The identity of a chemical element is determined by which of the following?

• A. The atomic mass of the atom
• B. The number of protons in the nucleus
• C. The number of neutrons in the nucleus
• D. The number of electrons in the atom

Answer: (B)

Verified step by step guidance

1. Understand that the identity of a chemical element is defined by a unique characteristic of its atoms.
2. Recall that atoms consist of protons, neutrons, and electrons, each with different roles.
3. Recognize that the atomic mass depends on both protons and neutrons, but it can vary due to isotopes, so it does not uniquely identify the element.
4. Know that the number of electrons can change in ions, so it also does not define the element's identity.
5. Conclude that the number of protons in the nucleus, also called the atomic number, uniquely determines the identity of a chemical element.