use the periodic table in the tools bar to complete the electron configurations for the following elements…

use the periodic table in the tools bar to complete the electron configurations for the following elements: lithium (li): 1s^a2s^b a = 2 b = 1 complete beryllium (be): 1s^c2s^d c = d = done
Answer
Explanation:
Step1: Determine beryllium's atomic number
Beryllium has atomic number 4.
Step2: Fill electron - shells
Electrons fill the 1s orbital first. The 1s orbital can hold a maximum of 2 electrons. Then, the remaining electrons go to the 2s orbital. Since there are 4 electrons in beryllium, 2 go to 1s and 2 go to 2s. So for the electron - configuration $1s^{C}2s^{D}$, $C = 2$ and $D = 2$.
Answer:
$C = 2$ $D = 2$