Periodic Trends In Properties Of Elements
Chapter Name : Classification Of Elements And Periodicity In Properties |
Sub Topic Code : 102_11_03_07_04 |
Topic Name : Periodic Trends In Properties Of Elements |
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Sub Topic Name : Electron Gain Enthalpy |
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Introduction
• When an electron is added to neutral gaseous atom to convert it into a negative ion, the enthalpy change taking place is called electron gain enthalpy. • Electron gain enthalpy becomes more negative from left to right in a period as the effective nuclear charge increases from left to right across a period. • Electron gain enthalpy becomes less negative as we go from top to bottom in a group. This is because added electron would be farther away from nucleus.
Pre-Requisites:
Element, valence shell, enthalpy, principal quantum number
Activity:
Large number of negative charges would repel more as they are close to each other, less number of negative charges would repel less.
Real Life Question:
Would negative charges closer to each other repel more or negative charges far from each other repel more?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| electron gain enthalpy | When an electron is added to neutral gaseous atom to convert it into a negative ion, the enthalpy change taking place is called electron gain enthalpy. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Magnet | A piece of metal kept far away from a magnet is easier to remove than a piece of metal kept close to it. |
Real life uses :
Negative charges kept close to each other would repel more than the ones kept far away from each other.
Places to visit :
School – opposite magnets placed close to each other would repel more than the ones placed far away from each other.
Practical examples around us
| Examples | Explainations |
|---|---|
| Magnet | It is easier to remove metal kept a distance away from a magnet than the one kept close to it. |
What you learn in Theory:
• When an electron is added to neutral gaseous atom to convert it into a negative ion, the enthalpy change taking place is called electron gain enthalpy. • Electron gain enthalpy becomes more negative from left to right in a period as the effective nuclear charge increases from left to right across a period. • Electron gain enthalpy becomes less negative as we go from top to bottom in a group. This is because added electron would be farther away from nucleus.
What you learn in Practice:
Electron gain enthalpy becomes more negative as we move from left to right across a period and as we move from bottom to top in a group.