1. 25/08/2015 OCR Additional Science The Periodic Table

2. 25/08/2015Elements If a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron: These atoms are ALL iron – there’s nothing else in here

3. 25/08/2015Compounds Compounds are formed when two or more elements are chemically combined. Some examples: Glucose Methane Sodium chloride (salt)

4. 25/08/2015 Some simple compounds… Methane, CH 4 Water, H 2 O Carbon dioxide, CO 2 Ethyne, C 2 H 2 Sulphuric acid, H 2 SO 4 Key Hydrogen Oxygen Carbon Sulphur

5. 25/08/2015 Chemical formulae The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example… NaCl = sodium chloride (NaCl) KI = potassium iodide (KI) KN OOO = potassium nitrate (KNO 3 )

6. 25/08/2015 Chemical formulae Try drawing these: 1)Water H 2 O 2)Carbon dioxide CO 2 3)Calcium sulphate CaSO 4 4)Magnesium hydroxide Mg(OH) 2

7. 25/08/2015 Naming compounds Rule 1– If two identical elements combine then the name doesn’t change This happens with the following elements: 1)H 2 2)N 2 3)O 2 4)F 2 5)Cl 2 6)Br 2 These elements always go around in pairs (diatomic molecules). For example, hydrogen looks like this:

8. 25/08/2015 Naming compounds Rule 2 – When two elements join and one is a halogen, oxygen or sulphur the name ends with ____ide e.g. Magnesium + oxygen magnesium oxide 1)Sodium + chlorine 2)Magnesium + fluorine 3)Lithium + iodine 4)Chlorine + copper 5)Oxygen + iron 6)KBr 7)LiCl 8)CaO 9)MgS 10)KF

9. 25/08/2015 Naming compounds Rule 3 – When three or more elements combine and two of them are hydrogen and oxygen the name ends with hydroxide e.g. Sodium + hydrogen + oxygen Sodium hydroxide 1)Potassium + hydrogen + oxygen 2)Lithium + hydrogen + oxygen 3)Calcium + hydrogen + oxygen 4)Mg(OH) 2

10. 25/08/2015 Naming compounds Rule 4 – When three or more elements combine and one of them is oxygen the ending is _____ate e.g. Copper + sulphur + oxygenCopper sulphate 1)Calcium + carbon + oxygen 2)Potassium + carbon + oxygen 3)Calcium + sulphur + oxygen 4)Magnesium + chlorine + oxygen 5)Calcium + oxygen + nitrogen 6)AgNO 3 7)H 2 SO 4 8)K 2 CO 3

11. 25/08/2015 Simple formulae to learn “Covalent” formulae“Ionic” formulae H 2 O CO 2 NH 3 H 2 O 2 N 2 SO 2 Water Carbon dioxide Ammonia Hydrogen Oxygen Nitrogen Sulphur dioxide NaCl CaCl 2 MgO HCl H 2 SO 4 HNO 3 NaOH Ca(OH) 2 CaCO 3 Al 2 O 3 Fe 2 O 3 Sodium chloride Calcium chloride Magnesium oxide Hydrochloric acid Sulphuric acid Nitric acid Sodium hydroxide Calcium hydroxide Calcium carbonate Aluminium oxide Iron oxide

12. 25/08/2015 Balancing equations Consider the following reaction: Na O HH HH O H Sodium + water sodium hydroxide + hydrogen + + This equation doesn’t balance – there are 2 hydrogen atoms on the left hand side (the “reactants” and 3 on the right hand side (the “products”)

13. 25/08/2015 Balancing equations We need to balance the equation: Na O HH HH O H Sodium + water sodium hydroxide + hydrogen + + Na O HH O H Now the equation is balanced, and we can write it as: 2Na (s) + 2H 2 O (l) 2NaOH (aq) + H 2(g)

14. 25/08/2015 Some examples Mg + O 2 Zn + HCl Fe + Cl 2 NaOH + HCl CH 4 + O 2 Ca + H 2 O NaOH + H 2 SO 4 CH 3 OH + O 2 MgO ZnCl 2 + H 2 FeCl 3 NaCl + H 2 O CO 2 + H 2 O Ca(OH) 2 + H 2 Na 2 SO 4 + H 2 O CO 2 + H 2 O 2 2 2 3 2 2 2 2 2 2 2 2 4

15. 25/08/2015 The structure of the atom ELECTRON – negative, mass nearly nothing PROTON – positive, same mass as neutron (“1”) NEUTRON – neutral, same mass as proton (“1”) The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: Dalton

16. 25/08/2015 Mass and atomic number ParticleRelative MassRelative Charge Proton1+1 Neutron10 ElectronVery small MASS NUMBER = number of protons + number of neutrons SYMBOL PROTON NUMBER = number of protons (obviously)

17. 25/08/2015 Mass and atomic number How many protons, neutrons and electrons?

18. 25/08/2015Isotopes An isotope is an atom with a different number of neutrons: Each isotope has 8 protons – if it didn’t then it just wouldn’t be oxygen any more. Notice that the mass number is different. How many neutrons does each isotope have?

19. 25/08/2015 Electron structure Consider an atom of Potassium: Potassium has 19 electrons. These electrons occupy specific energy levels “shells”… Nucleus The inner shell has __ electrons The next shell has __ electrons The next shell has the remaining __ electron Electron structure = 2,8,8,1

20. 25/08/2015Bonding Hi. My name’s Johnny Chlorine. I’m in Group 7, so I have 7 electrons in my outer shell I’d quite like to have a full outer shell. To do this I need to GAIN an electron. Who can help me? Cl

21. 25/08/2015Bonding Here comes my friend, Sophie Sodium Hey Johnny. I’m in Group 1 so I have one electron in my outer shell. I don’t like having just one electron so I’m quite happy to get rid of it. Do you want it? Cl Now we’ve both got full outer shells and we’ve both gained a charge. We’ve formed an IONIC bond. Na Okay Cl Na + -

22. 25/08/2015Ions An ion is formed when an atom gains or loses electrons and becomes charged: If we “take away” the electron we’re left with just a positive charge: This is called an ion (in this case, a positive hydrogen ion) + - + The electron is negatively charged The proton is positively charged +

23. 25/08/2015 Ionic bonding Na + This is where a metal bonds with a non-metal (usually). Instead of sharing the electrons one of the atoms “_____” one or more electrons to the other. For example, consider sodium and chlorine: Sodium has 1 electron on its outer shell and chlorine has 7, so if sodium gives its electron to chlorine they both have a ___ outer shell and are ______. A _______ charged sodium ion (cation) A _________ charged chloride ion (anion) As opposed to covalent bonds, ionic bonds form strong forces of attraction between different ions due to their opposite ______, causing GIANT IONIC STRUCTURES to form (e.g sodium chloride) with ______ melting and boiling points: Cl -

24. 25/08/2015 Some examples of ionic bonding Mg Magnesium chloride: MgCl 2 Cl + Mg 2+ Cl - - Calcium oxide: CaO O Ca + 2+ O 2-

25. 25/08/2015 Balancing ions Determine the formula of the following compounds: 1)Sodium chloride 2)Magnesium oxide 3)Magnesium chloride 4)Ammonium chloride 5)Sodium sulphate 6)Sodium oxide Some common ions: Sodium – Na + Potassium – K + Magnesium – Mg 2+ Ammonium – NH 4 + Chloride – Cl - Bromide – Br - Oxide – O 2- Sulphate – SO 4 2-

26. 25/08/2015 Periodic Table Introduction

27. 25/08/2015 Mendeleev Periodic table The periodic table arranges all the elements in groups according to their properties. Horizontal rows are called PERIODS Vertical columns are called GROUPS

28. 25/08/2015 HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 1: Elements in the same group have the same number of electrons in the outer shell (this corresponds to their group number) E.g. all group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shell These elements have __ electrons in their outer shells

29. 25/08/2015 HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 2: As you move down through the periods an extra electron shell is added: E.g. Lithium has 3 electron in the configuration 2,1 Potassium has 19 electrons in the configuration __,__,__,__ Sodium has 11 electrons in the configuration 2,8,1

30. 25/08/2015 HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 3: Most of the elements are metals: These elements are metals This line divides metals from non- metals These elements are non-metals

31. 25/08/2015 HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY. E.g. consider the group 1 metals. They all: 1)Are soft 2)Can be easily cut with a knife 3)React with water

32. 25/08/2015 Bonding Revision Hi. My name’s Johnny Chlorine. I’m in Group 7, so I have 7 electrons in my outer shell I’d quite like to have a full outer shell. To do this I need to GAIN an electron. Who can help me? Cl

33. 25/08/2015 Ionic Bonding Revision Here comes my friend again, Sophie Sodium Hey Johnny. I’m in Group 1 so I have one electron in my outer shell. Unlike Harry, this electron is far away from the nucleus so I’m quite happy to get rid of it. Do you want it? Cl Now we’ve both got full outer shells and we’ve both gained a charge. We’ve formed an IONIC bond. Na Okay Cl Na + -

34. 25/08/2015 Covalent Bonding Here comes another one of my friends, Harry Hydrogen Hey Johnny. I’ve only got one electron but it’s really close to my nucleus so I don’t want to lose it. Fancy sharing? Cl H H Now we’re both really stable. We’ve formed a covalent bond.

35. 25/08/2015 Covalent bonding Consider an atom of hydrogen: Notice that hydrogen has just __ electron in its outer shell. A full (inner) shell would have __ electrons, so two hydrogen atoms get together and “_____” their electrons: Now they both have a ____ outer shell and are more _____. The formula for this molecule is H 2. When two or more atoms bond by sharing electrons we call it ____________ BONDING. This type of bonding normally occurs between _______ atoms. It causes the atoms in a molecule to be held together very strongly but there are ____ forces between individual molecules. This is why covalently-bonded molecules have low melting and boiling points (i.e. they are usually ____ or ______). Words – gas, covalent, non-metal, 1, 2, liquid, share, full, weak, stable

36. 25/08/2015 Dot and Cross Diagrams H O H Water, H 2 O:

37. 25/08/2015 Dot and Cross Diagrams Oxygen, O 2 : O O

38. 25/08/2015 Dot and cross diagrams Water, H 2 O: Oxygen, O 2 : OH HO O H H O O O Step 1: Draw the atoms with their outer shell: Step 2: Put the atoms together and check they all have a full outer shell:

39. 25/08/2015 Dot and cross diagrams Nitrogen, N 2 : Carbon dioxide, CO 2 : Ammonia NH 3 : Methane CH 4 : H H N H H H H H C N N O O C

40. 25/08/2015 Other ways of drawing covalent bonds Consider ammonia (NH 3 ): H H N H H H N H H H N H

41. 25/08/2015 Group 1 – The alkali metals Li Na K Rb Cs Fr

42. 25/08/2015 Group 1 – The alkali metals 1) These metals all have ___ electron in their outer shell. Some facts… 2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily. 3) They all react with water to form an alkali (hence their name) and __________, e.g: Words – down, one, shell, hydrogen, nucleus, decreases Potassium + water potassium hydroxide + hydrogen 2K (s) + 2H 2 O (l) 2KOH (aq) + H 2(g) 2) Density increases as you go down the group, while melting point ________

43. 25/08/2015 Trends in Group 1 Consider a sodium atom: Take away one of the electrons (oxidation) + + Now consider a potassium atom: Sodium ion Potassium ion Take away one of the electrons (oxidation) Potassium loses its electron more easily because its further away – potassium is MORE REACTIVE

44. 25/08/2015 Flame tests Compounds containing lithium, sodium, potassium, calcium and barium can be recognised by burning the compound and observing the colours produced: Lithium Red Sodium Yellow Potassium Lilac

45. 25/08/2015 Group 0 – The Noble gases He Ne Ar Kr Xe Rn

46. 25/08/2015 Group 0 – The Noble gases Some facts… 1) All of the noble gases have a full outer shell, so they are very ______ 2) They all have _____ melting and boiling points 3) They exist as single atoms rather then _________ molecules 4)Helium is ________ then air and is used in balloons and airships (as well as for talking in a silly voice) 5)Argon is used in light bulbs (because it is so unreactive) and argon, krypton and ____ are used in fancy lights Words – neon, stable, low, diatomic, lighter

47. 25/08/2015 Group 7 – The halogens F Cl Br I At

48. 25/08/2015 Group 7 – The Halogens Some facts… 1) Reactivity DECREASES as you go down the group Decreasing reactivity (This is because the electrons are further away from the nucleus and so any extra electrons aren’t attracted as much). 2) They exist as diatomic molecules (so that they both have a full outer shell): Cl 3) Because of this fluorine and chlorine are liquid at room temperature and bromine is a gas

49. 25/08/2015 The halogens – some reactions 1) Halogen + metal: Na + Cl - Na Cl + 2) Halogen + non-metal: H Cl + H Halogen + metal ionic salt Halogen + non-metal covalent molecule

50. 25/08/2015Properties ElementMelting Point ( O C)Boiling Point ( O C)Density (g/cm 3 ) Flourine-220-1880.0016 Chlorine-101-340.003 Bromine-7593.12 Iodine1141844.95 Astatine302?337???

51. 25/08/2015 Trends in Group 7 Consider a flourine atom: Add an electron (reduction) - - Now consider a chlorine atom: Flouride ion Chloride ion Add an electron (reduction) Chlorine doesn’t gain an electron as easily as flourine so it is LESS REACTIVE

52. 25/08/2015Electrolysis ++++++++ -------- Positive electrode (anode) Cu 2+ Negative electrode (cathode) Cl - Solution containing copper ions (cations) and chloride ions (anions)

53. 25/08/2015Electrolysis Electrolysis is used to separate a metal from its compound. = chloride ion = copper ion When we electrolysed copper chloride the _____ chloride ions moved to the ______ electrode and the ______ copper ions moved to the ______ electrode – OPPOSITES ATTRACT!!!

54. 25/08/2015 Electrolysis equations We need to be able to write “half equations” to show what happens during electrolysis (e.g. for copper chloride): 2 2 2 At the negative electrode the positive ions GAIN electrons to become neutral copper ATOMS. The half equation is: Cu 2+ + e - Cu At the positive electrode the negative ions LOSE electrons to become neutral chlorine MOLECULES. The half equation is: Cl - - e - Cl 2

55. 25/08/2015 Electrolysis of sulfuric acid AnodeCathode Sufuric acid is an electrolyte – it contains cations (H + ) and anions (OH - ) Oxygen gas (O 2 )Hydrogen gas (H 2 ) 2 2 4 4 2 H + (aq) + e - H 2(g) Half equations: OH - (aq) - e - H 2 O (l) + O 2(g)

56. 25/08/2015 Testing for Hydrogen “POP”

57. 25/08/2015 Testing for Oxygen Oxygen will relight a glowing splint

58. 25/08/2015 Extracting Aluminium Aluminium has to be extracted from its ore (called ________) by electrolysis. This is because aluminium is very ___________. The ore is mixed with cryolite to lower its ________ ________. The ore is then melted so that the ions can ______. The positively charged aluminium ions gather at the ___________ electrode. Oxygen forms at the positive electrode and causes it to wear away, which means that they have to be __________ frequently. Words – melting point, replaced, negative, bauxite, reactive, move

59. 25/08/2015 Electrolysis of Aluminium Oxide Overall: At the cathode:At the anode: Al 3+ (l) + 3e - Al (l) 2O 2- (l) - 4e - O 2(g) Aluminium oxide aluminium + oxygen 2Al 2 O 3(l) 4Al (l) + 3O 2(g)

60. 25/08/2015 The Transition Metals 1) This section includes metals like gold, mercury, iron, copper Some facts… 2) They are all ______ and solid (except _________) 3) They are ____ reactive than the alkali metals Words – hard, coloured, mercury, less, catalyst, insoluble 4) They can form __________ compounds, usually _______ 5) They can be used as a ______ (a chemical that speeds up a reaction)

61. 25/08/2015 Thermal decomposition Thermal Decomposition is when a substance breaks down into a simpler substance through the action of heat. For example, consider copper carbonate: Limewater Copper carbonate (green) turns into copper oxide (black) Limewater goes cloudy due to carbon dioxide being made Copper carbonate copper oxide + carbon dioxide

62. 25/08/2015 Metal ions and precipitates Some metal ions form precipitates, i.e. an insoluble solid that is formed when sodium hydroxide is added to them. Consider calcium chloride: Ca 2+ (aq) + OH - Ca(OH) 2 (s) 2 Metal ionPrecipitate formedColour Calcium Ca 2+ Calcium hydroxide: Ca 2+ (aq) + OH - (aq) Ca(OH) 2 (s) White Aluminium Al 3+ Magnesium Mg 2+ Copper (II) Cu 2+ Iron (II) Fe 2+ Iron (III) Fe 3+

63. 25/08/2015Metals Metal atoms are very closely packed together in a regular arrangement. The atoms are held together by metallic bonds.

64. 25/08/2015 A closer look at metals + + + + +++ + + Metals are defined as elements that readily lose electrons to form positive ions. There are a number of ways of drawing them: + - + - + - + - + - + - + - + - +++ +++ ++ Delocalised electrons

65. 25/08/2015 Properties of metals Metals have very high melting points (which means that they are usually _____) whereas non-metals will melt at lower ___________ All metals conduct heat and __________ very well, whereas non-metals don’t (usually) Metals are strong and ______ but bendable. Non-metals are usually _____ or they will snap. Metals will _____ when freshly cut or scratched, whereas non-metals are usually dull. Metals have higher _______ than non-metals (i.e. they weigh more) Metals can be used to make ______ (a mixture of different metals) Words - alloys, electricity, solids, weak, densities, temperatures, tough, shine

66. 25/08/2015Superconductors At low temperatures metals can become superconductors. A superconductor has very little or no resistance to the flow of electricity. Current research is being done to see if this will happen at room temperature, as it is only possible at very low temperatures at the moment.