Answer: The given element is phosphorus.
Explanation:
We are given:
Number of electron in an ion = 18 electrons
Charge on the ion = -3
Atomic number is defined as the number of protons or electrons that are present in a neutral atom.
Atomic number = number of protons = number of electrons
An ion is formed when an atom looses or gains electron.
- When an atom looses electrons, it will form a positive ion known as cation.
- When an atom gains electrons, it will form a negative ion known as anion.
To calculate the atomic number for the given anion, we use the equation:
Number of electrons in a neutral atom = Number of electrons in an ion + charge
Number of electrons in a neutral atom = 18 - 3 = 15
Hence, the given element is phosphorus.
