The cast of chemicals: cytosol and extracellular fluid, water is the main ingredient of the fluid inside the neuron, the cytosol, and the, electrically charged atoms are dissolved in this water extracellular. They are responsible for the resting and action potentials: water bonds, ions. The most important property of the water molecule is its uneven distribution of electrical charge. Because of this property, the oxygen atoms in water acquire a net negative charge. Water is said to be a polar molecule, held together by polar covalent. Atoms or molecules that have a net electrical charge are known as ions. Ions with a net positive charge are called cations. Ions with a negative charge are called anions. Ions are the major charge carriers involved in the conduction of electricity in biological systems: the phospholipid membrane, substances with uneven electrical charges will dissolve in water, compounds whose atoms are bonded by non-polar covalent bonds have no.