Question

using the periodic table, elaborate the difference between the number of electrons in an oxygen-16 atom and an oxygen-18 atom.
a these configurations differ in their number of electrons - so they contain 8 and 9 electrons, respectively.
b allotropes vary in their number of electrons - so oxygen-16 and oxygen-18 contain 8 and 10 electrons, respectively.
c oxygen atoms fluctuate in their number of electrons - so oxygen-16 and oxygen-18 contain 7 and 9 electrons, respectively.
d the number of electrons are the same for all isotopes of an element - so both oxygen-16 and oxygen-18 contain 8 electrons.

Explanation:

To determine the correct option, we analyze each choice:

• Option A: Different electron configurations imply different elements (since electron number = atomic number). Oxygen has atomic number 8, so it can't have 9 electrons. Eliminate A.
• Option B: Allotropes are different forms of the same element (e.g., O₂ and O₃), not related to isotopes (which differ in neutrons). Also, oxygen - 16 and 18 are isotopes, not allotropes, and they have the same electron number (8). Eliminate B.
• Option C: The number of electrons in an atom is equal to its atomic number (for neutral atoms). Oxygen has atomic number 8, so oxygen atoms (neutral) always have 8 electrons. The number of electrons does not fluctuate for neutral oxygen atoms. Eliminate C.
• Option D: Isotopes of an element have the same atomic number (so same number of protons and electrons) but different mass numbers (different number of neutrons). Oxygen - 16 and oxygen - 18 are isotopes of oxygen (atomic number 8), so both have 8 electrons. This is correct.

Answer:

D. The number of electrons are the same for all isotopes of an element - so both oxygen - 16 and oxygen - 18 contain 8 electrons.