In general, you use the Aufbau Principle which indicates the order in which the shells and orbitals are filled. You just have to learn it and then you can determine the electron configuration of the elements.
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.