Page 46 - Chemistry_Form_2

Chemistry
for Secondary Schools

Questions
1. What happens when the powder of calcium and magnesium ribbon are
dropped in water?
2. What is the difference in the reactivities of calcium and magnesium?
FOR ONLINE READING ONLY

Group VII: Halogens

Task 2.7
Use online sources or any reliable resources to study trends in physical and
chemical properties in Group VII.

Group VII elements include fluorine (F), chlorine (Cl), bromine (Br), iodine (I),
and astatine (At). These are highly reactive non-metals. They have the following
properties:

Physical properties

(a) They exist in different physical states for example fluorine and chlorine are
gases, bromine is a liquid, and iodine is a solid.
(b) Their densities increase down the group.
(c) Their melting and boiling points increase down the group.

Chemical properties
(a) Their reactivity decreases down the group.
(b) They react with metals to form salts.

(c) They react with hydrogen to form acids (hydrogen halides).

Exercise 2.3

1. What happens to atomic size as you move down a group? Explain, giving
reasons.

2. Predict how the densities of alkali metals change as you move down Group I.
3. The reactivity of alkali metals is directly related to their atomic size. Justify.

4. Investigate the use of lithium in rechargeable batteries. How do its properties

Student’s Book Form Two 39

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CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 39