Yr 9 Chemistry- Atomic Structure

sub-atomic particles

proton, neutron, electron

relative CHARGE, MASS and LOCATION of each sub-atomic particle

proton: +1 charge, 1, in the nucleus

Neutron: 0 charge, 1, in the nucleus

Electron: -1 charge, 1/2000, in shells orbiting the nucleus

John Dalton's Atomic Theory (1803)

Atoms are small, indivisible particles

JJ Thomson (1897)

plum pudding- electrons embedded in a sphere of positive charge, no nucleus

Rutherford (1912)

NUCLEAR MODEL Positively charged nucleus, bc the positive alpha particles were fired at thin gold foil. Most went thru the foil, but a few occasionally repelled in diff directions, suggesting a positively charged, DENSE nucleus. Electrons surrounded the nucleus and occupied most of the volume.

Bohr

a small positively charged nucleus is surrounded by revolving negatively charged electrons in shells in fixed orbits

J Chadwick

Discovered the neutron in the nucleus

Isotope

Atoms of the same element that have the same atomic number but diff mass number. (DIFF NEUTRONS, SAME PROTONS)

Relative atomic mass (Ar)

The weighted mean mass of the isotopes of the element compared with 1/12 of the mass of an atom of carbon-12 atom

formula to find amu (relative atomic mass)

(a/100 b) + (c/100 d)

Cations

ions with positive charges

formed when atom loses electrons

usually metals (on the left)

more protons than electrons

Anions

ions with negative charges

formed when atom gains electrons

usually non-metals (right)

more electrons than protons

BIG 5 IONS

nitrate

sulphate

carbonate

hydroxide

ammonium

Nitrate Formula

NO3-

Sulfate Formula

SO4 2-

Carbonate Formula

CO3 2-

Hydroxide formula

OH-

Ammonium Formula

NH4+