical equations

  50. Using chemical symbols

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