1. THE PERIODIC TABLE Objectives To be able to identify groups and periods in the periodic table To know the positions of group1, group 0 and group 7 in the periodic table To know the positions, properties and uses of the halogens Read through the slides and then complete the linked worksheets

2. THE PERIODIC TABLE The rows across the elements in the periodic table are called periods The columns down are called groups. The groups are numbered from 1 to 8 Group 8 is also called group 0.

3. SOME GROUPS Group 1 are found on the far left side and are called the alkali metals Group 7 are found at the right hand side and are called the halogens. Group 8 are also known as group 0 and are called the noble gases

4. GROUP 7 These elements are all non- metals. They are also called the halogens They are:- Fluorine Chlorine Bromine Iodine

5. They have low melting points (this means that the change from a solid to a liquid at a low temperature) They do not conduct electricity They go around as pairs of atoms. We call them diatomic molecules We write them like this Fluorine - F 2 Chlorine - Cl 2 Bromine - Br 2 Iodine - I 2

6. What are they like? Fluorine is a very pale yellow gas Chlorine is a green gas Bromine is a dark red brown liquid Iodine is a black shiny solid

7. THE REACTIONS OF THE HALOGENS The halogens like to take part in chemical reactions The react with metals to make salts The most reactive halogen is fluorine and the least reactive is iodine. They get less reactive as you go down the group most reactive Least reactive The halogens like to take part in chemical reactions The react with metals to make salts The most reactive halogen is fluorine and the least reactive is iodine. They get less reactive as you go down the group

8. Uses of the halogens Iodine is used as an antiseptic Chlorine is used in swimming pools to kill bacteria Fluorine is used in tooth paste Bromine is used photographic film

9. Click here Click here and complete the worksheet Click here to complete the reactions of the halogens Click here

10. Click here to go to part 3