Summary AQA GCSE Chemistry Combined Science - Atomic Structure and the Periodic Table Notes

ATOMIC STRUCTURE AND PERIODIC
TABLE
ATOMIC STRUCTURE
 Atoms: the smallest part of an element that can exist
 Compounds: when two or more elements are chemically joined
o They are held together by chemical bonds and are difficult to separate
 Mixtures: two or more elements or compounds that are not chemically joined
o They are easy to separate
 Isotopes: an element with the same number of protons but a different number of neutrons
 Types of particles
o Proton:
 Relative mass: 1
 Charge: +1
o Neutron:
 Relative mass: 1
 Charge: 0
o Electron:
 Relative mass: very small
 Charge: -1
 Mass number = number of protons + number of neutrons
 Relative atomic mass = (% abundance of isotope 1 x mass of isotope 1) + (% abundance of
isotope 2 x mass of isotope 2)/100




HISTORY OF THE ATOM
 John Dalton
o Start of the 19th century
o Discovered the atom, described it as a solid sphere
 JJ Thomson
o 1897
o Plum pudding model – the atom is a ball of charge with electrons scattered
throughout it
 Ernest Rutherford
o 1909
o Mass is concentrated at the centre of an atom
o The nucleus is charged and is most of the mass
o Most atoms are empty space
 Niels Bohr
o 1911