Select: Research Question (strand i, Level 1-2)
State: Hypothesis / Prediction (strand ii, Level 3-4)
State the variables (strand iii, Level 1-2)
Type of Variable | Identified Value |
|---|---|
Independent | |
Dependent | |
Constant |
Design a logical, complete and safe method along with safety measures to be followed, appropriate materials and equipment to be used in the experiment. (strand iv, Level 7-8)
The Useful Halogens
Halogens are a group of elements that share similar chemical properties. Some well-known halogens are chlorine, fluorine, bromine, and iodine. Even though they may sound unfamiliar, we use them in many everyday products.
Fluorine is added to toothpaste to help protect teeth from decay. It strengthens the enamel on our teeth and keeps cavities away. Chlorine is used to clean water in swimming pools and sometimes in drinking water. It kills bacteria and makes the water safer for us.
Iodine is another important halogen. It is used in medicines and disinfectants to clean cuts and wounds. Our bodies also need small amounts of iodine for healthy growth. Bromine can be found in special fire-resistant materials. These materials can slow down or stop fires from spreading.
Although halogens can be reactive and dangerous if handled incorrectly, they are extremely useful when used in the right way. They help keep us healthy, safe, and protected in our daily lives.
Reactivity Trends in the Halogens
Halogens follow a pattern in how reactive they are. The smaller the atom, the more reactive it is. This means fluorine, at the top of the group, is the most reactive, and iodine, lower down, is less reactive. This trend helps scientists predict how halogens will behave in reactions and why some are used more carefully than others.
Halogens and Water
Some halogens can react with water. Chlorine reacts with water to form substances that kill bacteria, which is one reason it is used to clean pool and drinking water. Fluorine reacts very quickly and can even form acids. Iodine and bromine react much more slowly with water, and their changes are less noticeable. These differences fit the reactivity trend: more reactive halogens tend to react faster and more strongly with water.
Select: Research Question (strand i, Level 1-2)
State: Hypothesis / Prediction (strand ii, Level 3-4)
State the variables (strand iii, Level 1-2)
Type of Variable | Identified Value |
|---|---|
Independent | |
Dependent | |
Constant |
Design a logical, complete and safe method along with safety measures to be followed, appropriate materials and equipment to be used in the experiment. (strand iv, Level 7-8)
Refer to Periodic Table,
Study the elements of Group 17 and in below answer box construct a table to write down the reactivity with water of the first 4 elements from the group. Organise the data in the decreasing order of reactivity. (strand i, Level 5-6)
Interpret the relationship between atomic radius and the reactivity for these 4 elements.(strand ii, Level 1-2)
"The reactivity trend across group 17 decreases, while atomic radius increases from top to bottom" . State the validity of this prediction. (strand iii, Level 3-4)
Discuss your response to Q11. (strand iii, Level 7-8)
Procedure to find the boiling point of water:
Take fixed volume of water in a beaker.
Insert thermometer so it touches the top surface of water gently.
Record the initial temperature.
Gently heat the water using a hot plate.
Record the temperature every minute until water starts boiling and begins to form steam.
The method given above to find the boiling point of water is not appropriate.(strand iv, Level 3-4)
For the above experiment, we need to keep