How many inner shell electrons does a beryllium (Be) atom have?

• A. 2
• B. 0
• C. 1
• D. 4

Answer: (A)

Verified step by step guidance

1. Recall that the electron configuration of an atom describes the distribution of electrons in its atomic orbitals. For beryllium (Be), which has an atomic number of 4, the electrons fill the orbitals starting from the lowest energy level.
2. Write the electron configuration for beryllium: \$1s^2 2s^2$. This means there are 2 electrons in the 1s orbital (inner shell) and 2 electrons in the 2s orbital (outer shell).
3. Identify the inner shell electrons as those in the completely filled shells closer to the nucleus than the outermost shell. For beryllium, the 1s electrons are the inner shell electrons.
4. Count the number of electrons in the inner shell (1s orbital), which is 2 for beryllium.
5. Conclude that beryllium has 2 inner shell electrons based on its electron configuration.