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LC Chemistry
LC Chemistry
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LC Chemistry

All Chemistry Definitions to Learn for Leaving Certificate - Higher Level

The Atom

  • Dalton’s Atomic Theory: All matter is made up of indivisible atoms which cannot be created or destroyed.
  • William Crookes discovered the Electron. Cathode ray tube.
  • JJ Thomson determined that electrons were negative. Found E/M ratio.
  • Robert Millikan’s Oil drop experiment discovered size of electron’s charge.
  • Plum Pudding Model: Solid positive sphere with electrons embedded.
  • Rutherford discovered the Nucleus. Fired alpha particles at gold foil. Proton.
  • Chadwick discovered the neutron by firing alpha particles at beryllium.
  • Energy level is the fixed energy value that an electron in an atom may have.
  • Heisenberg’s Uncertainty Principle states that it is... (More)

From looking at the past papers about 90% of the marks for Biology can be gained from knowledge of all the definitions and theory. Most questions are not direct definitions but theory questions like "describe the..." and "draw the...". Direct definitions are about 20% of the paper. As the paper is mostly theory based, calculations are quite rare unlike chemistry and physics.

For chemistry on the other hand the marks are more mixed up. I would say about 55 - 60% can be gained from definitions and theory while the rest come from calculations. The first few lab experiment and... (More)

Chemical Bonding Notes

  • Compound: two or more different elements combined together chemically
  • Octet Rule: when bonding occurs, atoms tend to reach an electron arrangement with 8 electrons in the outermost energy level
  • Ion: a charged atom or group of atoms
  • Ionic bonding: the force of attraction between oppositely charged ions in a compound. Formed by the complete transfer of an electron from one atom to another
  • molecule: a group of atoms joined together, the smallest particle of an element with can exist independently
  • valency: the number of atoms of hydrogen (or any monovalent element) with which each atom of the element combines
  • Transition... (More)

I am not sure about the exact percentages but its definitely biology. And for biology, you can get asked a definition in any part of the exam.