P1 - Matter Flashcards
1
Q
what was Dalton’s model of the atom + his thoughts
A
- small indestructible sphere
- thought that:
> all atoms in an element are the same - different elements have different atoms
2
Q
what was JJ Thompson’s model of the atom + what he thought
A
- Plum Pudding model
> described the atom as a weak positive solid sphere with negative electrons embedded into it
> found this after an experiment which polluted cathode rays
3
Q
what was Rutherford’s model like + how did he find out
A
- alongside two younger scientists they fired positive alpha particles at a thin sheet of gold
> found that most went through
> some deflected
> some completely rebounded - concluded that the atom is mostly empty space with most of its mass in the positive nucleus with electrons orbiting around
4
Q
what was Bohr’s model
A
- electrons exist in fixed shells which orbit around the nucleus
5
Q
what is the size of an atom
A
10 *-10 m
6
Q
what is the size of a nucleus
A
10*-15 m
7
Q
what is the size of a molecule
A
10*-8 m
8
Q
how was the existence of neutrons + protons discovered
A
- by deep elastic scattering
> high speed electrons were fired at nucleus of atoms which showed diffraction pattern + showed that there was sub-structure to the nucleus of an atom
9
Q
what is density
A
- tells you how much mass in contained within a volume
10
Q
what’s the equation for density
A
density = mass / volume
kg/m3 = kg / m3
11
Q
how do you find the density of an irregular shape
A
- fill eureka can with water until spout + place measuring cylinder under it
- measure mass of object
- slowly lower object into can
- water will be displaced + come out of spout because of objects more density
- the displaced water is measured and converted to m*3
- find density using equation
11
Q
what is temperature + what’s it measured in
A
- the average kinetic energy of particles
- degrees Celsius or K (Kelvin)
12
Q
what is thermal energy store + what’s it measured in
A
- thermal energy depends on the arrangement of particles + how fast they are moving / vibrating
- measured in joules
13
Q
what happens when you heat things up
A
- increase the energy stored
- produce a change of state
- make chemical reactions happen
14
Q
what are physical changes
A
- you don’t make new substances
> reversible e.g. changes of state
14
Q
what are chemical changes
A
- involve atoms joining together in diff ways
> can’t easily reverse e.g. burning
15
Q
why do solids have the most density
A
- because the particles are tightly packed together so there is more mass per unit volume
> gases have lowest density
15
Q
what is specific heat capacity
A
- the amount of energy needed to raise a 1kg substance by 1 degrees Celsius
