Answer: option B. electron
Explanation:
The substances are made up of atoms. The atoms combine or break apart, in what is called chemical change or chemical reaction, to form new substances (compounds when there are two or more different kind of atoms).
It is the valence electrons what determine the chemical change.
Valence electrons are the electrons that are in the outermost orbital, so it is the valence electrons of an atom which can interact with the valence electrons of other atoms. The chemical change happens when some bonds (chemical link) are broken and other are formed, which gives rise to new substances.
In a chemical bond the external electrons may be shared to form a covalent bonds or transferred to form ionic bonds. Other kind of bond is the metallic bond, in which the electrons are delocalized and move freely among a hole chain or net or metal atoms.
The nucleus and its particles, neutrons and protons, do not take an active role on the chemical reactions.
Nucleus transformations, where the protons and neutrons take part, are a different kind of reactions, called nuclear reactions.
