Dont keep a define shape as they flow in the bottom of the container
If you cool it it will freeze and become a solid
If you heat it, it will evaporate and become a gas.
Gases
No force of attraction
Dont have a define shape
Take the shape of the container
Move constantly with random motion
The hotter the gas= the faster they move
They will either expand or their pressure would increase when heated
They would condense if they cool down and then become a liquid
Physical change
They can go through to a different state of matter and go back to the original state
Chemical change
This is hard to reverse, as bonds between atoms break and the atoms change places- the atoms from the substances you start off with rearrange themselves to form different products
Atomic structure
John Dalton
19th century
Described atoms as solid spheres and that sphere made up different elements.
J.J Thomson
Plum Pudding Model
Atoms are made up of electrons
Rutherford
1909
Conducted the gold foil experiment with students Geiger and Marsden
They fired positive alpha particles at a thin sheet of gold.
They found out that some of the particles did go straight through. However, some was deflected more than expected and small number were deflected BACKWARDS.
His theory: The Nuclear Atom. In this there is a positive charged nucleus at the centre surrounded by a cloud of electrons
Bohr
Suggested that electrons can only exist in fixed orbits and not anywhere in between. This was supported by many experiments.
Isotopes are atoms with different numbers of neutrons