EDEXCEL IGCSE CHEMISTRY: DOUBLE SCIENCE 复习笔记:1.4.4 Electronic Configuration & Reactivity

EDEXCEL IGCSE CHEMISTRY: DOUBLE SCIENCE 复习笔记:1.4.4 Electronic Configuration & Reactivity

Similar Chemical Properties


Chemical properties of elements in the same group

  • Elements in the same group in the periodic table will have similar chemical properties
  • This is because they have the same number of outer electrons so will react and bond similarly
  • The group number of an element which is given on the periodic table indicates the number of electrons in the outer shell (valence electrons)
    • This rule holds true for all elements except helium; although is in group 0, it has only one shell, the first and innermost shell, which holds only 2 electrons


  • We can use the group number to predict how elements will react as the number of valence shell electrons in an element influences how the element reacts.
  • Therefore, elements in the same group react similarly
    • By observing the reaction of one element from a group, you can predict how the other elements in that group will react
    • By reacting two or more elements from the same group and observing what happens in those reactions you can make predictions about reactivity and establish trends in reactivity in that group


  • For example, lithium, sodium and potassium are in group 1 and can all react with elements in group 7 to form an ionic compound
  • The group 1 metals become more reactive as you move down the group while the group 7 metals show a decrease in reactivity moving down the group


Why Noble Gases are Unreactive


  • The elements in group 0 of the periodic table are called the noble gases
  • They are all non-metal, monatomic (exist as single atoms), colourless, non-flammable gases at room temperature
  • The group 0 elements all have full outer shells of electrons; this electronic configuration is extremely stable
  • Elements participate in reactions to complete their outer shells by losing, gaining, or sharing electrons
    • The Group 0 elements do not need to do this, because of their full outer shells which makes them unreactive and inert


  • Other than helium which has 2 electrons in its outer shell, the noble gases have eight valence electrons (which is why you may see this group labelled “group 8”)
  • Electronic configurations of the Noble gases:
    • He = 2
    • Ne = 2, 8
    • Ar =  2, 8, 8
    • Kr =  2, 8, 18, 8
    • Xe = 2, 8, 18, 18, 8







The periodic table highlighting the noble gases – they occupy the group furthest to the right