C3 1 Development Of The Periodic Table

Key points of C3 1 Development Of The Periodic Table.

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C3 1.1 - The Early Periodic Table.

  • The periodic table of the elements, developed as an attempt to classify the elements. It arranges them in a pattern according to their properties.
  • Early versions of the periodic table failed to take account of the fact that not all of the elements were known at that time.
  • Mendeleev's table took account of unknown elements, and so provided the basis for the modern periodic table.
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C3 1.2 - The Modern Periodic Table.

  • The group that an element is in is determined by its atomic (proton) number.
  • The number of electrons in the highest energy level of an atom, determines its chemical properties.
  • We can explain trends as we go down a group, in terms of the number of energy levels in the atoms.
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C3 1.3 - Group 1 - The Alkali Metals.

  • The elements in Group 1 of the periodic table are called the alkali metals.
  • The metals all react with water to produce hydrogen and an alkaline solution containing the metal hydroxide.
  • The reactivity of the alkali metals increases as we go down the group.
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C3 1.4 - Group 7 - The Halogens.

  • The halogens exist as diatomic molecules.
  • The halogens all form ions with a single, negative charge.
  • The halogens fom covalent compounds by sharing electrons with other non-metals.
  • The reactivity of the halogens decreases going down the group.
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C3 1.5 - The Transition Elements.

  • Nearly all the transition elements have high melting points, and high densities.
  • The transition metals are strong and hard, and are good conductors of electricity and heat.
  • The transition metals do not react vigorously with oxygen or water.
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