· Each atom is made from protons, electrons and neutrons.
· Protons and neutrons make up the nucleus.
· Electrons orbit the nucleus.
· Protons have a positive charge and a mass of 1.
· Neutrons have no charge and have a mass of 1.
· Electrons have a negative charge and a mass of 1/2000 (negligible).
· Isotopes are atoms of the same element with different numbers of neutrons.
· The atomic number is the number of protons in the nucleus of an atom.
· The mass number is the total number of particles (protons and neutrons) in the nucleus of an atom.
· Different isotopes of the same element react in the same way.
o Chemical reactions involve electrons
o Neutrons make no difference to chemical reactivity.
· An ion is a positively or negatively charged atom or group of atoms.
· Relative isotopic mass is the mass of an atom of an isotope relative to 1/12th the mass of an atom of carbon-12.
· Relative atomic mass is the weighted mean mass of an atom of the isotopes of an element relative to 1/12th the mass of an atom of carbon-12.
· Relative molecular mass is the weighted mean mass of a molecule relative to 1/12th the mass of an atom of carbon-12.
· Relative formula mass is the weighted mean mass of a formula unit compared to 1/12th the mass of an atom of carbon-12.
Amount of substance and the mole
· Avogadro Constant = 6.02 x 1023
· The number of moles = mass ÷ molar mass.
Types of formula
· Empirical formula shows the smallest ratio of atoms in a molecule.
o It is used for compounds with giant structures like NaCl and SiO2.
· Molecular formulae show the actual number of atoms in a molecule.
o It is used to show simple molecules like C3H8
Moles and gas volumes
· At room temperature and pressure (RTP) one mole of a gas takes up approximately 24.0 dm3
· Therefore, the volume of gas per mole of gas molecules is 24.0…