2. How do you know how many atoms and how many elements are in a symbol equation?
CO2
Tells you how many ELEMENTS there are (an easy way to do this is to count the capital letters)
The number tells you how many ATOMS of each of that element there is

3. Have a go… How many atoms and elements are in... H2O CaCO3 2MgO 2CaCl2
Mg(NO3) 2
Everything is multiplied by this number
Everything in the bracket is multiplied by this number

5. Filtration - separates fine, insoluble particles from a liquid
Fractional distillation – separates liquids with different boiling points
Condenser
Filter paper
Funnel
Conical flask
Filtration - separates fine, insoluble particles from a liquid
Chromatography – separates a mixture of chemicals / dyes
Evaporating dish
Bunsen burner
Tripod
Gauze
Fractional distillation – separates liquids with different boiling points
Evaporation / crystallisation – separates liquid from a dissolved substance

8. Order of discovery of sub atomic particles
Date
Scientist
Electron
1897
JJ Thomson
Proton
1919
Ernest Rutherford
Neutron
1932
James Chadwick

9. Rutherford Experiment: the set up
Geiger and Marsden counted the tiny green flashes in the microscope produced when alpha particles hit the screen.
Both Geiger and Marsden described this as one of the most difficult and boring experiments they’d ever had to do.
Moveable Microscope
Zinc sulphide screen
(glows when hit by alpha particles)
Shield
Source of alpha particles
Vacuum
(air pumped out)
Very thin gold foil

10. Geiger and Marsden placed the microscope as shown.
As expected, most of the alpha particles went straight through
A few alpha particles were scattered by angles less than 90º, also as expected.

11. Much to their surprise, a very small number of alpha particles (about 1 in 8000) bounced off the gold atoms!
Under protest, Geiger and Marsden placed the microscope behind the gold leaf.
They handed the results to Professor Rutherford who now had to explain what was going on.

12. Observations
Rutherford’s experiment finished with 3 observations. You need to explain what each observation tells us about the atom as we know it today
Most of the fast, highly charged alpha particles went whizzing straight through un-deflected.
Some of the alpha particles were deflected through a small angles
A very small number of alpha particles were deflected backwards!

13. SUGGESTS THAT MOST OF THE ATOM IS EMPTY SPACE!!
Conclusions
Most of the fast, highly charged alpha particles went whizzing straight through undeflected.
SUGGESTS THAT MOST OF THE ATOM IS EMPTY SPACE!!

14. Some of the alpha particles were deflected through a small angles!
Conclusions
Some of the alpha particles were deflected through a small angles!
SUGGESTS THAT THERE IS A CONCENTRATED POSITIVE MASS SOMEWHERE IN THE ATOM.

15. A very small number of alpha particles were deflected backwards!
Conclusions
A very small number of alpha particles were deflected backwards!
SUGGESTS THAT THE CONCENTRATED MASS IS MINISCULE COMPARED TO THE SIZE OF THE REST OF THE ATOM, BUT CONTAINS MOST OF THE MASS

16. What did Bohr do? (1913)
Realised that electrons should be attracted in to the nucleus
Used mathematical models to show that electrons occupy fixed energy levels (or shells) around the nucleus

18. Think about the location of:
Plum Pudding Model
Nuclear Model
Compare the differences between the plum pudding model and the nuclear model.
Think about the location of:
The mass
The negative charge
The positive charge
The density

21. The atom nucleus electron neutron
Draw a labelled diagram of the atom showing the nucleus and labelling protons, neutrons and electrons.
The overall charge on an atom is 0… what does this tell you about the number of protons and electrons?
nucleus
electron
Sub atomic particle
Relative charge
Relative Mass
Proton
Neutron
Electron
proton
neutron +1 1 1 -1
1/2000
(Very small)

23. How big is an atom?
Atoms are very small, having a radius of about 0.1 nm (1 x m)
The radius of a nucleus is less than 1/ of that of the atom
(about 1 x m)

24. What does this show you? 12 C 6 Atomic Mass number Carbon
(show the number of protons and neutrons in the nucleus)
(number of neutrons = top number – bottom number) 12 C 6
Carbon
Atomic number
(tells you the number of protons and the number of electrons)
How do we calculate mass and atomic numbers?

25. H H H Isotopes 1 2 1 3 1 Hydrogen Deuterium Tritium
Isotopes are atoms of the same element (same protons & electrons) with different numbers of neutrons. This makes them unstable.
Hydrogen
Deuterium
Tritium H 1 H 2 1 H 3 1

27. Isotopes and RAM
Many elements are a mixture of isotopes. The RAM given in the periodic table takes account of this.
To calculate the RAM of a mixture of isotopes, multiply the percentage of each isotope by its atomic mass and add them together.
For example, chlorine exists as two isotopes: chlorine-35 (75%) and chlorine-37 (25%).
= (0.75 x 35) + (0.25 x 37) =
= 35.5
RAM of chlorine = (75% x 35) + (25% x 37)

29. Electronic structure Chlorine Calcium Argon 2,8,7 2,8,8,2 2,8,8 xx xxCl xx xx x xx xx Ca xx xx x x x xx xx x x xx
2,8,7
2,8,8,2
2,8,8
Only a certain number of electrons can fit in each ‘shell’.
2 in the first shell
8 in the second shell
8 in the third shell

31. Group number = how many electrons in the outer shell
Alkali Metals
Nobel gases
Period number = how many shells the atom has
Halogens
Transition Metals

33. Development of the Periodic table
John Newlands (1865) –
Arranged elements in order of atomic weights (realised every 8th element had the same properties)
Didn’t leave gaps so only really worked up until calcium
Had lots more dissimilar elements in a column
Dmitri Mendeleev (1869) –
Left gaps for undiscovered elements
Changed the order of some elements so they fit with the properties
Elements with the predicted properties eventually discovered

35. What is an ION? An ION is a ‘charged’ particle.
Video
An ION is a ‘charged’ particle.
Atoms 'like' to have a full shell of electrons. They are more stable if they have a full electron shell. Atoms will lose or gain electrons in order to gain a full shell.
It has therefore either LOST or GAINED electrons.

36. Click on me!!
Remember that the proton number tells you how many protons or electrons the atom has.
Not any more!!!
Why not??

37. An ion is shown like this to show the electron shells
Or simply like this

38. The sodium ion + Sodium atom: Sodium ion: 11 protons = +11
11 electrons = -11
10 electrons = -10
Total charge = 0
Total charge = +1 Na + Na
one electron is lost
Electron arrangement: (partially full outer shell)
Electron arrangement: [2.8]+
(full outer shell)

39. The magnesium ion 2+ Magnesium atom: Magnesium ion: 12 protons = +12
12 electrons = -12
10 electrons = -10
Total charge = 0
Total charge = +2 Mg 2+ Mg
two electrons are lost
Electron arrangement: (partially full outer shell)
Electron arrangement: [2.8]2+
(full outer shell)

40. Negative ions
An atom that gains one or more electrons forms a negative ion. Non-metal atoms, such as chlorine, oxygen and nitrogen, form positive ions.
Negative ions have a small ‘-’ symbol and a number by them to indicate how many electrons they have gained to fill their outer shell. For example:
chloride ion = Cl- (not Cl1-)
chlorine atom =
oxygen atom = 2.6
oxide ion = O2-
nitrogen atom = 2.5
nitride ion = N3-
The name of the ion is slightly different to that of the atom – it ends ‘–ide’.

41. The fluoride ion - Fluorine atom: Fluoride ion: 9 protons = +9
9 electrons = -9
10 electrons = -10
Total charge = 0
Total charge = - 1 - F F
one electron is gained
Electron arrangement: 2.7 (partially full outer shell)
Electron arrangement: [2.8]-
(full outer shell)

42. two electrons are gained
The sulfide ion
Sulfur atom:
Sulfide ion:
16 protons = +16
16 protons = +16
16 electrons = -16
18 electrons = -18
Total charge = 0
Total charge = 2- S S
two electrons are gained
Electron arrangement: (partially full outer shell)
Electron arrangement: [2.8.8]2-
(full outer shell)

43. AN ATOM WITH A POSITIVE OR NEGATIVE CHARGE IS CALLED AN ION!!!!
Loss/gain of electrons
Charge of stable ion Li F Mg Cl O Al
Complete the table to show how each of the following atoms can become stable and what will be the charge on the ion?

45. Group 0

47. Group 1 (alkali) metals
More reactive
Higher melting point

48. Metals and oxygen – general equation
Potassium and sodium are metals that react vigorously with water even when a small amount of each metal is used.
metal
oxygen
metal oxide
Lithium + oxygen  Lithium oxide
Li O2  Li2O
Sodium + oxygen  ________ _______
Na O2  Na2O
Potassium + oxygen  ________ ______
K O2  K2O

49. Metals and chlorine – general equation
Potassium and sodium are metals that react vigorously with chlorine even when a small amount of each metal is used.
metal
chlorine
metal chloride
Lithium + chlorine  Lithium chloride
2Li Cl2  LiCl
Sodium + chlorine  ________ _______
2Na Cl2  NaCl
Potassium + chlorine  ________ ______
2K Cl2  KCl

50. Metals and water – general equation
Potassium and sodium are metals that react vigorously with water even when a small amount of each metal is used.
metal
water
metal hydroxide
hydrogen
Lithium + Water  Lithium Hydroxide + Hydrogen 2Li + 2H2O  2LiOH + H2 Sodium + Water  ________ _______ + Hydrogen 2Na + 2H2O  2NaOH + H2 Potassium + Water  ________ ______ + _______ 2K + 2H2O  2KOH + H2

53. Halogens
Less reactive

54. Halogen displacement
A more reactive halogen will displace and less reactive halogen from an aqueous solution of it’s salt
2KCl + I2
2KBr + I2
halogen
chlorine
bromine
iodine
salt (aq)
potassium chloride
potassium iodide
potassium bromide
2KCl + Br2
no reaction

55. Displacement Equations
Potassium Bromide and Chlorine:
2KBr + Cl2  2KCl + Br2
Potassium Iodide and Chlorine:
2KI + Cl2  2KCl + I2
Potassium Iodide and Bromine:
2KI + Br2  2KBr + I2

56. Electron shielding
Reasons why reactivity increases when you go down group 1, but decreases when you go down group 7.
Electrons are further away from the nucleus
Less attraction to the nucleus the further away the electrons are
Makes it easier to lose electrons if they are further away but harder to gain
Electrons between the nucleus repel other electrons

59. Physical properties of transition metals
They are good conductors of electricity and thermal energy
They are hard and strong
The have high densities
They have high melting points (with the exception of mercury which is a liquid at room temperature)
Transition metals have very high melting points compared with group 1 metals

60. Chemical properties of transition metals
Don’t react as strongly with oxygen, chlorine or water as the alkali metals do.
Most transition metals react very slowly with oxygen and water (e.g iron rusts very slowly over time)
Transition metals are much less reactive compared with group 1 metals

62. Compounds of transition elements
Transition elements form coloured compounds:
Copper (II) sulfate is blue
Nickel (II) carbonate pale green
Chromium (III) oxide is dark green
Manganese(II) chloride is pale pink
Transition metals can usually form more than one ion