Answer: Boron (B) has 2 energy levels.
Explanation: Energy levels, also known as electron shells, are regions around an atomic nucleus where electrons are found. Boron, with an atomic number of 5, has an electron configuration of 1s2 2s2 2p1.
In this configuration, the first energy level (shell) is fully occupied with 2 electrons in the 1s subshell, and the second energy level contains the remaining 3 electrons in the 2s and 2p subshell.
Significance: Understanding the number of energy levels in boron helps describe its electronic structure and its reactivity in chemical reactions.
The arrangement of electrons in different energy levels contributes to its properties as an element.