Let's break down the problem step-by-step:
1. Understand what the atomic number tells us:
- The atomic number of an element is the number of protons in the nucleus of an atom of that element.
- For phosphorus (symbol [tex]\( P \)[/tex]), the atomic number is 15. This means that a phosphorus atom has 15 protons.
2. Determine the number of protons in the [tex]\(P^{-3}\)[/tex] ion:
- The number of protons does not change when an atom becomes an ion. It remains the same as its atomic number.
- Therefore, the [tex]\(P^{-3}\)[/tex] ion also has 15 protons.
3. Understand the significance of the [tex]\( -3 \)[/tex] charge:
- The [tex]\( -3 \)[/tex] charge indicates that the ion has three more electrons than a neutral phosphorus atom.
- A neutral phosphorus atom, with an atomic number of 15, has 15 electrons because the number of electrons equals the number of protons in a neutral atom.
4. Determine the number of electrons in the [tex]\(P^{-3}\)[/tex] ion:
- Since the [tex]\(P^{-3}\)[/tex] ion has three additional electrons compared to a neutral phosphorus atom, we add 3 to the 15 electrons in the neutral atom.
- This gives us [tex]\( 15 + 3 = 18 \)[/tex] electrons.
Therefore, a [tex]\(P^{-3}\)[/tex] ion has 15 protons and 18 electrons.
The correct answer is:
- 15 protons and 18 electrons
