Elements in group 7 are referred to as Halogens.

Groups 7

Halogens

As you can tell by their position on the periodic table they are all non-metals. This means their physical properties are very similar to non-metals (they are brittle and poor conductors of heat).

Halogens are also reactive. All the elements from fluorine down to astatine, react vigorously with iron.

In the video to the right, we add iron and into a chronicle flask full of chlorine. The reaction creates iron chloride, a red smoke.

Combining iron and bromine would create iron bromide while Iron and iodine would react iron iodide.

However, as we move down the group, the reaction becomes less intense (This is the opposite to alkali metals).

The video to the left, shows the different reactions of chlorine, Bromine and Iodine.

Halogens are also very reactive with group 1 metals.  

If we combine sodium (group 1) with Chlorine (group 7) we create sodium chloride (salt).

The video to the left shows this. In this video the sodium reacted with the chlorine in the air to create sodium chloride. At the end, we can see a small piece of sodium chloride where the sodium used to be.

Alkali metals and halogens go extremely well with each other, because while one needs to loose one electron from its outer shell, the other need to gain one electron.

Displacement reaction

Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions.

Confused about what a displacement reaction is? Lets break it down.

A displacement reaction is between different elements, with different reactive levels.

Lets look at Chlorine and Bromide. Looking at the periodic table we know that Chlorine is more reactive than Bromide, because its closer to the top.

Lets combine Sodium and Bromine to create Sodium Bromide.

If we react Chlorine with sodium bromide, the chlorine will kick off (displace) the bromide (since it is less reactive) and create Sodium Chloride.

Too sum up, if a reactive element (Chlorine) comes into contact with the compound (Sodium Bromide) of a less reactive element (Bromide) a chemical reaction may take place. The less reactive element is removed from the compound and replaced by the more reactive element (Sodium Chloride).

Question

1. The following elements are placed in order from most reactive to least reactive.

Potassium

Calcium

Tin

Lead

Silver

Platinum

Using the information above, predict what the new compound formed will be (a, has been done for you).

                a. Lead Oxide + Potassium → Lead + Potassium Oxide

                b. Silver Nitrate + Tin → _______ + _______ ______

                c. Platinum Phosphate + Calcium → _______ + ______ ______

                d. Calcium Carbonate + Potassium → _______ + ______ ______

                e. Tin Oxide + Calcium → _______ + ______ ______

                f. Tin Nitrate + Platinum → _______ + ______ ______

                g. Potassium Nitrate + Silver → _______ + ______ ______

2. Using your knowledge of halogens, complete the following reactions.

               a. Sodium Bromide + Chlorine → _______ + ______ ______

               b. Sodium iodide + Bromine → _______ + ______ ______

               c. Potassium Chloride + Chlorine → _______ + ______ ______

              d. Potassium Chloride + Iodine → _______ + ______ ______

Click here for instruction on how to make a poster on the uses of group 7