As a reactive species, a methylene refers to an electron-deficient carbene, represented as :CH2.
Carbenes are carbon-containing electrophiles that contain only 6 valence electrons instead of the standard eight required for stability. It has an unshared electron pair and two bonds, making it a divalent species, highly unstable, having a fleeting existence. Though classified as electrophiles, methylene species have no formal charge and are neutral.
When atoms engage to form molecules, they do so by the overlap of atomic orbitals, creating a bigger molecular orbital that now encompasses more than one atom of a molecule.
The meta directors are a class of atoms or a group of atoms that, when attached to an aromatic ring, render it with the ability to direct an incoming electrophile to its meta (third or fifth) position in an electrophile aromatic substitution reaction.
A molecular formula expresses in positive whole numbers the total count of each atom in a molecule.
For example, in the molecular formula of H2O, the total count of Hydrogen atoms is 2, and that of Oxygen atoms is 1. Another example of a complex molecule, such as glucose, expressed in a molecular formula as C6H12O6, has a total of 6 carbon and oxygen atoms, and 12 hydrogen atoms.
A molecular formula is always a multiple of the empirical formula, and their relationship is expressed as,
The melting point of a substance is the temperature at which a solid, ordered crystalline substance is in equilibrium with a more random liquid state, thereby undergoing a phase change.
Since the components of the solid substances are bound by strong intermolecular attractive forces, it also reflects the energy needed to weaken these attractive forces and move freely in the liquid state.
Molecular mass is the sum of the masses of all the atoms in the molecule, denoted as m.
The mass of the atoms is measured in the average atomic mass unit, a weighted average of all the element's naturally occurring isotopes.
The sum is represented in amu (μ) or Da unit.
A molecule is an electrically neutral chemical entity that consists of two or more bond atoms.
The joining of two or more atoms by a linkage known as a covalent bond creates molecules such that changing the connection, or the arrangement will change the molecule and its properties.
The mass number is the total count of the number of protons and neutrons present in the nucleus of an atom, denoted as A.
For example, 12C has 6 protons and 6 neutrons; its mass number is 12.
A mass number is always a whole number. The mass number is also known as the atomic mass number or nucleon number.
A metallic solid is made of many metal atoms composed of kernels and electrons, the positive kernels held in arrays while the negative electrons float around them, at the same time, attracted to each other due to their opposite electrostatic nature and engaged in bonding known as the metallic bond.
Russian chemist Vladimir Markovnikov proposed Markovnikov’s rule in 1869 to predict the regiochemistry of addition reactions between unsymmetrical alkenes/ alkynes and hydrogen halides to form alkyl halides.
According to the rule, ‘An alkyl halide is formed in a reaction between an unsymmetrical alkene or alkyne and hydrogen halide (HX) when the negative part of the reagent (X-) attaches to the alkene carbon that has fewer number of hydrogen atoms across the double bond.’
On the dissolution of a substance in a dispersion medium, the aggregation of a vast number of atoms or smaller molecules of varying sizes (< 10-9 m) leads to the formation of colloidal particles of the size range 10-9 to 10-6 m.
As the colloidal particles are now made up of many atoms or molecules, it is now called multimolecular colloids.
The peak on the Maxwell-Boltzmann energy distribution graph (fraction of molecules versus Kinetic energy) corresponds to the most probable kinetic energy, and it is the energy possessed by the maximum fraction of the reactant molecules at a temperature T.
