Diagonal relationship
It refers to the similarities in properties shown by the first element of a group to the second element of second period. e.g., Li to Mg, Be to Al, B to Si etc

Dibasic
Compounds containing two hydrogens that may be replaced by a monovalent metal or radical. An alcohol that has two hydroxyl groups, e.g., ethylene glycol.

Diborane
B2H6, a colourless, volatile compound that is soluble in ether; boiling point – 92.5ºC, melting point – 165.5ºC; can be used to produce pentaborance and decaborance, proposed for use as rocket fuels; also used to synthesize organic boron compounds. Also known as boroethane; diboron hexahybride.

Dichromate (VI)
A salt containing the ion Cr2O7. Dichromates are strong oxidizing agents.

Dichromic acid
H2Cr2O7, an acid known by in solution, especially in the form of dichromates.

Dielectric constant
Reciprocal of the force of attraction between two electric charges of unit value separated by a distance of 1 centimerter.

Dielectric properties
A dielectric is a substance in which an electric field gives rise to no net flow of electric charge. The substance having dielectric properties shows piezoelectric effect.