Group 17 Elements
Chapter Name : The P- Block Elements |
Sub Topic Code : 102_12_07_18_07 |
Topic Name : Group 17 Elements |
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Sub Topic Name : Physical Properties |
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Introduction
• Halogens display smooth variations in their physical properties. • Fluorine and chlorine are gases. • Bromine is a liquid. • Iodine is a solid. • The melting and boiling points steadily increase with atomic number. • All halogens are coloured. • This is due to absorption of radiations in visible region which results in the excitation of outer electrons to higher energy level. • By absorbing different quanta of radiation, they display different colours. • F2, has yellow, Cl2 , greenish yellow, Br2, red and I2, violet colour.
Pre-Requisites:
Periodic table, elements, Physical Properties
Activity:
See weeds have iodine in them.
Real Life Question:
Where does chlorine gas come from?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| group | Group is the vertical column on the periodic table which contains elements having the similar properties. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Chlorine disinfectant | Chlorine is used as a disinfectant. |
Places to visit :
Beach.
Practical examples around us
| Examples | Explainations |
|---|---|
| Sea weed, chlorine disinfectant | Sea weed has iodine in it. |
What you learn in Theory:
• Halogens display smooth variations in their physical properties. • Fluorine and chlorine are gases. • Bromine is a liquid. • Iodine is a solid. • The melting and boiling points steadily increase with atomic number. • All halogens are coloured. • This is due to absorption of radiations in visible region which results in the excitation of outer electrons to higher energy level. • By absorbing different quanta of radiation, they display different colours. • F2, has yellow, Cl2 , greenish yellow, Br2, red and I2, violet colour.
What you learn in Practice:
• Halogens display smooth variations in their physical properties. • Fluorine and chlorine are gases. • Bromine is a liquid. • Iodine is a solid. • The melting and boiling points steadily increase with atomic number. • All halogens are coloured. • This is due to absorption of radiations in visible region which results in the excitation of outer electrons to higher energy level. • By absorbing different quanta of radiation, they display different colours. • F2, has yellow, Cl2 , greenish yellow, Br2, red and I2, violet colour.