The number of electrons in an ion with 20 protons and an ionic charge of 2+ is
A) 24.
B) 22.
C) 20.
D) 18.
Б) 16
The correct answer and explanation is :
The correct answer is B) 18.
Explanation:
The number of protons in an atom or ion determines its element, and this number is equal to the atomic number of the element. In this case, the element with 20 protons is Calcium (Ca), as its atomic number is 20.
Now, let’s break down how the number of electrons is affected by the ionic charge:
- In a neutral atom, the number of electrons equals the number of protons. So, for a neutral calcium atom (Ca), which has 20 protons, there would also be 20 electrons.
- When an atom becomes an ion, it either gains or loses electrons depending on the charge. The ionic charge tells us whether the atom has lost or gained electrons:
- A positive charge (cation) means the atom has lost electrons.
- A negative charge (anion) means the atom has gained electrons.
In this case, the ion has a 2+ charge. This means the atom has lost 2 electrons. To calculate the number of electrons in this ion:
- Start with the neutral atom’s electron count (20 electrons for neutral calcium).
- Subtract the number of electrons lost due to the 2+ charge:
20 electrons − 2 electrons = 18 electrons.
Thus, the ion has 18 electrons.
Summary:
- The element is calcium (Ca) with 20 protons.
- A 2+ charge means the ion has lost 2 electrons.
- Therefore, the number of electrons in this ion is 18.
This result aligns with option D) 18.