Chemistry - C2.3

Chemistry - C2.3

1. In an Atom the number of protons = number of electrons so atoms have no overall charge

   • Mass Number = Number of Neutrons + Number of Protons
     • Number of Neutrons = Mass Number - Atomic Number
       • Atomic Number = Number of Protons

2. Isotopes = Atoms of the same element with the same number of protons but a diferent number of neutrons

   • An example of a isotope is carbon

3. Relative atomic mass compares the mass of atoms of a elements have different isotopes and is an average value

   • Is an average value because elements have different isotopes with different mass number
     • The relative atomic mass is found from a periodic table and is the big number from an element

4. Mole is the formula mass of a substance in grams

   • Number of Moles = Mass divided by Molar Mass

5. Total of each type of element in reactants = Total of each type of element in products

   • Big numbers placed infront of substances in equations only
     • Atoms are multiplied by the big number

6. % yield = (Actual Mass divided by Theoretical Mass) x 100

   • % yield = percentage of what is produced compared to what should have been produced in theory
   • Reactants can react in ways that are different to what is expected
     • Reactions may not go to completion because it is reversible
       • Some products may be lost when it is seperated

7. % mass = (Ar x number if elements x 100) divided by Mr

   • Percentage of an element in a compound is calculated using Ar and Mr

8. Mr = E (Ar x Number of Atoms)

   • Relative Formula Mass of compound is the sum of the relative atomic masses of the atoms in the formula

9. Empirical Formula = simplest whole number ratio of elements in a compound

   • Use the table to calculate
     • Write out the formula once you have worked it out

10. Balanced Symbol Equation used to find masses of any reactants of products

    • Mole quantaties are used to work out masses of substances in the reaction
      • Used to work out masses of any substances in the reaction
    • Use lumpy bicycle or reacting mass equation