What are atoms like???
By Alex Hulbert
An atom is made up of a nucleus
that is surrounded by electrons.
Neutron
Proton
The nucleus of a atom is made
up of protons and neutrons
The mass number is the total
number of protons and
neutrons in an atom.
What is an isotope???
There are some elements that
have the same atomic number
but different mass numbers,
these are isotopes
The atomic number for the atom
above is 2, this is because it has two
protons.
The relative mass of a
proton is 1 and the relative
mass of a neutron is also 1.
Why are atoms neutral???
An atom is neutral because it has and
equal number of electrons and protons,
which balances out the negative
charges.
Example: 14C6 has no charge so it
is an atom. It has 6 protons and a
mass of 14 (14-6) so must have 8
Examples of isotopes:
neutrons. Making it neutral.
Isotope
Electrons
Protons Neutrons
H1
1
1
0
H1
1
1
1
H1
1
1
2
1
2
3
Isotopes of an element,
in this case hydrogen
have different numbers
of neutrons in their
atoms
The arrangement of electrons in
atoms
Elements are arranged in
ascending atomic number in
the periodic table.
The same number of electrons
occupies the space around the
nucleus e.g. Oxygen has a atomic
number of 8. It has eight electrons
in the space around the nucleus.
In the periodic table
neon is written as
N10 can you work
20
out how many
neutrons it has???
E.g. the atomic
number of carbon
(C) is 6 and nitrogen
is 7
Electrons occupy ‘shells’. The
shell nearest the nucleus has
only 2 electrons but the next one
out has 8.
This is and
example of
anatomic
structure, this is
neon.
Electronic structure
Each element has an electron pattern
(electronic structure). The electronic
structure can be worked out using:
> The atomic number of the element
> The maximum number of the electrons in
each shell
The third shell takes up to eight electrons
before the forth shell starts to fill it takes up to
18 electrons.
Aluminum has an atomic number
13 so electrons start to occupy the
third shell, it is 2,8,3.
Calcium has the atomic number 20
so the electrons go into the fourth
shell and its electronic structure is
2,8,8,2
Electrolysis
By Alex Nour
• There are two electrode, the anode
which is positive and attracts
negative ions and the cathode
which attracts positive ions as it is
negative.
Electrolysis of dilute sulphuric
acid
• Hydrogen and Oxygen is made by
splitting up water but pure water doesn’t
conduct electricity and so sulphuric acid
is added.
• Hydrogen is produced at the cathode as
it is H+ and is discharged as H₂.
• Oxygen is OH- and so it goes to the
anode and is discharged as O₂.
• There is always twice as much hydrogen
as oxygen as water is H₂O.
Electrolysis of sodium
chloride
•The half equation of what happens
at the cathode is 2H+ + 2e- → H₂
•The half equation for the anode is
4OH- - 4e- → 2H₂O+ O₂
•To test for oxygen you hold a
glowing splint in oxygen and it relights.
•To test for hydrogen you hold a
lighted splint to it ad it makes a
squeaky pop.
Electrolysis of aluminium
oxide
• Aluminium is extracted from its
mineral bauxite using electrolysis.
• First the bauxite is melted so that its
ions are free to move.
• Electrodes are put through the
molten electrolyte.
• Aluminium is formed on the cathode
while oxygen is formed at the
anode.
• Aluminium oxide → aluminium +
oxygen
Electrolytic decomposition
• The process needs high electrical
input.
• Anodes are gradually worn away
Electrode Reactions
• Cathode:
• Al3+ +3e- →Al
• This is reduction as electrons are
gained.
• Anode:
• 2O₂- - 4e- → O₂
• Electrons are lost and so this is
oxidation.
High Energy Costs
• Aluminium is expensive as lots of
electricity is needed to get it.
• This is because aluminium has a
high melting point and so lots of
electricity is needed to reach it.
• Cryolite is added to lower the
melting point.
Transition elements are found in the middle of the periodic table.
They have metallic properties as they are metals:
• Conduct heat
• Are shiny
• Are sonorous
• Are malleable
• Are ductile
Coloured compounds are compounds that contain a transition element.
Copper compounds are blue.
Iron (11) compounds are pale green.
Iron (111) compounds are orange/brown.
- A transition element and its compound are often catalysts.
- Iron is used in the Haber process to make ammonia.
- Nickel is used in the manufacture of margarine.
Thermal decomposition is a reaction in which a substance is broken down into at
least 2 other substances by heat.
FeCO3 decomposes forming iron oxide and carbon dioxide.
CuCO3 decomposes forming copper oxide and carbon dioxide.
MnCO3 decomposes forming manganese oxide and carbon dioxide.
ZnCO3 decomposes forming zinc oxide and carbon dioxide.
The metal carbonates change colour during the reaction.
Hydroxide solution is used to identify the presence of transition metal ions in a
solution:
Cu2+ ions form a blue solid
Fe2+ ions form a grey/green solid
Fe3+ ions form an orange gelatinous solid.
Word equation for thermal decomposition:
Copper carbonate (arrow here) copper oxide + carbon dioxide
CuCO3 (arrow here) CuO + CO2
Properties of metals:
• Are lustrous
• Are hard
• Have a high density
• Have a high tensile strength
• Have a high boiling point and a high melting point
• Are good conductors of heat
Aluminium has a low density therefore is used where this
property is vital such as in the aircraft industry and in modern
cars.
Metals often have high melting points and boiling points
because a lot of energy is needed to overcome the strong
attraction between the delocalised electrons and the positive
metal ions.
At very low temperatures some metals become
superconductors which can be used to make super-fats
circuits and to levitate magnets.
This is because they conduct electricity with little or no
resistance. 2 types of superconductors are type 1 which
are metals and type 11 which are alloys.
A metal conducts electricity because delocalised
electrons within its structure can move easily.
Superconductors have some difficulties such as they
only work at low temperatures and they need to be
developed to work at 20 degrees C.
Properties Of metals
Most metals are lustrous, hard, malleable, ductile, have a high
density, a high tensile strength, have a high melting and
boiling point and are good conductors of heat and electricity.
A property can be either physical or chemical, for example:
• A physical property would be the high thermal conductivity of
copper.
• A chemical property would be the resistance to attack by
oxygen or acids shown by gold.
More on Properties Of metals
Metals such as Aluminium have a low density. This means they
are lightweight, making this property important for the
manufacturing of aircraft. This property is also used in modern
cars.
Metallic Bonding
A metallic bond is a strong electrostatic force of attraction
between close packed positive metal ions and a sea of
delocalised electrons
Metals have high boiling and melting points due to their strong
metallic bonds. This is because a lot of energy is needed to
break the strong forces of attraction between positive metal
ions and delocalised electrons.
Conductors and Superconductors
When a metal conducts electricity the electrons inside the metal
move. Copper, silver and gold conduct electricity very well but
don’t become superconductors.
At very low temperatures, metals become superconductors which
are used to make very fast circuits and to levitate magnets.
Superconductors conduct electricity with little or no resistance.
For example, the resistance of mercury suddenly drops at 268.8°C. This is called superconductivity. The temprature
where it drops is called the critical temperature.
There are two types of superconductor:
Type 1: which are metals
Type 2: which are alloys
The Meissner effect
When a substance becomes a superconductor it has no longer has
a magnetic fields. This is called the Meisser effect.
• If a small magnet is brought near the supersonductor, it is
repelled.
• If a small permanent magnet is brought near it, it levitates
Benefits of superconductors are loss-free power transition, superfast electronic circuits and powerful electromagnets.
More on delocalised electrons
A metal conducts electricity because delocalised electrons within
a structure can move easily.