Which element is a metalloid and has 14 neutrons in its most common isotope?

• A. Phosphorus (P)
• B. Aluminum (Al)
• C. Germanium (Ge)
• D. Silicon (Si)

Answer: (D)

Verified step by step guidance

1. Identify the atomic number (number of protons) of each element given: Phosphorus (P), Aluminum (Al), Germanium (Ge), and Silicon (Si). The atomic number corresponds to the number of protons in the nucleus.
2. Recall that the number of neutrons in an isotope is calculated by subtracting the atomic number from the mass number (total protons + neutrons). Use the formula: \(\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}\).
3. Determine the most common isotope for each element by rounding the atomic mass to the nearest whole number to find the mass number.
4. Calculate the number of neutrons for each element's most common isotope using the formula from step 2, and identify which element has 14 neutrons.
5. Recall the definition of a metalloid: elements with properties intermediate between metals and nonmetals. Among the elements listed, identify which one is classified as a metalloid and matches the neutron count found.