2.2 Group 2

• The atomic radius of group two elements increases as you go down the group due to the addition of extra electron shells.
• The first ionization energy of group two elements decreases as you go down the group due to the addition of extra shells, which leads to shielding and makes it easier to remove the outer electron.
• The number of protons increases as you go down the group, but the shielding effect overrides this increase.
• Melting points generally decrease as you go down the group due to the increase in the size of the metal ion and the decrease in the number of delocalized electrons.
• Metallic bonding is a characteristic of group two elements, which involves a positive metal ion and delocalized electrons or a negative sea of electrons.
• As you go down the group, the size of the metal ion increases but the number of delocalized electrons remains the same and so does the charge on the metal ion.
• This means that as the ion gets bigger but the charge and the number of electrons remain the same, the distance between the delocalized electrons and the nucleus and the positive metal ion gets bigger, weakening the attractive force and making it easier to break these bonds, resulting in a lower melting point.
• Group Two hydroxides and sulfates can be tested for using barium chloride.
• Magnesium oxide is produced when magnesium reacts with steam.
• Group Two metals are less reactive than Group One metals with water but still form hydroxides.
• Strontium reacts with water to form strontium hydroxide and hydrogen.
• Barium chloride is used to test for sulfates because it removes or reacts with any carbonates that may be in the compound, preventing a false result due to a white precipitate.
• If the anion, the negative ion, has a double charge, it becomes less soluble as we go down the group.
• Magnesium and Group Two metals react with water to form metal hydroxides.
• Group Two hydroxides and sulfates have opposite solubilities as we go down the group.
• Group Two metals react slowly with cold water but more lively when reacted to steam.
• Group Two metals form two hydroxides per group to metal atom.
• To mop up any carbonates left after testing for sulfates, a separate test is done using sodium hydroxide.
• Magnesium and barium are exceptions to the general decrease in melting points as you go down the group.