Atomic structure & The Periodic Table

• the proton has a charge of +1 and a mass of 1
• a neutron has a charge of 0 and a mass of 1
• an electron has a charge of -1 and a mass of 1/2000
• an isotope is an atom of the same element with the same number of protons but a different number of neutrons
• an ion is a charged atom that has either gained or lost electrons
• a mixture is a substance that contains two or more elements or compounds that are not chemically combined
• a compound is a substance made up of two or more elements that are chemically combined
• an element is a substance containing only one type of atom
• separation techniques - chromatography, filtration, crystalisation, simple and fractional distillation
• chromatography is used to separate mixtures of different solubilities
• filtration is used to separate an insoluble solid from a solution
• crystallisation is used to separate a solute from its solution
• simple distillation is used to separate a solvent from a solution
• fractional distillation is used to separate a mixture of liquids into two or more liquids
• the Plum Pudding model consists of negatively charged electrons in s a ball of positive charge
• The nuclear model consisted of a tiny positive nucleus surrounded by negatively charged electrons
• Bohr's nuclear model consisted of a nucleus with protons and neutrons, that is surrounded by shells of negative electrons that orbit the nucleus, and are attracted to the positive nucleus
• Mendeleev's periodic table was missing the noble gases (group 0)
• the reactivity in group 1 increases down the group, as the electrons get further away from the nucleus meaning their attraction weakens so it is easier to lose electrons
• the reactivity in group 7 decreases down the group as the number of shells increases, so there is greater distance between electrons and the nucleus so it becomes harder to gain electrons as the attraction is weaker
• the Alkali metals (group 1) are highly reactive, and the boiling and melting points decrease down the group