C1 - Particles Flashcards
What constitutes as a particle?
- Atoms
- Ions
- Molecules
What are the properties of a solid?
- Regular lattice particle arrangement
- Particles are very close
- Particles vibrate about fixed positions
What are the properties of a liquid?
- Random particle arrangement
- Particles are close together with some gaps
- Particles move around each other
What are the properties of a gas?
- Random particle arrangement
- Particles are far apart
- Particles move quickly in all direction
In which state(s) can something not be compressed?
A substance in solid/liquid state cannot be compressed because there is no space for particles to move into.
Why can substances in the solid state not flow?
A solid substance cannot flow as it has a fixed shape. Particles vibrate about fixed positions and do not move.
Why do solids expand when heated?
When heated, particles in a solid gain kinetic energy and vibrate more. The space between the particles increase as a result, making the solid ‘expand’.
What is a Physical change?
A reversible change that doesn’t result in a new substance being formed.
What happens to the particles in a physical change?
During a physical change, the arrangement and movement of the particles change.
What is a Chemical change?
An irreversible change where new substances are formed.
What happens to the particles in a physical change?
During a chemical change, particles break their bonds and join in different ways, resulting in new substances to be formed.
What are the limitations of the particles model?
These three things are not taken into account:
- The forces between particles.
- The size of particles.
- The space between particles.
Define ‘molecule’.
Two or more atoms chemically joined together.
What are the relative atomic masses of:
Protons, Neutrons and Electrons.
Protons - 1
Neutrons - 1
Electrons - 0.0005 (1/2000)
What are the relative atomic charges of:
Protons, Neutrons and Electrons.
Protons: +1
Neutrons: 0
Electrons: -1
Define ‘isotope’.
A different atomic form of an element where atoms of an element have the same number of protons and electrons, but a different number of neutrons.
Order Of Scientists - Developing the Atomic Model
- John Dalton - 1803
- JJ Thomson - 1897
- Ernest Rutherford - 1909
- Niels Bohr - 1913
What did Dalton suggest?
- All matter is made from atoms.
- All atoms of an element are identical.
- Different elements have different types of atoms.
- Tiny solid balls.
What did Thomson do?
- Development of the ‘Plum Pudding Model’.
- Shot beams of ‘cathode rays’ - their direction changed in electric/magnetic fields.
- Concluded atoms are spheres of positive charge, scattered with elections.
- Atoms are overall neutral.
What did Rutherford do?
- Gold foil experiment, fired beams of positively charged alpha particles at thin sheets of gold.
- Contrary to what should’ve happened (particles go straight through), many were deflected.
- A positively charged mass in the centre of the nucleus (called nucleus)
- Electrons orbit the nucleus like planets do the sun.
What did Bohr do?
- He realised that orbiting electrons would be attracted to the oppositely charged nucleus, collapsing the atom.
- Bohr suggested electrons occupied fixed energy levels (electron shells), around the nucleus.
