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Chemical Bonds
Definitions of Chemical Bonds;A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms.The bond is caused by the electrostatic force of attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction.The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as dipole–dipole interaction , the London dispersion force and hydrogen bonding .
Types of Chemical Bonds:
Ionic Bonds Covalent Bonds Metallic Bonds
Ionic BondsIs a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions . These ions represent atoms that have lost one or more electron (known as cations ) and atoms that have gained one or more electrons (known as an anions ).
In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complex nature.
Properties of Ionic bondsPhysical Properties: Solid
Electrical conductivity:
Solid: No
Liquid: Yes Aqueous: Yes (if soluble)
Boiling point and Melting Point: High
Solubility in water: Often high
Thermal conductivity: Low
Examples of Ionic Bonds:
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− → NaClMolecular ions like NH4
+ or SO42-
Covalent BondsAre formed when two non metal interacts form a bond. Since both elements have the same tendency to accept e- a bond is formed by sharing e- between the two atoms. 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.
The term covalent bond dates from 1939.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 H2, the hydrogen atoms share the two electrons via covalent bonding.Covalence is greatest between atoms of similar electro negativities.Thus, covalent bonding does not necessarily require that the two atoms be of the same elements, only that they be of comparable electro negativity.Covalent bonding that entails sharing of electrons over more than two atoms is said to be delocalized.
COVALENT BOND
A covalent bond forming H2 (right) where two hydrogen atoms share the two electrons.Early concepts in covalent bonding arose from this kind of image of the molecule of methane. Covalent bonding is implied in the Lewis structure by indicating electrons shared between atoms.
Examples of Covalent Bonds:
For example, the bond formed between two Cl atoms form Cl2 is covalent, covalent bonds are also found between C and H, c and c, and cl etc.
Metallic Bond
The bond production due to the combination of electrostatic force of attraction between the electron and the positive nuclei of metal atom’s is called metallic bond.
Properties of metallic bondConductivity: Solid and liquid metals conduct heat and electricity.
Melting point : In general, metals have high melting and boiling points because of the strength of the metallic bond.
Malleable and ductile : Metals are malleable and ductile.
Optical Properties : Metals typically have a shiny, metallic lusture .
Example Of Metallic Bond
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Presented by Liton AhmedDepartment Of Textile EngineeringDaffodil International University