Anuska Bashyal

Resonance is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by a single Lewis formula. A molecule or ion with such delocalized electrons is represented by several resonance structures.

When it is possible to write more than one equivalent resonance structure for a molecule or ion, the actual structure is the average of the resonance structures. But resonance structures represent different ways of...

P-hydroxy benzaldehyde is more soluble in water than o-Hydroxy benzaldehyde, because P-Hydroxy benzaldehyde can form hydrogen bonds with water molecules resulting in enhanced solubility.

Hybridization may be defined as the phenomenon of combining of orbitals of an atom of nearly equal energies, giving rise to entirely new orbitals equal in number to the mixing orbitals having same energy and identical shapes. 

By valence bond theory, only half filled orbitals can take part in bonding. 

Hybridization was introduced to explain molecular structure when the valence bond theory failed to correctly predict them.

Taking example of a CH₄ molecule,

without...

The type of bond present in ice are: 1. Covalent bond    2. Hydrogen bond

The simultaneous electrostatic attraction between rhe kernels and the mobile electrons which holds the kernels together is called metallic bond. 

It is a weak bond. 

Electrons here are delocalized. 

It causes metals to display the following characteristics. 

1. Electrical Conductivity 

2. Thermal conductivity 

3. Luster 

4. Malleable and ductile 

When the constituent particles of a solid are molecules, they are called molecular solids.

They are held together by either: 

• Van der Waal's forces
• Dipole-dipole interaction 
• Hydrogen bonding

Hydrogen bond is the bond that exists between a hydrogen of a molecule (which is bonded with a strong electronegative atom) with another highly electronegative atom. 

It may be between within a molecule, molecules of same species, or molecules of different species. 

Types of hydrogen...

Intermolecular forces, often abbreviated to IMF, are the attractive and repulsive forces that arise between the molecules of a substance. These forces mediate the interactions between individual molecules of a substance. 

Van der Waals bond is weak intermolecular forces that are dependent on the distance between atoms or molecules. 
It is the attraction between instantaneous dipole and induced dipole. 

Dipole moment is the product of magnitude of the charge (q) and the distance between the centre (d) of the charges is called dipole moment. 

It is usually denoted by μ. 

The factors affecting dipole moment are: 

• Polarity of molecule.
• Magnitude of charge.
• Geometry of molecule.

The VSEPR theory explains that the approximate shape of the molecule can be predicted from the number of electron pairs in the valence shell of the central atom. 

The postulates of the VSEPR theory are listed below: 

• In polyatomic molecules one of the constituent atoms is the central atom to which all other atoms are linked.
• The total number of valence shell electron pairs (lone pair and bond pair) decides the shape of the molecule.
• The electron pairs are oriented in a way that...

Resonance is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by a single Lewis formula.

A molecule or ion with such delocalized electrons is represented by several resonance structures. Resonance structures represent different ways of placing electrons on the atoms in a molecule's Lewis dot structure. 

It is possible to write more than one equivalent resonance structure for a molecule or ion, the actual...

1.  H2O2

2. KNO3

3. HCO3- 

4. NH₄-

The formal charge of an atom is the difference between the number of valence electrons of that atom in the free state and the number of electrons given to that element in Lewis structure.

It is given by

Ammonium sulfate 

1. CH₄

2. H₂O

 -------->

3. NH₃

  ------>

a). KNO3     

b). P2O3 

At the molecular level, salt dissolves in water due to the fact that both water and salt compounds are polar, with positive and negative charges on opposite sides in the molecule.

The positively-charged side of the water molecules are attracted to the negatively-charged chloride ions and the negatively-charged side of the water molecules are attracted to the positively-charged sodium ions. 

Also, ionic bonds are non directional in nature since they are arranged in a lattice structure where...

Ionic compounds are formed by the transfer of electrons between two atoms that creates charge in them. The compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.

Atoms of elements other than noble gas have unstable electronic configuration (outermost shell is incomplete). They can lose, gain or share electrons and are chemically active. 
The tendency of atoms of various elements to acquire stable configuration of the nearest noble gas is the cause of chemical combination.

The postulates of Electronic Valence Theory are:

• The valence electrons take part in the formation of a covalent bond.
• Atoms with 8 electrons in their valence shell are most...