Amongst the various types of solids - metallic, ionic, covalent - the molecular solid is a type that is differentiated from the rest based on its intermolecular attractive strength.
A molecular solid is composed of distinct, unconnected molecules that are held together by weak van der Waals forces or Hydrogen bonds rather than stronger ionic or covalent bonds.
Following the footsteps of Gilbert N. Lewis in understanding the nature of the covalent bond, Linus N. Pauling stumbled upon an interesting observation.
Pauling noticed that the nature of the chemical bond could be explained using a scale or continuum.
Atom, the omnipresent component that builds up all the stuff the universe is made of, has its identity tied to the tiny, sub-atomic particle- the proton(s). The proton number decides the type of atom; however, the atom’s reactivity is determined by an outer-nuclear component- the electrons.
In nuclear reactions, the proton number can change so that an atom's identity also changes. However, only the electron count changes in organic chemical reactions without affecting an atom's identity.
| Addition Reaction | Elimination Reaction | |
|---|---|---|
Process | Two molecules combine in an addition reaction to form a single addition product (adduct).
|
| Types of Interactions | Shown By | Energy (KJ/mole) | Examples (Image) |
|---|---|---|---|
| Ion-Ion | Only Ions (E.g.- Na+Cl- or carboxylate ion and ammonium ion) | 400-4000 |  |
| n- | iso- | neo- | sec- or s- | tert- or t- | |
|---|---|---|---|---|---|
| Stands for | normal | isomer | Greek for new | secondary | tertiary |
| Structure | The carbon chain is continuous without any branching; therefore, it represents a straight-chain alkane. | Iso- prefix indicates branching of the straight chain alkane.
|
| sp3 | sp2 | sp |
|---|---|---|---|
Orbitals involved |
The molecule H2N-NH2, also known as hydrazine, each Nitrogen atom has 3 bond pairs (two N-H and one N-N bonds) and one lone pair. So, the steric number of each Nitrogen atom is,
steric number=number of bond pairs + number of lone pairs
steric number=3 + 1 = 4
Carbon has the atomic number 6, which also equals the number of electrons. According to the rules determining electronic configuration (Aufbau, Pauli, and Hund), these electrons are arranged in the 1s, 2s, and 2p subshells of the Carbon atom to give the complete electronic configuration - 1s2 2s2 2p2. This electronic configuration of Carbon, where the electrons are in their lowest energy states and closest to the nucleus, is called the ground state electronic configuration.
The bond angle is the angle at which two adjacent bonds converge and meet at the central atom in molecules.
For example, the angle between H-C-H in the CH4 molecule is the bond angle, and C is the central atom. Similarly, the H-O-H is the bond angle in water, with Oxygen being the central atom.