Download - Atomic structure
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
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 Beryllium
Protons
Neutrons
Electrons
Beryllium has four electrons, four protons and five 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 Sodium
Protons
Neutrons
Electrons
Sodium has eleven electrons, eleven protons and twelve neutrons.
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
Na Mg
Al Si P S Cl Ar
K Ca Fe Ni Cu
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
Na Mg
Al Si P S Cl Ar
K Ca Fe Ni Cu
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
Na Mg
Al Si P S Cl Ar
K Ca Fe Ni Cu
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
Na Mg
Al Si P S Cl Ar
K Ca Fe Ni Cu
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
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 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 points
3) They exist as single atoms rather then diatomic molecules
4) 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 HalogensSome facts…
1) Reactivity DECREASES as you go down the group
Decre asing
react ivity
(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
HydrogenH
1 electron 0 electron 0 electron 0 electron
HeliumHe
2 electron 0 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
LithiumLi
2 electron 1 electron 0 electron 0 electron
BerylliumBe
2 electron 2 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
BoronB
2 electron 3 electron 0 electron 0 electron
CarbonC
2 electron 4 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
NitrogenN
2 electron 5 electron 0 electron 0 electron
OxygenO
2 electron 6 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
FluorineF
2 electron 7 electron 0 electron 0 electron
NeonNe
2 electron 8 electron 0 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
SodiumNa
2 electron 8 electron 1 electron 0 electron
MagnesiumMg
2 electron 8 electron 2 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
AluminiumAl
2 electron 8 electron 3 electron 0 electron
SiliconSi
2 electron 8 electron 4 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
PhosphorusP
2 electron 8 electron 5 electron 0 electron
SulphurS
2 electron 8 electron 6 electron 0 electron
How the shells fill with electrons
Element Shell 1 Shell 2 Shell 3 Shell 4
ChlorineCl
2 electron 8 electron 7 electron 0 electron
ArgonAr
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
CalciumCa
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.
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
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
HalogensNameFluorine
ColourPale Yellow
StateGas
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.