Question

Na-23 has 12 neutrons. What is it’s atomic number?

Answer 1

Answer:

11

Explanation:

The atomic number = number of protons. The mass number (23) = sum of number of neutrons and protons. Since you know the mass number is 23 and it has 12 neutrons, 23-12 gives you 11 protons, so its atomic number is 11.

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Answer 2

Answer:

11 Protons

Explanation:

Na-23 shows the mass of the element as 23. Therefore subtract 12 neutrons from the mass to get # of protons which is = to atomic #.