C1 + C2 Atomic Structure and the periodic table

• protons have a positive charge and a mass of 1
• neutrons have no charge and a mass of 1
• electrons have a negative charge and no mass
• Ernest Rutherford did the alpha particle experiment
• the alpha particle experiment proved the atom was mostly empty space because most of the particles passed straight through
• the alpha particle experiment proved there is a concentration of positive charge in the atom because like charges repel and a small number of the alpha particles were deflected
• number of neutrons=mass number-atomic number
• the atomic number is the number of protons
• the mass number is the number os protons + neutrons
• is an atom gains or looses an electron it becomes charged and is called an ion
• isotopes are forms of the same element with different relative atomic masses so a different number of neutrons but the same number of protons
• fractional distillation is a process to separate miscible liquids of different boiling points
• filtering is a method to separate an insoluble solid from a liquid
• crystallisation is a method to separate a soluble liquid from a solution (the liquid is evaporated slowly until crystals appear)
• distillation is a method to separate a liquid from a solution
• group 1 are alkali metals
• alkali metals are very reactive with oxygen and their reactivity increases as you go down the group
• alkali metals have a low density so they float on water and can be cut with a knife
• alkali metals are shinny until they react with oxygen and a layer of oxide is formed
• alkali metals burn vigorously forming smoke and a flame
• Group 1 metals are so reactive because they only have 1 electron in their outer shell to loose to have a full outer shell
• when alkali metals react with water they form hydrogen and a hydroxide
• metal + oxygen -> metal oxide
• reactivity increases as you go down group 1 because the number of electron shells increases so the attraction between the electron and the nucleus is weaker and less energy is required to loose it
• group 7 elements are called halogens
• halogens have 7 electrons in their outer shell
• halogens form ionic bonds with metals by gaining an electron to become a halide ion
• halogens become less reactive as you go down the group because there are more electron shells so weaker attraction between the electrons and the nucleus so more energy is needed to gain one
• a more reactive halogen will displace a less reactive halide from a solution of it's salt
• transition metals are good conductors and have a high density and high melting point
• transition metals are less reactive than group 1 so they make good catalysts and can form more than 1 type of ion
• group 1 and 2 form white compounds and are colourless in solutions
• the melting points of group 1 metals are lower than transition metals