An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed due to the attraction between an atom that has lost one or more electron (known as a cation) and an atom that has gained one or more electrons (known as an anion). Usually, the cation is a metal atom and the anion is a nonmetal atom.
It is important to recognize that pure ionic bonding - in which one atom "steals" an electron from another - cannot exist: all ionic compounds have some degree of covalent bonding, or electron sharing. Thus, the term "ionic bond" is given to a bond in which the ionic character is greater than the covalent character - that is, a bond in which a large electronegativity difference exists between the two atoms, causing the bond to be more polar (ionic) than other forms of covalent bonding where electrons are shared more equally. Bonds with partially ionic and partially covalent character are called polar covalent bonds. Nevertheless, ionic bonding is considered to be a form of noncovalent bonding.
Ionic compounds conduct electricity when molten or in solution, but not as a solid. They generally have a high melting point and tend to be soluble in water.
A formation of an ionic bond proceeds when the atom of an element (usually metal), whose ionization energy is low, releases some of its electron(s) to achieve a stable electron configuration and after releasing some of its electron(s) the atom becomes a cation. The atom of another element (usually non metal), whose electron affinity is positive, then accepts the electron(s), again to attain a stable electron configuration and after accepting electron(s) the atom becomes an anion. Typically, the stable electron configuration is one of the noble gases for elements in the s-block and the p-block, and particular stable electron configurations for d-block and f-block elements. The electrostatic attraction between these two entities forms the ionic bond. It is formed to attain stable octate structure.
For example, common table salt is sodium chloride. When sodium (Na) and chlorine (Cl) are combined, the sodium atoms each lose an electron, forming cations (Na+), and the chlorine atoms each gain an electron to form anions (Cl−). These ions are then attracted to each other in a 1:1 ratio to form sodium chloride (NaCl).
Na + Cl → Na+ + Cl− → NaCl
The removal of electrons from the cation is endothermic, raising the system's overall energy. There may also be energy changes associated with breaking of existing bonds or the addition of more than one electron to form anions. However, the action of the anion accepting the cation's valence electrons and the subsequent attraction of the ions to each other releases energy and thus lowers the overall energy of the system.
Ionic bonding will occur only if the overall energy change for the reaction is favorable – when the reaction is exothermic. The larger the resulting energy change, the stronger the bond. The low electronegativity of metals and high electronegativity of non-metals means that the reaction is most favorable between a metal and a non-metal.
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.[1] For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full outer shell, corresponding to a stable electronic configuration.
Covalent bonding includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, and three-center two-electron bonds.[2][3] The term covalent bond dates from 1939.[4] The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H
2, the hydrogen atoms share the two electrons via covalent bonding.[5] Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding which entails sharing of electrons over more than two atoms is said to be delocalized.
Properties Of Ionic and Covalent bonds
Ionic Compounds
Crystalline solids (made of ions)
High melting and boiling points
Conduct electricity when melted
Many soluble in water but not in nonpolar liquid
Covalent Compounds
Gases, liquids, or solids (made of molecules)
Low melting and boiling points
Poor electrical conductors in all phases
Many soluble in nonpolar liquids but not in water
It is important to recognize that pure ionic bonding - in which one atom "steals" an electron from another - cannot exist: all ionic compounds have some degree of covalent bonding, or electron sharing. Thus, the term "ionic bond" is given to a bond in which the ionic character is greater than the covalent character - that is, a bond in which a large electronegativity difference exists between the two atoms, causing the bond to be more polar (ionic) than other forms of covalent bonding where electrons are shared more equally. Bonds with partially ionic and partially covalent character are called polar covalent bonds. Nevertheless, ionic bonding is considered to be a form of noncovalent bonding.
Ionic compounds conduct electricity when molten or in solution, but not as a solid. They generally have a high melting point and tend to be soluble in water.
A formation of an ionic bond proceeds when the atom of an element (usually metal), whose ionization energy is low, releases some of its electron(s) to achieve a stable electron configuration and after releasing some of its electron(s) the atom becomes a cation. The atom of another element (usually non metal), whose electron affinity is positive, then accepts the electron(s), again to attain a stable electron configuration and after accepting electron(s) the atom becomes an anion. Typically, the stable electron configuration is one of the noble gases for elements in the s-block and the p-block, and particular stable electron configurations for d-block and f-block elements. The electrostatic attraction between these two entities forms the ionic bond. It is formed to attain stable octate structure.
For example, common table salt is sodium chloride. When sodium (Na) and chlorine (Cl) are combined, the sodium atoms each lose an electron, forming cations (Na+), and the chlorine atoms each gain an electron to form anions (Cl−). These ions are then attracted to each other in a 1:1 ratio to form sodium chloride (NaCl).
Na + Cl → Na+ + Cl− → NaCl
The removal of electrons from the cation is endothermic, raising the system's overall energy. There may also be energy changes associated with breaking of existing bonds or the addition of more than one electron to form anions. However, the action of the anion accepting the cation's valence electrons and the subsequent attraction of the ions to each other releases energy and thus lowers the overall energy of the system.
Ionic bonding will occur only if the overall energy change for the reaction is favorable – when the reaction is exothermic. The larger the resulting energy change, the stronger the bond. The low electronegativity of metals and high electronegativity of non-metals means that the reaction is most favorable between a metal and a non-metal.
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.[1] For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full outer shell, corresponding to a stable electronic configuration.
Covalent bonding includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, and three-center two-electron bonds.[2][3] The term covalent bond dates from 1939.[4] The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H
2, the hydrogen atoms share the two electrons via covalent bonding.[5] Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding which entails sharing of electrons over more than two atoms is said to be delocalized.
Properties Of Ionic and Covalent bonds
Ionic Compounds
Crystalline solids (made of ions)
High melting and boiling points
Conduct electricity when melted
Many soluble in water but not in nonpolar liquid
Covalent Compounds
Gases, liquids, or solids (made of molecules)
Low melting and boiling points
Poor electrical conductors in all phases
Many soluble in nonpolar liquids but not in water
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