Which of the following pairs of atomic models represent the same element?

• A. A model with 6 protons, 6 neutrons, and 6 electrons; and a model with 6 protons, 7 neutrons, and 6 electrons
• B. A model with 1 proton, 0 neutrons, and 1 electron; and a model with 2 protons, 2 neutrons, and 2 electrons
• C. A model with 12 protons, 12 neutrons, and 12 electrons; and a model with 13 protons, 12 neutrons, and 12 electrons
• D. A model with 8 protons, 8 neutrons, and 8 electrons; and a model with 7 protons, 8 neutrons, and 8 electrons

Answer: (A)

Verified step by step guidance

1. Recall that the identity of an element is determined by the number of protons in its nucleus, which is called the atomic number (Z). Two atoms with the same number of protons belong to the same element.
2. Look at each pair of atomic models and compare their number of protons. If the number of protons is the same in both models, they represent the same element.
3. Note that the number of neutrons can vary between atoms of the same element; these variants are called isotopes. Different isotopes have the same atomic number but different mass numbers.
4. Check the first pair: one model has 6 protons, 6 neutrons, and 6 electrons; the other has 6 protons, 7 neutrons, and 6 electrons. Since both have 6 protons, they represent the same element (carbon) but different isotopes.
5. For the other pairs, identify if the number of protons differs. If it does, they represent different elements regardless of neutrons or electrons.