an extremely small piece of matter that is smaller than an atom or found inside an atom, such as a proton, neutron, or electron. SMART Vocabulary: related words and phrases. Physics: atoms, molecules & sub-atomic particles.
an extremely small piece of matter that is smaller than an atom or found inside an atom, such as a proton, neutron, or electron. SMART Vocabulary: related words and phrases. Physics: atoms, molecules & sub-atomic particle
