modern periodic table

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  • Created by: siobhan
  • Created on: 18-05-13 10:25
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  • The modern periodic table
    • Scientists found out about protons and electrons at the start of the 20th century. Soon after this, they developed models of the arrangement of electrons in atoms. The elements were arranged in the periodic table in order of their atomic numbers and were lined up in vertical groups
    • The groups of elements have similar chemical properties because their atoms have the same number of electrons in the outer shell. For the main groups, the number of electrons in the outer shell is the same as the group number.
    • Within a group the reactivity of the elements depends on the total number of electrons. Going down a group theire are more outer shell and the atoms get larger
      • as the atoms get larger, the electrons in the outer shell are less strongly attracted to the nucleus.
    • When metals react they lose electrons, so the reactivity of metals in a group increases going down a group
      • When non-metals react the gain electrons, so the reactivity of non-metals decreases going down a group
    • When non-metals react the gain electrons, so the reactivity of non-metals decreases going down a group

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