Due to the presence of an oxygen molecule, the chemical compound fluorenone is more polar than fluorene. The difference in electronegativity between the bonded carbon and oxygen present in fluorenone creates a dipole that increases fluorenone's polarity.
A fluorenone molecule contains 13 carbon atoms, eight hydrogen atoms and one oxygen atom. A molecule of fluorene contains 13 carbon atoms and 10 hydrogen atoms. Carbon and hydrogen differ in electronegativity only by 0.4 units and are considered nonpolar covalent bonds. The bond between carbon and oxygen is considered polar covalent due to the 1.0 difference in electronegativity. The polar covalent bond present in fluorenone creates a dipole in the molecule that is not present in fluorene; therefore, fluorenone is more polar.