the nature of substances and chemical reactions

the nature of substances and chemical reactions

1. Element

   • Definition:An element contains only one type of atom
   • Elements are the building blocks of all matter - they cannot be broken down into smaller substances by chemical means.

2. compound

   • A compound contains more than one type of atom.Eg Water is made out of 2 hydrogen atoms and one oxygen atom, this makes H2O
   • Definition: A compound is created when 2 or more different atoms chemically join together

3. formulae

   • the formulae tells us how many elemant are present in the compound

4. mixture

   • A mixture is an impure substance that is made up different elemants and compunds.
   • physical properties
     • a physical property is used to observe and describe a substance eg its colour, state , density,texture and overall apperence

5. relative atomic mass

   • the relative atomic mass is a measure of the mass of one atom of the element.

6. calculating the percentage compositions of compunds

   • if we have a compound we can calculate the percentage of each of the elemants within the compound using the Ar of the elements and the Mr of the compound

7. calculating the percentage yeild

   • to calculate the percentage yeild you divide the actual yeild by the theoretical yeild and times it by 100

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