Atomic Structure

Atomic structure

Mrs Griffiths

Wellington School

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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

Na Mg Al Si P S Cl Ar

K Ca Fe Ni Cu Zn Br Kr

Ag I Xe

Pt Au 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



Ag I Xe

Pt Au 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



Ag I Xe

Pt Au 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



Ag I Xe

Pt Au 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




Lithium

Li


Beryllium

Be




Boron

B


Carbon

C




Nitrogen

N


Oxygen

O




Fluorine

F


Neon

Ne




Sodium

Na


Magnesium

Mg




Aluminium

Al


Silicon

Si




Phosphorus

P


Sulphur

S




Chlorine

Cl


Argon

Ar




Potassium 2 electron 8 electron 8 electron 1 electron

Calcium

Ca


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.

Atomic Structure

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