OCR GCSE Chemistry Notes | C1
OCR GCSE Chemistry Notes for Topic C1 - Particles, guaranteed to get you a GRADE 9
- Solids: particles are close together and vibrate in neat rows and columns.
- Liquids: particles are close together and they move slowly.
- Gases: particles are far apart, moving at random speeds and directions.
- Chemical changes require a chemical reaction; the products are different from the reactants.
- Physical changes require energy.
- The particle model does not take into account: forces between particles, the size of particles, and space between them.
- Changes of state: melting, evaporating, condensing, freezing, sublimation (solid to gas).
- Dalton said: each element has unique atoms, they can't be divided.
- Thomson: plum pudding model; positve ball with negative electrons dotted around.
- he disproved that atoms can't be split using cathode-ray tube showing small particles inside an atom.
- Rutherford: positive nucleus and negative electrons around.
- Bohr said: electrons occupy shells.
- Geiger & Marsden: carried Rutherford's experiment (shot alpha particles at gold foil). Most particles went straight through, few deflected and reflected proving that most of the atom is empty space.
- An atom is a positive nucleus surrounded by negatively charged electrons (2, 8, 8), with the nuclear radius much smaller than that of the atom and with most of the mass in the nucleus.
- Atomic radii: 10-10m.
- Relative Mass: Proton (1), Neutron (1), Electron (0)
- Relative Charge: Proton (+1), Neutron (0), Electron (-1)
- Top number on periodic table: mass number (protons and neutrons)
- Bottom number: proton number (no. of protons or electrons)
- The number of protons is the same as the number of electrons for an uncharged element.
- Ion: charged particle (gained or lost electrons).