fundamental ideas

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  • Created by: aswaawawa
  • Created on: 11-04-15 11:31

C1.1 Fundamental ideas

  • a) All substances are made of atoms.

    • A substance that is made of only one sort of atom is called an element.

    • There are about 100 different elements.

    • Elements are shown in the periodic table.

    • Metals on the left side of the table and the non-metals are on the right side.

    • The groups contain elements with similar properties.

  • b) Atoms of each element are represented by a chemical symbol,

    • eg O represents an atom of oxygen, and Na represents an atom of sodium and others

  • c) Atoms have a small central nucleus, which is made up of protons and neutrons and around which there are electrons which move in specific energy levels (a sort of orbit, often called a shell) in the majority of the space of an atom.

  • d) Know their relative electrical charges i.e. proton is +1 and neutron 0 and the electron –1

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C1.1 Fundamental ideas

  • e) In a neutral atom, the number of electrons is equal to the number of protons in the nucleus.

    • Therefore atoms have no overall electrical charge ie overall neutral (+ balances -).

      • Removing electrons from atoms makes positive ions.

      • Adding electrons to atoms makes negative ions.

  • f) All atoms of a particular element have the same number of protons.

    • Atoms of different elements have different numbers of protons.

    • Elements consist of one type of atom only.

    • g) The number of protons in an atom of an element is its atomic number.

      • The sum of the protons and neutrons in an atom is its mass number.

    • h) Electrons occupy particular energy levels.

      • Each electron in an atom is at a particular energy level (in a particular shell).

      • The electrons in an atom occupy the lowest available energy levels (innermost available shells).

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