1. OCR Additional Science
19/09/2018
OCR Additional Science
The Periodic Table
W Richards
The Weald School

2. These atoms are ALL iron – there’s nothing else in here
Elements
19/09/2018
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. Sodium chloride (salt)
Compounds
19/09/2018
Sodium chloride (salt)
Methane
Compounds are formed when two or more elements are chemically combined. Some examples:
Glucose

4. Some simple compounds…
19/09/2018
Methane, CH4
Carbon dioxide, CO2
Water, H2O
Key
Hydrogen
Oxygen
Carbon
Sulphur
Sulphuric acid, H2SO4
Ethyne, C2H2

5. Chemical formulae
19/09/2018
The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example… Na Cl
= sodium chloride (NaCl) K I
= potassium iodide (KI) O O
= potassium nitrate (KNO3) K N O

6. Chemical formulae Try drawing these: Water H2O Carbon dioxide CO2
19/09/2018
Try drawing these:
Water H2O
Carbon dioxide CO2
Calcium sulphate CaSO4
Magnesium hydroxide Mg(OH)2

7. Rule 1– If two identical elements combine then the name doesn’t change
Naming compounds
19/09/2018
Rule 1– If two identical elements combine then the name doesn’t change
This happens with the following elements: H2 N2 O2 F2
Cl2
Br2
These elements always go around in pairs (diatomic molecules). For example, hydrogen looks like this:

8. Naming compounds
19/09/2018
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
Sodium + chlorine
Magnesium + fluorine
Lithium + iodine
Chlorine + copper
Oxygen + iron
KBr
LiCl
CaO
MgS KF

9. e.g. Sodium + hydrogen + oxygen Sodium hydroxide
Naming compounds
19/09/2018
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
Potassium + hydrogen + oxygen
Lithium + hydrogen + oxygen
Calcium + hydrogen + oxygen
Mg(OH)2

10. e.g. Copper + sulphur + oxygen Copper sulphate
Naming compounds
19/09/2018
Rule 4 – When three or more elements combine and one of them is oxygen the ending is _____ate
e.g. Copper + sulphur + oxygen Copper sulphate
Calcium + carbon + oxygen
Potassium + carbon + oxygen
Calcium + sulphur + oxygen
Magnesium + chlorine + oxygen
Calcium + oxygen + nitrogen
AgNO3
H2SO4
K2CO3

11. Simple formulae to learn
19/09/2018
“Covalent” formulae
“Ionic” formulae
H2O
CO2
NH3 H2 O2 N2
SO2
Water
Carbon dioxide
Ammonia
Hydrogen
Oxygen
Nitrogen
Sulphur dioxide
NaCl
CaCl2
MgO
HCl
H2SO4
HNO3
NaOH
Ca(OH)2
CaCO3
Al2O3
Fe2O3
Sodium chloride
Calcium chloride
Magnesium oxide
Hydrochloric acid
Sulphuric acid
Nitric acid
Sodium hydroxide
Calcium hydroxide
Calcium carbonate
Aluminium oxide
Iron oxide

12. Sodium + water sodium hydroxide + hydrogen
Balancing equations
19/09/2018
Consider the following reaction:
Sodium + water sodium hydroxide + hydrogen Na O H O H Na + H +
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. Balancing equations We need to balance the equation:
19/09/2018
We need to balance the equation:
Sodium + water sodium hydroxide + hydrogen Na O H O H Na O H Na O H + H + Na
Now the equation is balanced, and we can write it as:
2Na(s) + 2H2O(l) NaOH(aq) + H2(g)

14. Some examples 2 2 3 2 3 Mg + O2 Zn + HCl Fe + Cl2 NaOH + HCl CH4 + O2
19/09/2018 2
Mg O2
Zn HCl
Fe Cl2
NaOH HCl
CH O2
Ca H2O
NaOH H2SO4
CH3OH O2
MgO
ZnCl H2
FeCl3
NaCl H2O
CO H2O
Ca(OH) H2
Na2SO H2O 2

15. The structure of the atom
19/09/2018
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
ELECTRON – negative, mass nearly nothing
PROTON – positive, same mass as neutron (“1”)
NEUTRON – neutral, same mass as proton (“1”)

16. Mass and atomic number 4 He 2
19/09/2018
Particle
Relative Mass
Relative Charge
Proton 1 +1
Neutron
Electron
Very small -1
MASS NUMBER = number of protons + number of neutrons He 2 4
SYMBOL
ATOMIC/PROTON NUMBER = number of protons (obviously)

17. How many protons, neutrons and electrons?
Mass and atomic number
19/09/2018
How many protons, neutrons and electrons? 1 11 16 H B O 1 5 8 23 35
238 Na Cl U 11 17 92

18. Isotopes
19/09/2018
An isotope is an atom with a different number of neutrons:
Notice that the mass number is different. How many neutrons does each isotope have? O 8 16 O 8 17 O 8 18
Each isotope has 8 protons – if it didn’t then it just wouldn’t be oxygen any more.

19. Electron structure 39 K 19 Consider an atom of Potassium:
19/09/2018
Consider an atom of Potassium:
Nucleus K 19 39
Potassium has 19 electrons. These electrons occupy specific energy levels “shells”…
The inner shell has __ electrons
The next shell has __ electrons
The next shell has the remaining __ electron
Electron structure
= 2,8,8,1

20. Bonding
19/09/2018 Cl
Hi. My name’s Johnny Chlorine. I’m in Group 7, so I have 7 electrons in my outer shell Cl
I’d quite like to have a full outer shell. To do this I need to GAIN an electron. Who can help me?

21. Here comes my friend, Sophie Sodium
Bonding
19/09/2018 Cl
Here comes my friend, Sophie Sodium Na
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?
Okay - + Cl Na
Now we’ve both got full outer shells and we’ve both gained a charge. We’ve formed an IONIC bond.

22. This is called an ion (in this case, a positive hydrogen ion)
Ions
19/09/2018
An ion is formed when an atom gains or loses electrons and becomes charged: + -
The electron is negatively charged
The proton is positively 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)

23. Ionic bonding Na Cl Na + Cl -
19/09/2018
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: Na Cl Na + Cl -

24. Some examples of ionic bonding
19/09/2018 Cl -
Magnesium chloride: Cl Mg 2+ Mg + Cl - Cl
MgCl2
Calcium oxide: O Ca + 2+ 2-
CaO

25. Balancing ions Some common ions:
19/09/2018
Some common ions:
Sodium – Na+
Potassium – K+
Magnesium – Mg2+
Ammonium – NH4+
Chloride – Cl-
Bromide – Br-
Oxide – O2-
Sulphate – SO42-
Determine the formula of the following compounds:
Sodium chloride
Magnesium oxide
Magnesium chloride
Ammonium chloride
Sodium sulphate
Sodium oxide

26. Periodic Table Introduction
19/09/2018
Periodic Table Introduction

27. Horizontal rows are called PERIODS
Periodic table
19/09/2018
Mendeleev
The periodic table arranges all the elements in groups according to their properties.
Vertical columns are called GROUPS
Horizontal rows are called PERIODS

28. The Periodic Table
19/09/2018
Fact 1: Elements in the same group have the same number of electrons in the outer shell (this corresponds to their group number) H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
These elements have __ electrons in their outer shells
These elements have __ electrons in their outer shell
E.g. all group 1 metals have __ electron in their outer shell

29. The Periodic Table
19/09/2018
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 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
Sodium has 11 electrons in the configuration 2,8,1
Potassium has 19 electrons in the configuration __,__,__,__

30. Fact 3: Most of the elements are metals:
The Periodic Table
19/09/2018
Fact 3: Most of the elements are metals:
These elements are metals H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
These elements are non-metals
This line divides metals from non-metals

31. The Periodic Table
19/09/2018
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. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
E.g. consider the group 1 metals. They all:
Are soft
Can be easily cut with a knife
React with water

32. Bonding Revision
19/09/2018 Cl
Hi. My name’s Johnny Chlorine. I’m in Group 7, so I have 7 electrons in my outer shell Cl
I’d quite like to have a full outer shell. To do this I need to GAIN an electron. Who can help me?

33. Ionic Bonding Revision
19/09/2018 Cl
Here comes my friend again, Sophie Sodium Na
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?
Okay - + Cl Na
Now we’ve both got full outer shells and we’ve both gained a charge. We’ve formed an IONIC bond.

34. Covalent Bonding
19/09/2018 Cl
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? H Cl H
Now we’re both really stable. We’ve formed a covalent bond.

35. Covalent bonding Consider an atom of hydrogen:
19/09/2018
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 H2.
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. Dot and Cross Diagrams
19/09/2018
Water, H2O: H H O

37. Dot and Cross Diagrams
19/09/2018
Oxygen, O2: O O

38. Dot and cross diagrams Water, H2O: H O O H H Oxygen, O2: O O O
19/09/2018
Water, H2O:
Step 1: Draw the atoms with their outer shell:
Step 2: Put the atoms together and check they all have a full outer shell: H O O H H
Oxygen, O2: O O O

39. Dot and cross diagrams Nitrogen, N2: Methane CH4: N C H Ammonia NH3:
19/09/2018
Nitrogen, N2:
Methane CH4: H C N
Ammonia NH3:
Carbon dioxide, CO2: H N O C

40. Other ways of drawing covalent bonds
19/09/2018
Consider ammonia (NH3): H N H N H N

41. Group 1 – The alkali metals
19/09/2018 Li Na K Rb Cs Fr

42. Group 1 – The alkali metals
19/09/2018
Some facts…
1) These metals all have ___ electron in their outer shell.
2) Density increases as you go down the group, while melting point ________
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:
Potassium + water potassium hydroxide + hydrogen
2K(s) H2O(l) KOH(aq) H2(g)
Words – down, one, shell, hydrogen, nucleus, decreases

43. Trends in Group 1 Consider a sodium atom: +
19/09/2018
Consider a sodium atom: +
Take away one of the electrons (oxidation)
Sodium ion
Now consider a potassium atom: +
Take away one of the electrons (oxidation)
Potassium ion
Potassium loses its electron more easily because its further away – potassium is MORE REACTIVE

44. Flame tests
19/09/2018
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. Group 0 – The Noble gases
19/09/2018 He Ne Ar Kr Xe Rn

46. Words – neon, stable, low, diatomic, lighter
Group 0 – The Noble gases
19/09/2018
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
Helium is ________ then air and is used in balloons and airships (as well as for talking in a silly voice)
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. Group 7 – The halogens
19/09/2018 F Cl Br I At

48. Group 7 – The Halogens Some facts… Decreasing reactivity
19/09/2018
Some facts…
Decreasing
reactivity
1) Reactivity DECREASES as you go down the group
(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 Cl
3) Because of this fluorine and chlorine are liquid at room temperature and bromine is a gas

49. The halogens – some reactions
19/09/2018
1) Halogen + metal: Na + Cl - Na Cl +
Halogen + metal ionic salt
2) Halogen + non-metal: Cl Cl H H +
Halogen + non-metal covalent molecule

50. Properties Element Melting Point (OC) Boiling Point (OC)
19/09/2018
Element
Melting Point (OC)
Boiling Point (OC)
Density (g/cm3)
Flourine
-220
-188
0.0016
Chlorine
-101
-34
0.003
Bromine -7 59
3.12
Iodine
114
184
4.95
Astatine
302?
337? ??

51. Trends in Group 7 Consider a flourine atom: -
19/09/2018
Consider a flourine atom: -
Add an electron (reduction)
Flouride ion
Now consider a chlorine atom: -
Add an electron (reduction)
Chloride ion
Chlorine doesn’t gain an electron as easily as flourine so it is LESS REACTIVE

52. Electrolysis ++++ ---- Positive electrode (anode)
19/09/2018
Positive electrode (anode)
Negative electrode (cathode)
++++
----
Cu2+
Cl-
Solution containing copper ions (cations) and chloride ions (anions)
Cu2+
Cl-
Cu2+
Cl-

53. Electrolysis
19/09/2018
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. Electrolysis equations
19/09/2018
We need to be able to write “half equations” to show what happens during electrolysis (e.g. for copper chloride):
At the negative electrode the positive ions GAIN electrons to become neutral copper ATOMS. The half equation is:
Cu e Cu 2
At the positive electrode the negative ions LOSE electrons to become neutral chlorine MOLECULES. The half equation is:
Cl e Cl2 2 2

55. Electrolysis of sulfuric acid
19/09/2018
Sufuric acid is an electrolyte – it contains cations (H+) and anions (OH-)
Oxygen gas (O2)
Hydrogen gas (H2)
Anode
Cathode
H+(aq) e H2(g)
Half equations:
OH-(aq) e H2O(l) + O2(g)

56. Testing for Hydrogen
19/09/2018
“POP”

57. Testing for Oxygen
19/09/2018
Oxygen will relight a glowing splint

58. Words – melting point, replaced, negative, bauxite, reactive, move
Extracting Aluminium
19/09/2018
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. Electrolysis of Aluminium Oxide
19/09/2018
Overall:
Aluminium oxide aluminium + oxygen
2Al2O3(l) Al(l) O2(g)
At the cathode:
At the anode:
Al3+(l) + 3e Al(l)
2O2-(l) - 4e O2(g)

60. Words – hard, coloured, mercury, less, catalyst, insoluble
The Transition Metals
19/09/2018
Some facts…
1) This section includes metals like gold, mercury, iron, copper
2) They are all ______ and solid (except _________)
3) They are ____ reactive than the alkali metals
4) They can form __________ compounds, usually _______
5) They can be used as a ______ (a chemical that speeds up a reaction)
Words – hard, coloured, mercury, less, catalyst, insoluble

61. Thermal decomposition
19/09/2018
Thermal Decomposition is when a substance breaks down into a simpler substance through the action of heat. For example, consider copper carbonate:
Copper carbonate (green) turns into copper oxide (black)
Limewater
Limewater goes cloudy due to carbon dioxide being made
Copper carbonate copper oxide + carbon dioxide

62. Metal ions and precipitates
19/09/2018
Some metal ions form precipitates, i.e. an insoluble solid that is formed when sodium hydroxide is added to them. Consider calcium chloride:
Ca2+(aq) OH Ca(OH)2 (s) 2
Metal ion
Precipitate formed
Colour
Calcium Ca2+
Calcium hydroxide: Ca2+(aq) + OH-(aq) Ca(OH)2 (s)
White
Aluminium Al3+
Magnesium Mg2+
Copper(II) Cu2+
Iron(II) Fe2+
Iron(III) Fe3+

63. Metals
19/09/2018
Metal atoms are very closely packed together in a regular arrangement. The atoms are held together by metallic bonds.

64. Delocalised electrons
A closer look at metals
19/09/2018 +
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. Properties of metals
19/09/2018
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. Superconductors
19/09/2018
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.