C3.1 - Introducing chemical reactions Flashcards
Why are the formulae of metal elements always written as empirical formulae? (2)
- because they exist as giant metallic lattices
- numbers in the formula would be too big
ie. C 432625 H 736765 N 63910
are the non-metal elemis in group 0 diatomic atoms?
no, they exist as individual atoms
what is special about the elements in group 7?
they are all diatomic (expect astatine)
list all the diatomic molecules (7)
Hydrogen. remember as: Have No Fear Of Ice Cold Beer Nitrogen Fluorine Oxygen Iodine Chlorine Bromine
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give examples of a simple covalent compound
- Carbon dioxide
- methane
- water
explain (in terms of particles), why the mass of the solid increases when copper is heated in the air (3)
- copper atoms react with oxygen atoms in the air
- forms a copper oxide (chemical reaction)
- therefore, mass increases since the solid is made of copper ions and oxygen ions
explain what is meant by the law of conservation of mass
the principle that states that the total mass stays the same during a chemical reaction, because atoms are not created or destroyed
what is a non-enclosed system?
when substances can leave or enter the reaction mixture (usually in an open container)
what is a closed system?
- a container where no substances can enter or leave during the reaction
what do half equations show?
- the change that happens to one reactant in a chemical reaction
define the term ‘mole’
the amount of any substance that contains the same number of entities as there are atoms in 12.0g of carbon-12
define the term ‘Avogadro’s constant’
the number of entities in 1 mole (6.02 x 10^23)
what terms are the same as molar mass?
- relative atomic mass
- relative formula mass
what is molar mass measured in?
grams per mole (g/mol)
