Chemical Bonding and Molecular Structure

Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications.

This option is correct because the more electronegative atoms are able to remove the electron density of the nitrogen atom, making it the least basicity feature of the nitrogen halides.

This option is correct because calcium fluoride is a colourless insoluble solid, the compound crystallised in cubic motif calcium cation are coordinates being centered in a box for eight fluoride ions center. Both cations and anoins are closely packed to each other due to its nature that melts at high temperature (1418⁰C).

A quadruple bond is a type of chemical bond between two atoms involving eight electrons. This bond is an extension of the more familiar type double bonds and triple bonds. Stable quadruple bonds are most common among the middle members transition metal elements such rhenium, tungsten, molybdenum and chromium.

A dipolar bond, also known as dative covalent bond or coordinate bond is a kind of 2-centre, 2-electron covalent bond in which the two electrons derive from the same atom. Typically, a dipolar bond is formed when a Lewis base donates a pair of electrons to a Lewis acid.

Hyperconjugation is the interaction of the electrons in a sigma bond (usually C-H or C-C) with an adjacent empty (or partially filled) non-bonding p-orbital or antibonding π orbital or filled π orbital, to give an extended molecular orbital that increases the stability of the system. Only electrons in bonds that are β to the positively charged carbon can stabilize a carbocation by hyperconjugation.

The term hapticity is used to describe how a group of contiguous atoms of a ligand are coordinated to a central atom. Hapticity of a ligand is indicated by the Greek character 'eta', η.

A symmetric hydrogen bond is a special type of hydrogen bond in which the proton is spaced exactly halfway between two identical atoms. The strength of the bond to each of those atoms is equal. It is an example of a 3-center 4-electron bond.

A water-activated battery is a disposable reserve battery that does not contain an electrolyte and hence produces no voltage until it is soaked in water for several minutes.

Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste.

Thiirane, more commonly known as ethylene sulphide, is the cyclic chemical compound with the formula C₂H₄S. It is the smallest suphur-containing heterocycle. Like many organosulphur compounds, this species has a stench. Thiirane is also used to describe any derivative of the parent ethylene sulphide.

Manganese tetrafluoride is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

Diethylzinc is an organozinc compound composed of zinc bonded to two ethyl groups. This colourless liquid is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane or toluene.

CFCs (Chlorofluorocarbons) contain both Chlorine and Fluorine atoms bonded to Carbon. These compounds were widely used in refrigeration and aerosols before being phased out due to ozone damage.

The Gauche effect characterizes any gauche rotamer which is actually more stable than the anti rotamer.This effect is present in 1,2-difluoroethane (H₂FCCFH₂) for which the gauche conformation is more stable by 2.4 to 3.4 kJ/mole in the gas phase. Another example is 1,2-dimethoxyethane. In stereochemistry, gauche interactions hinder bond rotation.