Which neutral atom has 5 valence electrons and 7 neutrons?

• A. Fluorine-16 (F, atomic number 9)
• B. Nitrogen-12 (N, atomic number 7)
• C. Oxygen-13 (O, atomic number 8)
• D. Phosphorus-18 (P, atomic number 15)

Answer: (C)

Verified step by step guidance

1. Identify the number of valence electrons for each element by using its position in the periodic table. The number of valence electrons for main group elements corresponds to the group number. For example, nitrogen (N) is in group 15, so it has 5 valence electrons.
2. Check the atomic number of each element to determine the number of protons, which equals the number of electrons in a neutral atom. For example, oxygen (O) has an atomic number of 8, so it has 8 protons and 8 electrons.
3. Calculate the number of neutrons for each isotope by subtracting the atomic number (number of protons) from the mass number (given after the element symbol). For example, oxygen-13 has 13 (mass number) - 8 (atomic number) = 5 neutrons.
4. Compare the number of valence electrons and neutrons for each option to find the atom that has exactly 5 valence electrons and 7 neutrons. Remember, valence electrons depend on the element's group, and neutrons depend on the isotope's mass number.
5. Confirm that the correct atom matches both criteria: 5 valence electrons and 7 neutrons. This will identify the correct neutral atom from the given options.