C1 Flashcards
Limitations of particle model
- Particles aren’t solid
- particles aren’t spheres
- Doesn’t show the size of the particles
- doesn’t show forces between particles
Solids
- particles close together
- regular arrangement of particles in a lattice
- vibrate around a fixed position
- cannot be compressed
- Low energy of particles
Liquids
- particles close together
- random arrangement of particles
- move around each other
- cannot be compressed
- higher energy of particles
- fill shape of container
Gasses
- particles far apart
- random arrangement of particles
- move rapidly in all directions
- can be compressed
- highest energy of particles
- fill shape of container
What is:
- solid to ⇌liquid
- Liquid to ⇌gas
- solid to ⇌gas
- Melting ⇌ freezing
- boiling⇌condensing
- Sublimation ⇌deposition
physical change
- physical changes are reversible
- can easily be undone by heating or cooling
Chemical reaction
- Hard to reverse
- when atoms are re-arranged to form new products(compounds or element)
- bonds break
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Examples of physical change
- Melting
- boiling
- freezing
- condensing
Examples of chemical change
- baking a cake🎂
- cooking an egg🍳
- Burning wood 🪵
What did John dalton discover
- describes atoms as solid spheres
- said that different spheres make different elements
- 19th century
What did j.j Thompson discover
- disproved atoms being solid spheres
- discovered electrons
- plum pudding theory
- positively charged atom negative electrons scattered
What did Rutherford discover
- 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
What did Niels Bohr discover
- 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
Describe how and why the atomic model has changed over time
- 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
What is peer review
Peer review is when other scientists review the ideas check for errors and use it to help develop their own work
Name of subatomic particles
- protons
- neutron
- electron
relative mass and charge of :
- protons
- neutrons
- electrons
- Protons: mass 1, charge +1
- Neutrons: mass1, charge 0
- Electrons: mass 0.0005, charge -1
Protons
- heavy
- positively charged
Neutrons
- Heavy
- neutral
Electron
- Hardly any mass
- negatively charged
- orbit nucleus in electron shells 🐚
The nucleus
- in the middle of the atom
- contains protons + neutrons
- overall positive charge
- majority of the mass 10
Atom
- 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)
What is a molecule
- Formed from two or more atoms
- can bc of the same element or different elements
What is atomic number
Number of protons
Mass number
Total number of protons and neutrons
How to find neutron number
atomic number-mass number
What is an ion
- Same number of neutrons different number of protons and electrons
what is an isotope
- same number of protons different number of neutrons
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ion examples
F- 9+1 =10
when do ions form
- forms when atoms gain of loose electrons
- negative=gain electrons
- positive =loose electrons
