If an electron has 8 electrons in its ground state, what is the correct electron configuration for the element?
When building the electron configuration of an atom from scratch, you need to use
- The Aufbau Principle, which states that electrons will occupy available lower-energy orbitals before moving up to higher-energy orbitals
- Hund's Rule, which states that electrons will first be placed in unoccupied degenerate orbitals, then pair up to fill these degenerate orbitals
- Pauli's Exclusion Principle, which states that electrons that occupy the same orbital must have opposite spins
So, an energy diagram for empty orbitals looks like this
According to the Aufbau Principle, electrons will occupy energy levels in increasing order of energy.
The first energy level, which is lowest in energy, will thus be occupied first. This energy level contains the 1s-orbital.
Since an orbital can hold a maximum of two electrons, the first two electron will be placed in the 1s-orbital. The electron configuration for this atom starts out like this
#"X: " 1s^2#
You've used up
Next, the second energy level, which contains a total of four orbitals
- one s-orbital
- three p-orbitals
Since the 2s-orbital is lower in energy than the 2p-orbitals, this orbital will be filled first. The electron configuration for your atom will now be
#"X: " 1s^2 2s^2#
You're down to
Now, these three electrons will be placed in the 2p-orbitals. The complete electron configuration for
#"X: " 1s^2 2s^2 2p^4#
To get a visual of how these last
This means that each 2p-orbital will get one electron. After you distribute
As you know, a neutral atom has equal numbers of protons in its nucleus and electrons surrounding its nucleus. This means that element
Notice the placement of the