* Atomic number: Sodium (Na) has an atomic number of 11, meaning it has 11 protons and 11 electrons.

* Electron configuration: The electron configuration describes how the electrons are distributed in different energy levels (shells) and subshells:

* 1s² 2s² 2p⁶ 3s¹

Let's break it down:

* 1s²: The first shell (n=1) has a single subshell called 's', which can hold a maximum of 2 electrons. So, sodium has 2 electrons in the 1s subshell.

* 2s²: The second shell (n=2) also has an 's' subshell, which holds 2 electrons.

* 2p⁶: The second shell also has a 'p' subshell, which can hold a maximum of 6 electrons. Sodium has all 6 electrons in this subshell.

* 3s¹: The third shell (n=3) has an 's' subshell, which contains just 1 electron.

In summary: A sodium atom has 2 electrons in its first shell, 8 electrons in its second shell, and 1 electron in its third shell.