Please enable JavaScript.
Coggle requires JavaScript to display documents.
C1 (history of the atom, elements, Physical separation techniques, impure,…
C1
history of the atom
1.Daltons model- no protons, electrons or neutrons
- plum pudding model- ball of positive charge, with negative electrons inside
- alpha scattering experiment- scientists fired small, positively charged particles at a piece of gold foil a few atoms thick, expecting the atoms to pass through, some bounced back and many were deflected, to explain this scientists suggested that the positive charge and mass of an atom must be concentrated in a small space at its centre, they named this, the nucleus.
- nuclear model- electrons now orbit nucleus, not at set distances
- electron shell (bohr) model- electrons orbit nucleus at set levels, orbits called shells
- the proton- further evidence proved existence of the proton, proton has opposite charge to an electron
- The neutron- particle with no charge, found by Chadwick, called this a neutron, inside nucleus
- mass- protons and neutrons 1, electron almost 0
elements
element- substance made up of only one type of atom, cannot be broken down into simpler substances
compound- chemically bonded elements ( 2 or more), irreversible
mixture, 2 or more not chemically bonded substances, reversible reaction
groups- downwards in periodic table, same number of electrons, similar properties
periods- sideways in periodic table, same number of electron shells
-
-
-
-
conservation of mass
in a chemical reaction, chemical bonds are broken, the atoms are rearranged and the chemical bonds are made again
mass is never lost, start and finish with the same amount
-