Group 2 Elements

Total no. of electrons in .
Electronic configuration according to molecular orbital theory:

Temporary hardness is due to presence of bicarbonates of (II) and (II). Temporary hardness is removed by adding lime water or milk of lime. This method is known as Clark's process. Removal of hardness is called softening of water.

Portland cement gets its strength from chemical reactions between the cement and water. The process is known as hydration.
Chemical composition of portland cements are-