Give the number of core electrons for Cd
A) 48
B) 44
C) 46
D) 47
E) 45
The correct answer and explanation is :
The correct answer is B) 44 core electrons.
Explanation:
To determine the number of core electrons in cadmium (Cd, atomic number 48), follow these steps:
Step 1: Identify the Atomic Number
Cadmium has an atomic number of 48, meaning it has 48 total electrons in its neutral state.
Step 2: Write the Electron Configuration
The full electron configuration of cadmium (Cd) is:
[
1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6 4d^{10} 5s^2
]
Alternatively, using noble gas notation:
[
[\text{Kr}] 4d^{10} 5s^2
]
Step 3: Identify Core and Valence Electrons
- Core electrons: These are the electrons in all inner shells, excluding the outermost shell.
- Valence electrons: These are the electrons in the outermost shell that participate in bonding.
For cadmium:
- The outermost shell is n = 5, which contains 5s² electrons.
- All other electrons (from n = 1, 2, 3, 4) are core electrons.
Step 4: Count the Core Electrons
- Total electrons = 48
- Valence electrons = 2 (from 5s²)
- Core electrons = 48 – 2 = 44
Thus, cadmium has 44 core electrons.
Conclusion
The correct answer is B) 44 core electrons. This is because only the two 5s electrons are considered valence electrons, while all others are part of the inner, core shells.
Here is an educational diagram illustrating the electron configuration of cadmium (Cd), highlighting the core electrons (44) and valence electrons (2).