GCSE Physics paper 1

Dalton’s model of the atom

• small, indestructible sphere

• all atoms in an element are the same

• the atoms in one element are different  from the atoms in all other elements

JJ Thomson’s model of the atom

• he discovered electrons

• the plum pudding model

Ernest Rutherford’s model of the atom

• nearly all of the atom’s mass is concentrated in the centre

• positively charged nucleus

• negatively charged electrons orbit the nucleus

Rutherford, Geiger & Marsden’s experiment

alpha particles (+) fired at thin gold foil

Niels Bohr’s model of the atom

• discovered that electrons orbit the nucleus in specific energy levels

• better than Rutherford’s model, because the atom would collapse otherwise

Diameter of the atom

1 × 10⁻¹⁰ m

Density

Conservation of mass

the principle that when a substance changes state, the number of molecules in that substance doesn’t change and neither does its mass.

Particles in a solid

• very close

• arranged in a regular pattern

• vibrate about fixed positions

Particles in a liquid

• close together

• NOT in an arranged pattern

• able to slide past each other

Particles in a liquid

• very far apart

• move randomly at high speeds

Heating curve

Specific heat capacity

the quantity of energy required to raise the temperature of 1kg of a substance by 1˚C.

Specific latent heat

the quantity of energy required to change the state of a substance with no change in temperature.