Must collide with correct orientation for that reaction
Must collide with specific energy (EA)
What is activation energy?
Energy required to initiate a successful chemical reaction. In a reaction there often needs to be transition states that contain a level of enthalpy greater than both the products and reactants. These transition states occur as old bonds are broken and new bonds are formed. The materials at this point are referred to as an activated complex.
Increasing reaction rate:
Catalysts- create activation complex with a lower required EA, correctly orientate molecules.
Increase temperature- Increase # collisions, increase # collisions with sufficient energy
Increase concentration- More reacting particles
Increase pressure- Brings particles closer together->more likely to collide
Increase surface area- Reduce particle size, more particles exposed, more possible collisions.
Same formula, different structure
Properties of metallic substances:
Good conductors in both solid and liquid states
Hard, tough and dense
High melting and boiling points
Positive metal ions surrounded by a sea of delocalised electrons
Properties of ionic compounds
High melting and boiling points-strong electrostatic attraction between oppositely charged ions in 3d lattice
Made of hard crystals
Brittle-strong electrostatic attraction between oppositely charged ions in 3d lattice
Non-conductors in solid state- occupy fixed positions
Good conductors in liquid state- ions are able to move through liquid
Properties of covalent substances
Low melting and boiling points-weak attractive forces
Nonconductors as liquid and solid, sometimes aqueous- neutral particles and localised electrons
Organised in neutral lattice structure
Properties of covalent network substances:
Very high melting and boiling points- strong bonds in rigid lattice.
Non-conductors in solid and liquid states-localised and no electrons