1
Q
Limitations of particle model
A
- Particles aren’t solid
- particles aren’t spheres
- Doesn’t show the size of the particles
- doesn’t show forces between particles
2
Q
Solids
A
- particles close together
- regular arrangement of particles in a lattice
- vibrate around a fixed position
- cannot be compressed
- Low energy of particles
3
Q
Liquids
A
- particles close together
- random arrangement of particles
- move around each other
- cannot be compressed
- higher energy of particles
- fill shape of container
4
Q
Gasses
A
- particles far apart
- random arrangement of particles
- move rapidly in all directions
- can be compressed
- highest energy of particles
- fill shape of container
5
Q
What is:
- solid to ⇌liquid
- Liquid to ⇌gas
- solid to ⇌gas
A
- Melting ⇌ freezing
- boiling⇌condensing
- Sublimation ⇌deposition
6
Q
physical change
A
- physical changes are reversible
- can easily be undone by heating or cooling
7
Q
Chemical reaction
A
- Hard to reverse
- when atoms are re-arranged to form new products(compounds or element)
- bonds break
*
8
Q
Examples of physical change
A
- Melting
- boiling
- freezing
- condensing
9
Q
Examples of chemical change
A
- baking a cake🎂
- cooking an egg🍳
- Burning wood 🪵
10
Q
What did John dalton discover
A
- describes atoms as solid spheres
- said that different spheres make different elements
- 19th century
11
Q
What did j.j Thompson discover
A
- disproved atoms being solid spheres
- discovered electrons
- plum pudding theory
- positively charged atom negative electrons scattered
12
Q
What did Rutherford discover
A
- 1909
- gold foil experiment
- fired positively charged alpha particles at a thin sheet of gold foil
- most particles went straight through some were deflected and some deflected backwards
- disproved Thomson by showing electrons weren’t scattered all throughout
- small positively charged nucleus surrounded by a cloud of atoms
- most of an atom is empty space
13
Q
What did Niels Bohr discover
A
- found that electrons can only exist in fixed shells with fixed energy levels in each shell
- disproves the plum pudding model as the cloud of electrons would be attracted to the nucleus causing it to collapse
14
Q
Describe how and why the atomic model has changed over time
A
- Old models were acceptable at the time as they fitted limited evidence
- the more experiments scientists do the more modification added due to new scientific knowledge
15
Q
What is peer review
A
Peer review is when other scientists review the ideas check for errors and use it to help develop their own work
16
Q
Name of subatomic particles
A
- protons
- neutron
- electron
17
Q
relative mass and charge of :
- protons
- neutrons
- electrons
A
- Protons: mass 1, charge +1
- Neutrons: mass1, charge 0
- Electrons: mass 0.0005, charge -1
18
Q
Protons
A
- heavy
- positively charged
19
Q
Neutrons
A
- Heavy
- neutral
20
Q
Electron
A
- Hardly any mass
- negatively charged
- orbit nucleus in electron shells 🐚
21
Q
The nucleus
A
- in the middle of the atom
- contains protons + neutrons
- overall positive charge
- majority of the mass 10
22
Q
Atom
A
- Nucleus in the centre containing protons and neutrons
- negative electrons orbiting in shells
- Overall charge is neutral and electrons and protons numbers are equal and balance each other out
- 10-10 size of atom in m(or 10-8 centimeters)
23
Q
What is a molecule
A
- Formed from two or more atoms
- can bc of the same element or different elements
24
Q
What is atomic number
A
Number of protons
25
Mass number
Total number of protons and neutrons
26
How to find neutron number
atomic number-mass number
27
What is an ion
* Same number of neutrons different number of protons and electrons
28
what is an isotope
* same number of protons different number of neutrons
*
29
ion examples
F- 9+1 =10
30
when do ions form
* forms when atoms gain of loose electrons
* negative=gain electrons
* positive =loose electrons
OCR Chemistry C1-C7
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