Final answer:
The correct electron configuration notation for sodium (Na) is 1s2 2s2 2p6 3s1, indicating it has one valence electron.
Step-by-step explanation:
The electron configuration notation for sodium (Na) is 1s22s22p63s1. In this notation, the first two electrons fill the 1s subshell, followed by two more electrons in the 2s subshell. The 2p subshell is then completely filled by six electrons. Lastly, the remaining one electron occupies the 3s subshell, which is the outermost shell in this case. Therefore, the correct notation for the electron configuration of sodium is represented by option B) 1s22s22p63s1. This configuration indicates that sodium has one valence electron outside of the noble gas core that corresponds to neon (Ne).