P1 1 Atomic Structure/ Periodic Table

METAL NON-METAL(-ate)

• simple - used to obtain the solvent from a solution (water from salt) or two liquids with different boiling points (water from ethanol) • fractional - used to separate one liquid from a complex mixture with diff boiling points (fractions in crude oil)

• mixture is heated until the substance with the lowest boiling point boils+ turns into a gas • gas enters the condenser+ condenses into a liquid, pure substance enters the beaker • (fractional): fractionating column stops other substances from being extracted - will condense before reaching the condenser+ run back down into the flask

• filtration (insoluble solids from liquids, sand from water) • evaporation+ crystallisation (salt from a solution) • chromatography (different coloured dyes in ink) • simple distillation (water from salt, water from ethanol) • fractional distillation (fractions in crude oil)

• mass decrease - a gas is formed which escapes the container/ system into the surroundings • mass increase - atoms from a gas in the atmosphere have been added

atoms are tiny, solid, indivisible spheres

plum pudding - a ball of positive charge with negative electrons in it

nuclear model - a nucleus with positive charge, electrons that orbit, empty space in between (from alpha particle scattering experiment)

planetary model - electrons orbit in shells at fixed distances/fixed energy levels from the nucleus, empty space between

atomic model- nucleus contains positive protons and neutrons with no charge, electrons orbit nucleus at fixed distances, empty space between (discovered neutrons)

DON’T Dalton - ball TRY TO Thompson - plum pudding - electrons REMEMBER Rutherford - nuclear - protons in nucleus BRILLIANT Bohr - planetary - electrons orbit in shells CHEMISTS Chadwick - atomic - neutrons in nucleus

• nucleus containing protons+ neutrons - almost all the atom’s mass is concentrated here • electrons orbit in shells at fixed distances from the nucleus • no overall electric charge/ neutral - contain an equal no. protons+ electrons

• created by Mendeleev in 1869 • elements were placed in order of atomic weight and grouped according to chemical properties -> modern periodic table is ordered by atomic number: more accurate as atomic weight varies in isotopes • he predicted the existence of undiscovered elements+ left gaps in the table

noble gases: helium, neon, argon, xenon * full outer shells so don’t need to gain/lose electrons - therefore unreactive and exist as single atoms * boiling points increase down the group * low boiling points - gases at room temp - weak intermolecular forces * colourless/odourless

alkali metals: lithium, sodium, potassium, rubidium * one electron in outer shell * they react with oxygen (to form oxides), chlorine (to form chlorides), water (to form hydroxides) * lower densities (than most metals) * lower boiling points * form compounds that are soluble white solids * form positive ions with +1 charge * soft+ malleable * often stored in oil to stop them reacting with oxygen+ water vapour in air

• need to lose one electron to form full outer shell • as you go down the group the elements have more shells: increased distance between nucleus+outer electron so decreases electrostatic attraction between electron+nucleus protons; increased shielding effect - more inner electrons shield outer electron from electrostatic force • therefore less electrostatic force = outer electron is more easily lost = reactivity increases down the group • therefore boiling points decrease down the group

halogens: fluorine, chlorine, bromine, iodine * need to gain one electron to form full outer shell * low boiling points * form compounds that are soluble white solids * form negative ions with -1 charge * coloured * toxic * higher molecular masses as you move down group * react with metals to form the ionic compound halide salt * a more reactive halogen can displace a less reactive halogen from a salt solution

halogens: fluorine, chlorine, bromine * need to gain one electron to form full outer shell * as you go down the group the elements have more shells: increased distance between nucleus+outer shell so decreases electrostatic attraction between electron+nucleus protons; increased shielding effect - more inner electrons shield outer electron from electrostatic force * therefore less electrostatic force = outer electron is harder to gain = reactivity decreases down the group * therefore boiling points increase down the group

• good conductors of heat+electricity • high density • malleable (hammered into shape) • ductile (drawn into wires) • high melting+boiling points (except mercury) • react w non-metals forming positive ions • do not react with other metals • form basic oxides

• poor conductors of heat+electricity (except graphite) • low density • brittle (when solid) • not ductile • low melting+boiling points • react w metals forming negative ions • react w other non-metals forming molecules or compounds • form acidic oxides