Why hydroxide ions have a negative charge

One water molecule gains a hydrogen and therefore takes on a positive charge, while the other water molecule loses a hydrogen atom and therefore becomes negatively charged. OH - is called a hydroxyl ion and it makes things basic. However, in water, there is a balance between hydroniums and hydroxyls so they cancel each others' charges.

Pure water is neither acidic or basic; it is neutral. So how does something become acidic or basic? That happens when the hydroniums and the hydroxyls are out of balance. If there are more positively charged hydroniums than negatively charged hydroxyls, then the substance is acidic. If there are more negatively charged hydroxyls than positively charged hydroniums, then the substance becomes basic.

Watch out for that, and ask for clarification! When we dissolve acids in water, we create an excess of hydroniums. When we dissolve bases in water, we create an excess of hydroxyls.

Here are two examples. Now let's look at lye, a strong base with the chemical formula NaOH sodium hydroxide. The sodiums don't do anything important, but the hydroxyls make the solution more basic. One last question: Why are strong acids and strong bases so nasty? Copper will be produced because copper is less reactive than hydrogen. Oxygen is produced from hydroxide ions , unless halide ions chloride, bromide or iodide ions are present. In that case, the negatively charged halide ions lose electrons and form the corresponding halogen chlorine, bromine or iodine.

The table summarises the product formed at the anode during the electrolysis of different electrolytes in solution.

Predict the product formed at the positive electrode during the electrolysis of concentrated sodium sulfate solution. Oxygen will be produced. Electrolysis of dissolved ionic compounds An electrolyte formed by dissolving an ionic compound contains: hydrogen ions from the water, and positive ions from the compound hydroxide ions from the water, and negative ions from the compound The ions compete at each electrode to gain or lose electrons.

At the cathode Whether hydrogen or a metal is produced at the cathode depends on the position of the metal in the metal reactivity series : the metal is produced at the cathode if it is less reactive than hydrogen hydrogen is produced at the cathode if the metal is more reactive than hydrogen The reactivity series of metals - carbon and hydrogen are non-metals, shown for comparison Question Predict the product formed at the negative electrode during the electrolysis of sodium chloride solution.

Reveal answer up. Sodium atoms have 11 electrons. Two of these are in the lowest energy level, eight are in the second energy level and then one electron is in the third energy level. This is a very unstable arrangement, and the element sodium is a highly reactive, deadly white semi-solid that will burst into flames on exposure to the air or will burn through human flesh on contact.

A reactive substance. Chlorine atoms have 17 electrons. Two in the lowest, eight in the second and 7 in the third energy level. This too is a very unstable arrangement. This element is a gas at room temperature and was used in World War One as a poisonous attack weapon because of its high reactivity with human lungs. These two atoms were made for one another. Sodium atoms readily give up the single electron in the outermost orbital. This electron is immediately picked up by a chlorine atom and fitted into the last empty space in its outermost orbital.

Now both atomic arrangements are much more stable. They both have outermost orbitals which are filled with electrons. However, there is a price to be paid for this stability. In giving up an electron, the sodium atom has lost a negative electrical charge.