How many valence electrons does indium (In) have?

• A. 3
• B. 1
• C. 5
• D. 7

Answer: (A)

Verified step by step guidance

1. Identify the atomic number of indium (In), which is 49, and determine its electron configuration to understand the distribution of electrons in its shells.
2. Write the full electron configuration for indium: \$1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6 4d^{10} 5s^2 5p^1$.
3. Focus on the electrons in the outermost shell (the highest principal quantum number, n=5) because valence electrons are those in the outermost shell.
4. Count the electrons in the 5s and 5p orbitals: \$5s^2\( and \)5p^1$, which together give the total number of valence electrons.
5. Sum these electrons to find the total valence electrons for indium, which explains why the answer is 3.