An atom has a central, dense, tightly packed nucleus with a diameter of 10-15 m compared to an atom at 10-10 m, a size equivalent to a marble in a football stadium. Therefore, the nucleus makes up less than 0.01 % of the atom's volume.
The nucleus contains positively charged protons and neutral neutrons as subatomic particles bound firmly by the nuclear force.
Most probable kinetic energy is the energy possessed by the maximum number of reactant molecules at a temperature T, and it is shown as a peak on the Maxwell-Boltzmann energy distribution graph (fraction of molecules versus Kinetic energy).
The different spatial arrangements organic molecules adopt due to the rotation of the single bond are called conformations. A specific conformation is called a conformer or conformational isomer.
Many such conformational isomers are undoubtedly interconvertible by single bond rotations. So, these isomers are simply different rotational (or structural) arrangements of the same molecule.
Valence Bond (VB) Theory | Valence Shell Electron Pair Repulsion (VSEPR) Theory |
|---|---|
Valence Bond Theory explains how atoms combine to form di and polyatomic molecules held by covalent bonds. | VSEPR theory considers shape, molecular geometry, and bond angles as an after-effect of covalent bond formation. The molecules take up various shapes to overcome the electron repulsions between the bonding and nonbonding electrons of the combining atoms. |
Learning Objective: To study lone pair's role in chemical reactions as electron donors.
Prerequisites:
Of all the electrons that form part of an atom, the valence electrons are the only ones that participate when atoms combine to form a bond. In ionic bonding, electrons are transferred (either lost or gained), whereas in covalent bonding, two electrons are shared between the two atoms. Double or triple bonds are formed when atoms share more than one electron pair. The atoms do so to attain the stable octet configuration of 8 electrons in their valence shell.
| Qualitative Analysis | Quantitative analysis |
|---|---|---|
Aim | Identifies what compounds or functional groups are present. Therefore, the type of information obtained is descriptive. For example, whether the compound changed color, evolved gas, or formed a precipitate.
| Measures how much of a compound is present and, therefore, numerically describes its quantity. |
In his landmark paper, 'The Atom and the Molecule,' G.N. Lewis attempted to describe linkages between the atoms to understand the nature of covalent bonds.
He used dots to represent an atom’s valence electrons and argued that the atoms share their valence electrons to form one, two, or three bonds until they attain a stable octet electron configuration. An exception is the Hydrogen atom that attains a duplet configuration.
Learning Objective: To learn about the trend and order of nucleophilicity for the p-block elements in the periodic table
Prerequisites:
Electronegativity trend of the elements from the Periodic table