What are atoms like???

By Alex Hulbert

An atom is made up of a nucleus that is surrounded by electrons.

The nucleus of a atom is made up of protons and neutrons

ProtonNeutron

The atomic number for the atom above is 2, this is because it has two protons.The mass number is the total

number of protons and neutrons in an atom.

The relative mass of a proton is 1 and the relative mass of a neutron is also 1.What is an isotope???

There are some elements that have the same atomic number but different mass numbers, these are isotopes

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 neutrons. Making it neutral.Examples of isotopes:

Isotope

1H1

2H1

3H1

Electrons

1

1

1

Protons

1

1

1

Neutrons

0

1

2

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.

E.g. the atomic number of carbon (C) is 6 and nitrogen is 7

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.

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.

In the periodic table neon is written as

20N10 can you work out how many neutrons it has???

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

ElectrolysisBy 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 re-lights.•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 metalsMost 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 metalsMetals 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 BondingA 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 SuperconductorsWhen 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 metalsType 2: which are alloys

The Meissner effectWhen 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, super-fast electronic circuits and powerful electromagnets.

More on delocalised electrons

A metal conducts electricity because delocalised electrons within a structure can move easily.