Usage - Pronoun-Antecedent Agreement. A pronoun is a word used to stand for (or take the place of) a noun. A word can refer to an earlier noun or pronoun in the sentence. Example:
A subatomic particle is a unit of matter or energy that's the fundamental makeup of all matter. According to modern atomic theory, an atom has a nucleus, which is its center, or core. The nucleus contains subatomic particles: protons and neutrons. Protons are positively-charged particles. Neutrons are neutral particles.
Key Points. 1  A proton is a positively charged particle located in the nucleus of an atom. 2  An elementary charge -- that of a proton or electron -- is approximately equal to 1.6Ã10-19Coulombs. 3  Unlike protons, electrons can move from atom to atom.