Protons, Neutrons and Electrons
Protons and neutrons make up nucleus and electrons orbit it.
Proton- Relative mass- 1.0, Relative charge- 1+
Neutron- Relative mass- 1.0 Relative charge- 0
Electron- Relative mass- 1/2000 Relative charge- 1-
Number of protons = number of electrons so it is electrically neutral.
Top number- Mass number Bottom number- Atomic number
DEFENITION- Mass number- is the number of protons and neutrons in the nucleus.
DEFEITION- Atomic number- is the number of protons in the nucleus of an atom.
DEFENITION- Isotopes are atoms of the same element with the same number of protons but different number of neutrons.
Isotopes have different mass because there is a different amount of neutrons.
Different isotopes of the same element react in the same way because reactions involve electrons, neutrons make no difference.
Atomic structure of ions
DEFENITION- An ion is a positively or negatively charged atom or group of atoms.
Lose/ gain electrons.
Ions are charged because they have different numbers of protons and electrons.
Measurement of relative masses
We compare masses of different elements agaisnt the carbon- 12 isotope.
Relative isotopic mass
DEFENITION- is the mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12
Relative isotopic mass is the same number as the mass number (top number)
Relative atomic mass
DEFENITION- is the weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12
Sample of Bromine contains 53% of Br-79 and 47% of Br-81
Answer = 53/100 x 79 + 47/100 x 81= 79.94
Relative molecular mass
DEFENITION- is the weighted mean mass of a molecule compared with 1/12 of the mass of an atom of carbon-12
Can be found by adding together the relative atomic masses of each atom in a molecule. eg Cl2
Relative formula mass
DEFINITION- is the weighted mean mass of a formula unit compared with 1/12 of the mass of an atom of carbon-12
Can be found by adding together all relative atomic masses of each atom in a formula eg CaBr
ATOMS OF SUBSTANCE AND THE MOLE
Amount of substance
Amount of substance is given the unit, n
Amount of substance is based on a standard count of atoms called the Avogardo constant- is the number of atoms per mole of the carbon-12 isotope- 6.02 x 10 to the power of 23
DEFINITION- A mole is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.
DEFINITION- is the mass per mole of a substance.
Can be found by adding together all the realtive atomic masses for each atom the makes up a formula unit
n= amount of substance
M= molar mass
TYPES OF FORMULA
DEFINITION- is the simplest whole number ratio of atoms of each element in a compound.
Example: Analysis showed that 0.6075g of…