Chemistry paper 1(the stuff i forget )

Properties of ionic compounds

• They have high melting or boiling points. This is because they have strong intermolecular forces of attraction which require lots of eneergy tp be broken.

• When solid the ions are held in place meaning they are unable to move therefoe cant conduct electricity.

  • When molten or dissolved in water the ions are free to move and carry electrical charge around the whole structure.

Properties of small molecular structures

• held together by covalent bonds

• Weak forces of attraction, this is because they have weak intermolecular forces of attraction so little energy is required to break the bonds giving them a low melting and boiling point

• They are gas or liquid at room temperature

• They dont conduct electricity because the ions arent charged and arent able to move around the whole strucutre and carry charge

Properties of Diamond

• Its a giant covalent structure

• Its made up of carbon atoms which form 4 covalent bonds making it hard

• Its got strong covalent bonds giivng it a high melting point

• Doesnt conduct electricity due to having no free electrons

What happens during electrolysis ?

An electric current is passed through a electroylte. This causes the ions to move to the electrodes where they form pure elements

What is a electrolyte?

A liquid or solution that contains ions, therfore can conduct electricity

what happens at the cathode

the negative electrode where ions lose elctrons

what happens at the anode

the positive electrode where they gain electrons

draw the electrolysis diagram

A visual representation showing the components of electrolysis, including the cathode, anode, electrolyte, and the flow of current.

describe electrolysis in molten ionic compounds

In solids electrolysis cant happen because the ions are in fixed shapes and therefore cant move. Howveer in molten ionic compounds can be electrolysed because the ions can move freely and conduct electricity. Positive metal ions move to the cathode and are reduced whereas negative non metal ions are oxidised and move to the anode

describe electrolysis in aqueous solutions

• electrolysis is used if a metal is more reactive than carbon

  1. Alluminium is extracted from alluminium oxide by electrolysis

  2. the alluminium substance is mixed with a substance called cryollite which lowers the melting point

  3. the mixture is then heated until it is molten

     4. the resulting molten mixture undergoes electrolysis

what is required for solid ionic compounds to undergo electrolysis when dissolved in water?

• it requires less energy to dissolve ionic compounds in water than to melt them

• However in the electrolysis of solutions the pure elements are not always produced because the water can also undergo ionisation → H20 > H+ + OH-