Group-2 Elements: Alkaline Earth Metals
Chapter Name : The S- Block Elements |
Sub Topic Code : 102_11_10_07_04 |
Topic Name : Group-2 Elements: Alkaline Earth Metals |
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Sub Topic Name : Hydration Enthalpies |
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Introduction
• Group 2 includes beryllium, magnesium, calcium, strontium, barium and radium. • These elements with the exception of beryllium are commonly known as the alkaline earth metals. • Like alkali metal ions, the hydration enthalpies of alkaline earth metal ions decrease with increase in ionic size down the group. • The hydration enthalpies of alkaline earth metal ions are larger than those of alkali metal ions. • Thus, compounds of alkaline earth metals are more hydrated than those of alkali metals, • E.g., MgCl2 and CaCl2 exist as MgCl2.6H2O and CaCl2• 6H2O while NaCl and KCl do not form such hydrates.
Pre-Requisites:
Alkali earth metals, elements, periodic table, hydration enthalpy
Activity:
Bones and teeth have calcium in them.
Real Life Question:
Where do you find calcium in the body?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Alkaline earth metals | • Group 2 elements. |
Learning aids / Gadgets
| Gadgets | How it can be used |
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| Periodic table | Look at the elements present in the group 2 of the periodic table. |
Real life uses :
Calcium is important for the bone and teeth development.
Places to visit :
Kitchen.
Practical examples around us
| Examples | Explainations |
|---|---|
| Milk, yogurt | These are rich sources of calcium. |
What you learn in Theory:
• Like alkali metal ions, the hydration enthalpies of alkaline earth metal ions decrease with increase in ionic size down the group. • The hydration enthalpies of alkaline earth metal ions are larger than those of alkali metal ions. • Thus, compounds of alkaline earth metals are more hydrated than those of alkali metals. • E.g., MgCl2 and CaCl2 exist as MgCl2.6H2O and CaCl2• 6H2O while NaCl and KCl do not form such hydrates.
What you learn in Practice:
• Important ions for the body like calcium and magnesium belong to group 2 in the periodic table.