Mendelevium is a block f, period 7 actinide element. Its electron configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 4d10 5p6 4f14 5d10 6s2 6p6 5f13 7s2. Another way to write this is [Rn] 5f13 7s2 since the beginning of its configuration is the same as radon's.
[Rn] 7s2 is the noble gas notation for radium. A link is provided to the Wikipedia article on radium.
[Rn]7s2
[Rn] 5f6 7s2.
Lanthanum has an atomic number of 57 and is the first element in the Lanthanoids. Its full orbital notation is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 5d1.
[Rn] 5f6 7s2
[Rn]5f14 7s2 7p1
[Rn] 5f9 7s2
[Rn] 7s2 5f1
The electron configuration of uranium is: [Rn]5f36d17s2.
[Rn] 5f14 7s2
[Rn] 5f14 6d7 7s2