Question

oxygen has an atomic number of 8. what can you conclude from this fact?
an atom of oxygen weighs 8 grams.
an atom of oxygen has 4 protons and 4 electrons.
an atom of oxygen has 8 positrons.
an atom of oxygen has 8 protons.

Explanation:

• The atomic number of an element is defined as the number of protons in the nucleus of its atom.
• For oxygen with atomic number 8, this means an oxygen atom has 8 protons.
• The first option is wrong because atomic number is not related to atomic weight in grams like that.
• The second option is wrong as atomic number 8 means 8 protons (and in a neutral atom, 8 electrons, not 4 each).
• The third option is wrong because positrons are not related to atomic number; atomic number is about protons.

Answer:

D. An atom of oxygen has 8 protons.