An element is identified by the number of what particles in its nucleus?

An element is primarily identified by the number of protons in its nucleus, a characteristic known as the atomic number. This number determines not only the identity of the element but also its position in the periodic table. For example, hydrogen has one proton, while carbon has six protons. The properties of the element, including its chemical behavior, are influenced by the number of protons because they determine the electronic structure of the atom.

Electrons, which are negatively charged particles, play a crucial role in chemical interactions and bonding but do not determine the element's identity on their own. Neutrons, while important for the stability of the nucleus and influencing the mass of the atom, do not affect its fundamental classification as an element. The phrase "nucleus count" is not a recognized way to define the identity of an element. Thus, protons are the key particles for identifying distinct elements.