1.2 Amount of Substance
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How do you know a chemical reaction has taken place?
Colour change Effervescence Temperature Light Precipitate formed (cloudy) Change in mass Sound pH change
What do the small numbers represent within an equation?
They say how many atoms of that element are within the molecule
What is the Mr?
Relative Molecular Mass The average mass of a molecule compared to 1/12 of the mass of one atom of carbon-12
What is the Ar?
Relative Atomic Mass Average mass of an atom compared to 1/12 of one atom of carbon-12
What is used to compared relative masses?
The carbon 12 scale
What unit is used for Mr?
gmol ^-1
How do you calculate the Mr?
Add up all the atomic mass numbers in the molecule
How to work out percentage of an element within a compound?
Ar of element Divided by Mr of compound Multiplied by 100
How do you work out the transition element charges?
They should be given to you as a roman numeral I - 1+ II - 2+ III - 3+ IV - 4+ Etc....
Definition of an element?
A substance in which all the atoms contain the same number of protons
Definition of an atom?
The smallest part of an element that can take part in a chemical reaction
Definition of an ion?
An atom that has either lost electrons to form a positive ion or gained electrons to form a negative ion Atoms do this to make a full outer shell of electrons
Definition of a molecule?
The smallest particle of a compound (a combination of two or more elements) Also a name for elements that cannot exist as atoms in a free state
Which elements cannot exist as atoms in a free state?
Diatomic molecules Hydrogen - H2 Nitrogen - N2 Chlorine - Cl2 Iodine - I2 Oxygen - O2 Fluorine - F2 Bromine - Br2
What is the charge of ammonium?
NH4 ^ 1+
What is the charge of chloride, bromide and iodide?
Cl ^ 1- Br ^ 1- I ^ 1-
What is the charge of hydroxide?
OH ^ 1-
What is the charge of nitrate and nitrite?
NO3 ^ 1- NO2 ^ 1-
What is the charge of hydrogen carbonate and hydrogen sulphate?
HCO3 ^ 1- HSO4 ^ 1-
What is the charges of sulphate, sulphite and sulphide?
SO4 ^ 2- SO3 ^ 2- S2 ^ 1-
What is the charges of oxide, carbonate and phosphate?
O2 ^ 1- CO3 ^ 2- PO4 ^ 3-
What does aqueous mean?
Dissolved in water
What are the symbols for: hydrochloric acid Sulphuric acid Nitric acid Ethanoic acid
HCl H2SO4 HNO3 CH3COOH
What are the symbols for ammonia Carbon monoxide Sulphur dioxide Methane
NH3 CO SO2 CH4