00:01
To determine these electron configurations, we need to know how many electrons are present, which is determined by the z number.
00:07
Z specifically tells us the number of protons, but for a neutral species in ground state, we'll have the same number of electrons.
00:15
Z equals 55 is cesium.
00:19
So, following the off -aw principle, it's 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6 ,000, 4s2 ,000, 3d10, 4 p6, 5s2, 4010, 5p6, 6s1.
00:37
And if we sum up all of these superscripts, they'll equal 55...