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KEY CONCEPTS IN CHEMISTRY (Chemical Equations (Need-to-know formulas…
KEY CONCEPTS IN CHEMISTRY
Chemical Equations
Word equations
eg. methane + oxygen -> carbon dioxide + water
Chemical equations
eg. magnesium + oxygen -> magnesium oxide
2Mg + O2 -> 2MgO
You balance the equation by putting numbers in front of the formula where needed
State symbols
Solid (s)
Liquid (l)
Gas (g)
Aqueous (aq)
Need-to-know formulas
Water - H20
Carbon Dioxide - CO2
Chlorine - Cl2
Ammonia - NH3
Hydrogen - H2
Oxygen - O2
Need-to-know ions
Ammonium - NH4 (+)
Nitrate - NO3 (-)
Sulfate - SO4 (2-)
Hydroxide - OH(-)
Carbonate - CO3 (2-)
Hazards and Risk
Many chemistry experiments have risksk associated with them. These can include:
Risk associated with equipment
breaking glass
risk of fire from a bunsen burner
One way to reduce this risk is to carry out a risk assesment to identify the risks and how to prevent them
History of the atom
At the start of the 19th century, John Dalton described atoms as solid spheres and said that different spheres were made up of different elements
In 1897, J.J.Thompson concluded from his experiments that atoms weren't solid spheres, rather that they were masses of positively charged 'pudding' and negatively charges (electrons) that he nicknamed 'plums' - hence the 'plum pudding' model
In 1909, Ernest Rutherford conducted the gold foil experiment