Chemistry Unit 1 (just notes)


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  • Created by: Sara
  • Created on: 30-01-13 17:58


Same number of protons & electrons, different number of neutrons.

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Relative Atomic Mass

The average mass of all isotopes compared to the mass of an atom of carbon-12.

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Atomic & Proton Number

Atomic number: protons + neutrons

Proton number: protons (same as electrons)

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A mole of a substance is defined by the amount of substance that contains as many particles as atoms in 12g of carbon-12 (Avogadro's constant).

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Avogadro's constant

The number of atoms in 12g of carbon-12: 6.02 x 10^23

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Moles formula

Number of moles = mass in grams / molar mass in g/mol

mol = g / ram

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Relative Molecular Mass

Sum of all the relative atomic masses of the atoms in one molecule.

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Molar mass

The mass of ONE MOLE of a substance (g/mol) - Relative atomic mass.

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Mol & gases

1 mole of any gas occupies 24 dm^3  at 25ºC and 1 atm (298K).

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