Group 17 Elements
Chapter Name : The P- Block Elements |
Sub Topic Code : 102_12_07_18_05 |
Topic Name : Group 17 Elements |
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Sub Topic Name : Electron Gain Enthalpy |
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Introduction
• Halogens have maximum negative electron gain enthalpy in the corresponding periods. • This is due to the fact that the atoms of these elements have only one electron less than stable noble gas configurations. • Electron gain enthalpy becomes less negative down the group. • However, the negative electron gain enthalpy of fluorine is less than that of chlorine. • It is due to small size of fluorine atom. • As a result, there are strong interelectronic repulsions in the relatively small 2p orbitals of fluorine and thus, the incoming electron does not experience much attraction.
Pre-Requisites:
Periodic table, elements, electron gain enthalpy
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 have maximum negative electron gain enthalpy in the corresponding periods. • This is due to the fact that the atoms of these elements have only one electron less than stable noble gas configurations. • Electron gain enthalpy becomes less negative down the group. • However, the negative electron gain enthalpy of fluorine is less than that of chlorine. • It is due to small size of fluorine atom. • As a result, there are strong interelectronic repulsions in the relatively small 2p orbitals of fluorine and thus, the incoming electron does not experience much attraction.
What you learn in Practice:
• Halogens have maximum negative electron gain enthalpy in the corresponding periods. • This is due to the fact that the atoms of these elements have only one electron less than stable noble gas configurations. • Electron gain enthalpy becomes less negative down the group. • However, the negative electron gain enthalpy of fluorine is less than that of chlorine. • It is due to small size of fluorine atom. • As a result, there are strong interelectronic repulsions in the relatively small 2p orbitals of fluorine and thus, the incoming electron does not experience much attraction.