Solids are one of the three fundamental states of matter. The atoms or molecules in solids are held together by strong intermolecular bonds. In a crystal, the positions of molecules are fixed, thus solids do not have any rotatory or translatory motion. The molecules in solids only have vibratory motion. On the other hand liquids have weaker intermolecular forces that are stronger than that of gases. Molecules in liquids are free to move while in gases they are far apart. Liquids have definite volume but no definite shape while gases have neither definite volume nor definite shape. There are 3 types of bonding in matter that hold the molecules together:
- Covalent Bond
- Ionic bond
- Metallic bond
Covalent bond is a type of chemical bond in which sharing of valence electrons takes place between two atoms of a molecule.Covalent compounds have low melting and boiling points except in the case when polymers are formed as a result of covalent bonding (a large number of molecules are held together through covalent bonds, forming a 3D structure).
Ionic bonding generally takes place between a metal and a nonmetal. Non-metals, usually gain electrons and metals lose electrons in order to complete their octet and hence metals acquire a positive charge and non-metals acquire a negative charge during the formation of an ionic bond. The electrostatic force of attraction between the metals (positive charge) and non-metals (negative charge) results in the formation of ionic bonds.
For example: Sodium loses one electron which is acquired by chlorine atom to form sodium chloride compound having ionic bond between sodium atom and chlorine atom.
Melting point and boiling point of an ionic compound is very high as these bonds are very strong, and large amount of energy is required to break these bonds.
- Metallic bonds: Metallic bonding is the strong attractive force between the positive nuclei and the delocalised electrons. Delocalized electrons are the electrons which are not associated with a single atom. Physical properties of metals are observed due to the delocalized electrons involved in the metallic bonding.
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