OCR Gateway C4

Nucleus

positive centre of atom made form protons and neutrons

atomic number

number of protons in an atom

mass number

total number of protons and neutrons

proton

subatomic particle with mass of 1 and a positive charge

neutron

subatomic particle with mass of 1 and no charge

electron

subatomic particle with mass of 0.0005 and a negative charge

electron shell

the first can hold two, the second eight and the third eight

isotope

have the same atomic number but different mass number because they have the same number of protons but different number of neutrons

element

made from same type of atoms

compound

made from at least two different elements chemically joined togther

group

vertical column on periodic table - have similar chemical properties - have same number of electrons in outer shell

period

horizontal row on periodic table

ionic

type of bond formed when metals lose elctrons and non-metals gain electrons to get full outer shells

covalent

type of bond formed when non-metals share pairs of electrons to get full outer shells

metallic

type of bond with close packed positive metal ions and delocalised electrons

electrostatic

attraction between ions

giant ionic lattice

large regular three dimensional structure of positive and negative ions

alkali metals

group 1 on the periodic table

orange

flame colour of a substance containing sodium

lilac

flame colour of a substance containing potassium

red

flame colour of a substance containing lithium

Halogens

Group 7 on the periodic table

green gas

appearance of chlorine

brown liquid

appearance of bromine

grey solid

appearance of iodine

blue

colour of copper compounds

green

colour of iron(II) compounds

orange/brown

colour of iron(III) compounds

carbon dioxide

gas formed with the metal oxide when metal carbonated thermally decompose

precipitation

a reaction between solutions that makes an insoluble product

superconductor

material that conducts with little or no resistance

sedimentation

first step in water purification - bits drop to the bottom

filtration

second step in water purification - used sand

chlorination

third step in water purification - kills microbes

distillation

method for purifying salt water - rarely used as it needs huge amounts of energy

Lead

soluble compounds that can remain in water, it comes from pipes

nitrates

soluble compounds that can remain in water, it comes from fertilisers

white

colour of precipitate formed with silver nitrate and chloride ions

cream

colour of precipitate formed with silver nitrate and bromide ions

yellow

colour of precipitate formed with silver nitrate and iodide ions

sulfates

substances that give a white precipitate when barium chloride is added