Chemistry

Water is generally clear and transparent but minerals and the concentration of chemicals make it soft or hard water. Soft water produces a good lather with soap and hard water does not. Hard water contains chlorides and sulphides of magnesium and calcium. Therefore, water dissolves many salts of divalent cations like Mg2+, Ca2+, and anions like Cl-, SO42-, HCO3-. Hardness is of two types.

Temporary hardness is due to the presence of bicarbonates of calcium and magnesium. Permanent hardness is due to sulphates and chlorides. Temporary hardness can be treated by boiling and Clark’s method. Permanent hardness can be treated by washing soda and by using sodium zeolite.

There has been a wide range of atomic models throughout the history of atomic physics, that refers primarily to a period from the beginning of the 19th century to the very first half of the 20th century. Here are some standard atomic models.

According to Dalton, an atom is an indivisible and dense sphere. Atoms of the very same elements are alike. They combine various methods to form compounds.

Universally everything tends to be more stable. Atoms gain stability by attaining the electronic configuration of noble gases. The 2 or 8 electrons in the valence shell represent the stability of the atom.

So, the atom follows the duplet rule, attaining 2 electrons or octet rule, attaining 8 electrons in the valence shell. They acquire stability by sharing electrons, obtaining electrons, or giving electrons.  So, for this purpose atoms have different types of chemical bonding.

The chemical bond is basically the force of attraction between atoms that holds them. Chemical bonds are of four types 1) Ionic bond 2) Covalent bond 3) Metallic bond and 4) Coordinate Covalent Bond.

The elements of Group-13 to Group-17 when permitted to react with each other, they form a chemical bond by mutual sharing of their valence shell electrons. This type of bond, which is formed due to the mutual sharing of electrons, is called a covalent bond.

A molecule is the smallest particle of a pure compound which can exist independently. It may include several atoms. The number of atoms present in a molecule identifies its atomicity.

Chemistry, the science that deals with the properties, composition, and structure of substances, the changes they go through, and the energy that is emancipated or absorbed during these processes.