Chemistry Notes

On the right hand side of the periodic table.

They are called the noble gases because they are very unreactive.

The noble gases all have low boiling points. The boiling points then increase as you go down the group. This is because of the increasing atomic number that it causes the intermolecular forces between the atoms to increase, so more energy is needed to break them = the boiling points increase.

The densities increase as you go down the group. The particles in gases are spread far apart, so gases have low densities. 

Inert (don't react with much at all) because they are unstable (don't need to give up or gain electrons).

The group 1 elements are found on the left hand side of the periodic table. They are called the alkali metals because they form alkaline compounds. Recacitvity increases as you go down.

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All react vigorously with water to form a metal hydroxide and hydrogen:

metal + water → metal hydroxide + hydrogen

The metal hydroxides are strong alkalis.

Must be stored under oil to prevent the reacting to oxygen and water vapour in the air.

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The group 1 metals react vigorously with oxygen to form metal oxides. Lithium burns with a red flame, sodium with a yellow-orange flame, and potassium burns with a lilac flame.

A covalent bond is formed between non metal atoms, which combine together by sharing electrons. Covalent compounds have no free electrons and no ions so they don't conduct electricity.

Covalent compounds are usually gases or liquids with low melting points or boiling points and they don't conduct electricity

Low melting and boiling points

The covalent bonds binding the atoms together are very strong but there are only very weak forces holding the molecules to each other (the intermolecular forces). Therefore, only a low temperature is needed to separate the molecules when they are melted or boiled.

Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them.

What Happens:

• - Positively charged ions move to the negative electrode during electrolysis.They receive electrons and are reduced.
• - Negatively charged ions move to the positive electrode during electrolysis. They lose electrons and are oxidised.

The substance that is broken down is called the electrolyte.