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Atomic structure
Mrs Griffiths
Wellington School
Visit www.worldofteaching.comFor 100’s of free powerpoints
Atomic Structure
The structure of the atom
ELECTRON – negative,
mass nearly nothingPROTON –
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
The Atom
Nucleus Electron
Shell or Orbit
The Atom Hydrogen
Proton Electron
Hydrogen has one proton, one electron and NO neutrons
The Atom Helium
ElectronProton
Neutron
Helium has two electrons, two protons and two neutrons
Mass and atomic numberParticle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron 0 -1
MASS NUMBER = number of protons + number of neutrons
SYMBOL
PROTON NUMBER = number of protons (obviously)
The Atom Helium
ElectronProton
Neutron
Helium has two electrons, two protons and two neutrons
The Atom Lithium
Protons
Neutrons
Electrons
The Atom Beryllium
Protons
Neutrons
Electrons
Beryllium has four electrons, four protons and five neutrons.
The Atom Boron
Protons
Neutrons
Electrons
Boron has five electrons, five protons and six neutrons.
The Atom Carbon
Protons
Neutrons
Electrons
Carbon has six electrons, six protons and six neutrons.
The Atom Nitrogen
Protons
Neutrons
Electrons
Nitrogen has seven electrons, seven protons and seven neutrons.
The Atom Oxygen
Protons
Neutrons
Electrons
Oxygen has eight electrons, eight protons and eight neutrons.
The Atom Fluorine
Protons
Neutrons
Electrons
Fluorine has nine electrons, nine protons and ten neutrons.
The Atom Neon
Protons
Neutrons
Electrons
Neon has ten electrons, ten protons and ten neutrons.
The Atom Sodium
Protons
Neutrons
Electrons
Sodium has eleven electrons, eleven protons and twelve neutrons.
How many protons, neutrons and electrons?
Mendeleev
Periodic tableThe periodic table arranges all the elements in groups according to their properties.
Horizontal rows are called PERIODS
Vertical columns are called GROUPS
H He
Li Be B C N O F Ne
NaMg
Al Si P S Cl Ar
K Ca Fe NiCu
Zn Br Kr
Ag I Xe
PtAu
Hg
The Periodic TableFact 1: Elements in the same group have the same number of electrons in the outer
shell (this correspond 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
H He
Li Be B C N O F Ne
NaMg
Al Si P S Cl Ar
K Ca Fe NiCu
Zn Br Kr
Ag I Xe
PtAu
Hg
The Periodic TableFact 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
H He
Li Be B C N O F Ne
NaMg
Al Si P S Cl Ar
K Ca Fe NiCu
Zn Br Kr
Ag I Xe
PtAu
Hg
The Periodic TableFact 3: Most of the elements are metals:
These elements are metals
This line divides metals from non-metals
These elements are non-metals
H He
Li Be B C N O F Ne
NaMg
Al Si P S Cl Ar
K Ca Fe NiCu
Zn Br Kr
Ag I Xe
PtAu
Hg
The Periodic TableFact 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
Group 1 – The alkali metals
Li
Na
K
Rb
Cs
Fr
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
Potassium + water potassium hydroxide + hydrogen
2K(s) + 2H2O(l) 2KOH(aq) + H2(g)
Group 0 – The Noble gasesHe
Ne
Ar
Kr
Xe
Rn
Group 0 – The Noble gasesSome facts…
1) All of the noble gases have a full outer shell, so they are very _____________
2) They all have low melting and boiling points3) They exist as single atoms rather then diatomic molecules4) Helium is lighter 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 neon are used in fancy lights
Group 7 – The halogens
F
Cl
Br
I
At
Group 7 – The HalogensSome facts…
1) Reactivity DECREASES as you go down the group
Decre
asin
greactiv
ity
(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
The halogens – some reactions1) Halogen + metal:
Na
+
Cl
-
Na Cl+
2) Halogen + non-metal:
H Cl+ Cl H
Halogen + metal ionic salt
Halogen + non-metal covalent molecule
How shells fill
• The first electron shell can only hold a maximum of two electrons.
• The second electron shell can hold a maximum of eight electrons.
• The third electron shell can also hold a maximum of eight electrons.
• The fourth electron shell can also hold eight electrons.
Electron structureConsider an atom of Potassium:
Potassium has 19 electrons. These are arranged in shells…
Nucleus
The inner shell has __ electrons
The next shell has __ electrons
The next shell has __ electrons
The next shell has the remaining __ electron
Electron structure
= 2,8,8,1
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Hydrogen
H
1 electron 0 electron 0 electron 0 electron
Helium
He
2 electron 0 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Lithium
Li
2 electron 1 electron 0 electron 0 electron
Beryllium
Be
2 electron 2 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Boron
B
2 electron 3 electron 0 electron 0 electron
Carbon
C
2 electron 4 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Nitrogen
N
2 electron 5 electron 0 electron 0 electron
Oxygen
O
2 electron 6 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Fluorine
F
2 electron 7 electron 0 electron 0 electron
Neon
Ne
2 electron 8 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Sodium
Na
2 electron 8 electron 1 electron 0 electron
Magnesium
Mg
2 electron 8 electron 2 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Aluminium
Al
2 electron 8 electron 3 electron 0 electron
Silicon
Si
2 electron 8 electron 4 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Phosphorus
P
2 electron 8 electron 5 electron 0 electron
Sulphur
S
2 electron 8 electron 6 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Chlorine
Cl
2 electron 8 electron 7 electron 0 electron
Argon
Ar
2 electron 8 electron 8 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
Potassium 2 electron 8 electron 8 electron 1 electron
Calcium
Ca
2 electron 8 electron 8 electron 2 electron
The First Twenty Elements
• Hydrogen 1,0,0,0
• Helium 2,0,0,0
• Lithium 2,1,0,0
• Beryllium 2,2,0,0
• Boron 2,3,0,0
• Carbon 2,4,0,0
• Nitrogen 2,5,0,0
First 20 Elements continued
• Oxygen 2,6,0,0
• Fluorine 2,7,0,0
• Neon 2,8,0,0
• Sodium 2,8,1,0
• Magnesium 2,8,2,0
• Aluminium 2,8,3,0
• Silicon 2,8,4,0
First 20 Elements continued
• Phosphorus 2,8,5,0
• Sulphur 2,8,6,0
• Chlorine 2,8,7,0
• Argon 2,8,8,0
• Potassium 2,8,8,1
• Calcium 2,8,8,2
The Alkali metals
• Lithium, Sodium and Potassium have one electron in their outer shell and this is why they are found in group one of the periodic table.
The Nobel gases
• The Nobel gases have full outer shells and they are found in group 0 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.
The Halogens
• Fluorine, Chlorine, Bromine and Iodine are the Halogens and they all have seven electrons in their outer shell. This is why they are found in group 7 of the periodic table.
Displacement
• Fluorine can displace Chlorine, Bromine and Iodine.
F Cl Br I
Displacement
• Chlorine can displace Bromine and Iodine but it cannot displace Fluorine
Cl Br I F
Displacement
• Bromine can displace Iodine but it cannot displace Fluorine or Chlorine
Br I F Cl
Displacement
• Iodine cannot displace Iodine Fluorine, Chlorine or Bromine
I F Cl Br
Fluorine reacts with sodium chloride. Which equation is
correctly shows this reaction?
• F2 + 2Na 2NaF
• F + Na NaF
• 2F + 2Na 2NaF
Which will displace?
• 2NaF + Cl2 Yes or No
• 2NaBr + Cl2 Yes or No
• 2KI + I2 Yes or No
• 2LiCl + I2 Yes or No
• 2NaBr + I2 Yes or No
• 2NaBr + F2 Yes or No
• Cl2 + 2NaBr Yes or No
Four factors affecting Reaction Rate
Catalysts Temperature
Concentration Surface Area
Catalyst
• A catalyst speeds up or slows down a reaction but does not get used up by the reaction.
Temperature
• If we increase the temperature of a reaction by 100C the rate will double this means the reaction will be complete in half the time.
Concentration
• If we increase the concentration of a reactant the number of particles increase that in turn increases the chance of a collision and initiates a chemical reaction.
Surface area
• The larger the particle size the smaller the relative area the slower the reaction.
• The smaller the particle size the greater the relative surface area and the faster the reaction.
Group 1
• Lithium, sodium and potassium are all in group 1.
• They all have one electron in the outer shell.
• They are all metals.
• They react with group 7 to form metal halides.
Group 7
• Fluorine ,Chlorine, Bromine and Iodine.
• They all have 7 electrons in their outer shell.
• They are all coloured.
• They form metal halides with group 1 metals.
Group 0
• These are the noble gases.
• They have complete electron shells.
• The electron shells are full.
• They are unreactive.
• They are inert.
• They do not react.
• They include, Helium, Neon, Argon, Krypton, Xenon and Radon
HalogensName
Fluorine
Colour
Pale Yellow
State
Gas
M.P.
-220
B.P.
-188
Chlorine Green Gas -101 -34
Bromine Brown Liquid -7 59
Iodine Slate grey
Solid 114 184
Reactions
• Sodium and Chlorine react to form
• Sodium Chloride.
• Iron and Chlorine react to form • Iron Chloride.
• 2Na + Cl2 2NaCl.
• Fe + Cl2 FeCl2.
Uses of the Halogens
• Fluorine is put into water supplies to kill harmful bacteria and to help keep teeth healthy.
• Chlorine is used in swimming pools to bacteria in the water.
• Bromine is used in pesticides. Silver bromide is used in photography.
• Iodine is an antiseptic on cuts and grazes.
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