Formaldehyde (CH2O) is a small organic molecule with a carbonyl group (C=O) attached to a hydrogen atom. It is a polar molecule, meaning it has an uneven distribution of electron density due to the difference in electronegativity between carbon and oxygen.
Formaldehyde is soluble in water primarily because of its ability to form hydrogen bonds with water molecules. Water is a highly polar molecule, with the oxygen atom being more electronegative than the hydrogen atoms. The partial positive charge on the hydrogen atoms in water can interact with the partial negative charge on the oxygen atom of formaldehyde, resulting in hydrogen bonding. These intermolecular hydrogen bonds between water and formaldehyde molecules facilitate the dissolution of formaldehyde in water.
However, it is important to note that formaldehyde is not an ionic compound. Ionic compounds typically consist of positively and negatively charged ions held together by electrostatic forces. In the case of formaldehyde, the bonding within the molecule is covalent, involving the sharing of electrons between carbon, oxygen, and hydrogen atoms.