The light (dependent) reactions. Water is split into its components, hydrogen and oxygen. Gaseous oxygen is released as a by-product, the hydrogens are further split into protons and electrons, the electrons are use to replenish those lost by Photosystem II, and the protons are eventually picked up by NADP coenzyme. The coenzyme is reduced to NADPH, which is later utilized in the dark reactions to reduce atmospheric carbon dioxide.
After chemical reactions.
Elements cannot be split using chemical reactions.
Water
water
water
water
An atom. (Greek: a'tomos means 'can not be cut')
Water is split during light reactions to release oxygen.
Nuclear Reaction.
Generally in a body two type of reactions take place, catabolic and anabolic. Catabolic reactions are the type of reactions in which bio-molecules in our body split into their constituents to release energy; while anabolic reactions are those reactions in which new bio-molecules are synthesized in our Body. Together both reactions are known as METABOLISM.
Water is the molecule that is split during the light reaction of photosynthesis when releasing oxygen.