As it has two postively charged protons in it (along with two neutrons), a Helium nucleus has two electrons 'orbiting' around it. Knowing this, we need to find which orbits they are in.
The lowest energy orbital in an atom is made up of a single 'S' orbital (the 's' describes its shape - spherical) with a principal quantum number of 1 (which indicates the size of the orbital, 1 being the smallest). This is therefore denoted 1s . This orbital can accept two electrons, so both of the helium electrons go into it. The way to express this as a electron configuration is 1s2 , the superscript '2' indicating the number of electrons in the orbital.
Feel free to stop at that point. To be a bit more technical, when we write 1s2 the '1s' is actually a mathematical wavefunction, and the superscript '2' is there because there are two electrons whose wavefunction is 1s, and so we multiply those wavefunctions together - hence the configuration actually means 1s-squared.
Hydrogen electron configuration will be 1s1.
The electron configuration for germanium is [Ar]3d10.4s2.4p2.
The electron configuration of zirconium is: [Kr]5s24d2
Al3+
The complete electron configuration of mendelevium is:1s22s22p63s23p63d104s24p64d104f145s25p65d105f136s26p67s2
The electron configuration for oxygen is [He]2s2.2p4.The electron configuration for sulfur is [Ne]3s2.3p4.
A cation has a depleted electron configuration.
The electron configuration for beryllium, Be, is 1s22s2.
The electronic configuration of einsteinium is: [Rn]5f11.7s2.
The electron configuration of francium is [Rn]7s1.
Hydrogen electron configuration will be 1s1.
Uranium electron configuration: [Rn]5f36d17s2
The electron configuration of beryllium is 1s2 2s2.
The electron configuration of boron is [He]2s2.2p1.
The electron configuration for germanium is [Ar]3d10.4s2.4p2.
The electron configuration for V3 is Ar 3d2.
The electron configuration of V3 is Ar 3d2.