Question

can someone help me understand how to write a electron arrangement for elements such as Carbon, helium etc... how do you know how much electrons goes in each level?

Answer 1

Simple. Let's take Carbon. Carbon has an atomic number of six which means it has 6 electrons. Now orbital only gets a certain number of slots; order of orbitals goes as follows: s,p,d,f, etc... but we will focus only on these four.

The s orbital has one slot, the p orbital has three slots, the d orbital has five slots, and the d orbital has nine slots.

Each slots can house a total of two electrons: one spinning up and another spinning down (in order to maintain equilibrium).

Now the more electrons an element has the more orbitals it will need. Back to carbon; having six electrons it will need 3 orbitals: 1s 2s and 2p
To fill them in it would look like this:

Now when inserting electrons you always go from left to write with the positive spin going first, this is due to the earths magnetic field.