C4

All the important facts about C4 for the first exam... LEARN

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Atoms

Atoms are the building blocks of everything. They are tiny.

The nucleus:

  • Is the middle of the atom, containing protons and neutrons.
  • It has a positive charge because of the protons
  • Almost the whole mass is concentrated but its tiny compared to rest of atom.

The electrons:

  • Move around the nucleus
  • They are negatively charged
  • They are tiny with virtually no mass but cover a huge space
  • They are arranged in shells around the nucleus
  • The shells explain the whole of chemistry

Every element has a different number of protons.

THE NUMBER OF PROTONS= THE NUMBER OF ELECTRONS

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Balancing Equasions

Atoms are never lost nor made in chemical reactions. The number on each side always has to be ballanced.

Na+H2O ->NaOH+H2

But this doesn not ballance.... so experiment with the numbers until all the amounts are equal on each side as in relation to how the exuasion started.

2Na+2H2O+H2

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Line Spectrums

Some elements emit distinctive colours when heated:

Lithium produces a red flame.

Sodium produces a yellowy/ orange flame

Potassium produces a lilac flame

Colours seen in fireworks are due to the colours in different elements. When heated electrons release energy as light- Wavelengths can be recorded in a line spectrum.

A productive technique to produce line spectrums is called spectroscopy.

Line spectrums have identified new elements e.g.

Caesium and rubidium and hellium was discovered in the line spectrum from the sun.

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Periodic table

The periodic table puts elements with simular properties together.

It is laid out in order of increasing proton number.

Metals are found to the left

Non-metals are found to the right.

Vertical collums are called groups

Group one elements react more vigurously as you go down

Group seven elements react less vigurously as you go down.

The small number at the top is the relative atomic mass number The number at the botttomis the proton number.

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Electron Shells

The first shell can take 2 electrons

The second and thrid shells occupy up to 8 electrons

Electrons always want full shells; they look for other atoms to react with to get that they need. Its electron arrangement ditermines its chemical properties.

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Group 1) Alkaline Metals

As you go down they get more reactive, they have a lower melting and boiling point and a higher density.

  • Li. Lithium
  • Na. Sodium
  • K. Potassium
  • Rb. Rubidium
  • Cs. Caesium
  • Fr. Francium

Whe they react with cold water they give hydrogen gas. The reaction produces a Alkaline solution. They react very vigurously... Sodium hydroxide, lithium hydroxide..etc..

When they react with chlorine, they give salts... sodium chloride..

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Group7) Hallogens

Get less reactive as you go down. They have 7 outer electrons making them very reactive.

As you go down, they get less reactive, there is a higher melting and boiling point.

Hallogens are non-metals with coloured vapors:

  • Florine is a yellow gas at room temprature- very poisonus. 
  • Chlorine is a green, dense gas at room temprature - fairly poisonus.
  • Bromine is a red/ brown liduid ar room temprature, easily turns to gas
  • Iodine is a dark grey solid at room temprature and forms a purple vapor

These are all diatomic molecules and travel around in two's together. e.g. two chlorines travel together.

More reactive hallogens displace less reactive ones. e.g. Chlorine is more reactive then iodine. Chlorine reacts with potassium iodine solution to form potassium chloride and leaves iodine left sepperate from the solution.

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Ionic Bonding

This is the transformation of electrons.

They all want full shells therefore ones that only need to loose or gain one or two are VERY reactive. They go for atoms with opposite charge and stick to them like glue. Group 1 and 7 are nose reactive.

Electrons are negative therefore if an atom looses an electron it becomes positive. If it gains two it would become -2. This -2 will go to the opposite side of the other chemical bit, and will always be positive..

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