Lithium (Li) Orbital diagram, Electron configuration, and Valence electrons
Lithium has an atomic number of 3 and belongs to Group 1 also known as the alkali metal group. It is situated in the s-block of the periodic table. Lithium has the symbol Li and it is highly reactive and flammable.
In this article, we will discuss – The Lithium Orbital diagram, Electron configuration, and Valence electrons in detail.
Orbital diagram:- A orbital diagram is simply a pictorial representation of the arrangement of electrons in the orbital of an atom, it shows the electrons in the form of arrows, and also, indicates the spin of electrons.
Electron configuration:- Electron configuration is the arrangement of electrons in atomic orbitals. It shows the electrons in numbers, It doesn’t show the details on the spin of electrons like the orbital diagram.
Valence electrons:- Valence electrons are the simply outermost electron of an atom situated in an outermost shell surrounding an atomic nucleus. They can participate in the formation of chemical bonds.
How to find Electron configuration of Lithium (Li)?
The electron configuration of Lithium can be found using the Aufbau principle.
Aufbau Principle:
The word ‘Aufbau’ in German means ‘building up’.
The Aufbau rule simply gives the order of electrons filling in the orbital of an atom in its ground state.
It states that the orbital with the lowest energy level will be filled first before those with high energy levels. In short, the electrons will be filled in the orbital in order of their increasing energies.
For example, the 1s orbital will be filled first with electrons before the 2s orbital.
Simply understand that there are commonly four different types of subshells – s, p, d, and, f.
These subshells can hold a maximum number of electrons on the basis of a formula, 2(2l + 1) where ‘l’ is the azimuthal quantum number.
Value of ‘l’ for different subshells.
Subshells
Value of ‘l’
Maximum number of electrons, 2(2l + 1)
Number of orbitals in the subshell
s
0
2
1
p
1
6
3
d
2
10
5
f
3
14
7
So, in short, the s subshell can hold a maximum of 2 electrons(1 orbital), the p subshell can hold 6 electrons(3 orbitals), the d subshell can hold 10 electrons(5 orbitals), and the f subshell can hold at most 14 electrons(7 orbitals).
Now, the electron configuration of an atom can be built by filling the electrons in a lower energy subshell first then higher, higher, and higher.
Generally, (n + l) rule is used to predict the energy level of subshells.
n = principle quantum number
l = Azimuthal quantum number
⇒ Lower the value of (n + l) for an subshell, the lower its energy, hence, it will be filled first with electrons.
⇒ For two different subshells having same (n + l) value, then the subshell with lower value of n has lower energy.
So, all these are basics of How filling of electrons will be done in different subshells, obviously, you don’t have so much time for writing electron configuration by using so many rules.
Therefore, we have a diagonal rule for electron filling order in the different subshells using the Aufbau principle.
So, the order in which the orbitals are filled with electrons from lower energy to higher energy is – 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p and so on.
Lithium Electron configuration using the Aufbau Principle
A Lithium atom is a neutral atom that has 3 atomic numbers which imply it has a total of 3 electrons.
As per the Aufbau rule, the electrons will be filled into 1s orbital first then 2s, …so on.
Now, for the electron configuration of Lithium, the first 2 electrons will go in 1s orbital since s subshell can hold a maximum of 2 electrons.
The remaining one electron will go in a 2s orbital.
Therefore, the electron configuration of Lithium will be 1s22s1.
The orbital diagram simply represents the arrangement of electrons in the different orbitals of an atom, it uses an arrow to represent the electrons, every orbital(one box) contains a maximum of 2 electrons.
There are three rules followed for constructing the orbital diagram for an atom.
(1). Aufbau’s principle:- This rule state that the lower energy orbital will be filled before the higher energy orbital, for example – the 1s orbital will fill before the 2s orbital.
(2). Hund’s rule:- This rule state that each orbital of a given subshell should be filled with one electron each before pairing them. That means “Each orbital gets one electron first, before adding the second electron to the orbital”.
(3). Pauli Exclusion Principle:- This rule state that, no two electrons can occupy the same orbital with the same spin. That means “One must be spin up (↑) and one must be spin down (↓)”.
If you understand the above rules then constructing the orbital diagram or orbital notation for Lithium is super easy.
Basics of Orbital diagram:-
There are different types of orbitals – s, p, d, and, f. These orbitals contain a number of boxes that can hold a number of electrons. Let’s see.
Each box will hold a maximum of 2 electrons with opposite spin.
S orbital contains 1 box that can hold a maximum of 2 electrons.
P orbital contains 3 boxes that can hold a maximum of 6 electrons.
D orbital contains 5 boxes that can hold a maximum of 10 electrons.
F orbital contains 7 boxes that can hold a maximum of 14 electrons.
The orbital diagram will also be filled with the same order as described by the Aufbau principle. (1s < 2s < 2p < 3s……and so on.)
We know the electron configuration of Lithium is 1s22s1, now for drawing its orbital diagram, we need to show its electrons in form of an arrow in different boxes using Hund’s and Pauli exclusion rule.
The orbital diagram of Lithium contains 1s orbital, and 2s orbital. 1s orbital contains 1 box, 2s orbital also contains 1 box.
Lithium has a total of 3 electrons and one box can hold up to the two electrons.
Therefore, the first two electrons will go in the 1s orbital, and the remaining one electron will go in the 2s orbital in a clockwise direction (↑).
Lithium Orbital diagram
Electron configuration Vs Orbital diagram for Lithium
The main difference between the orbital diagram and electron configuration is an orbital diagram shows electrons in form of arrows whereas an electron configuration shows electrons in form of numbers. Also, the orbital diagram shows details on the spin of electrons whereas the electron configuration doesn’t show it.
Both these follow the Aufbau principle (Diagonal rule).
Electron configuration for Lithium via Bohr model (Orbit)
Bohr model describes the visual representation of orbiting electrons around the small nucleus. It used different electron shells such as K, L, M, N…so on.
These electron shells hold a specific number of electrons that can be calculated via the 2n2 formula where n represents the shell number.
Electron shells
Shell number (n)
Max. number of electrons (2n2)
K
1
2
L
2
8
M
3
18
N
4
32
So, K is the first shell or orbit that can hold up to 2 electrons, L is the 2nd shell which can hold up to 8 electrons, M is the third shell that can hold up to 18 electrons, and N is the fourth shell that can hold up to 32 electrons.
Now, Lithium has an atomic number of 3 and it contains a total number of 3 electrons. Hence, 2 electrons will go into the first shell(K), and the remaining electron will go into the second shell(L).
Therefore, the electrons per shell for Lithium is 2, 1, hence, we can say, based on the shell, the electronic configuration of the Lithium atom is [2, 1].
Valence electrons are the outermost electrons present in the outermost shell of an atom. They have more energy, hence, they are part of most chemical reactions.
We can find valence electrons of an atom either by knowing its periodic group number or its electron configuration. Both these ways are super easy.
Finding Lithium Valence electrons through the Group number
For neutral atoms, the valence electrons of an atom will be equal to its main periodic group number. However, for transition metals, the process of finding valence electrons is complicated.
Now, for determining the valence electron for the Lithium atom, look at the periodic table and find its Group number. The group number can be found from its column on the periodic table.
So, the number of valence electrons in Lithium is 1. Since it belongs to Group 1st in the Periodic table.
Finding Lithium Valence electrons through the Electron configuration or Bohr model
We know, the electron configuration of the Lithium atom is 1s22s1, and valence electrons are those electrons found in the outer shell of an atom.
This electron configuration of Lithium shows that the outer shell of Lithium has only 1 electron (2s1), hence, the number of the valence electrons in the Lithium atom is 1.
Also, we know, that the electron configuration of Lithium-based on the shells is [2, 1], which means, the two electrons are present in the first shell, and the remaining one electrons are present in 2nd shell or outer shell.
Hence, the electrons found in the 2nd shell of the Lithium atom are its valence electrons because it is the outermost shell also called the valence shell.
The 2nd shell or outer shell of the Lithium atom contains only 1 electron, therefore, the number of valence electrons in the Lithium atom is 1.
What are the Ground state and Excited-state Electron configurations of Lithium?
There is a simple difference between Ground state and Excited-state configuration.
The ground state configuration of an atom is the same as its regular electron configuration in which electrons remain in the lowest possible energy.
So, the ground-state electron configuration for the Lithium atom is 1s22s1.
The excited-state configuration of an atom is different from the regular configuration of an atom, this occurs, when an electron is excited and jumps into a higher orbital.
The excited-state electron configuration for Lithium is 1s22p1.
What is the shorthand electron configuration of Lithium?
The shorthand electron configuration for the Lithium atom is [He] 2s1.
∴ [He] electron configuration is 1s2.
Which element has the 1s22s1 Electron configuration?
Element with electron configuration 1s22s1 is Lithium (Li) which has the atomic number of 3.
How many valence electrons does Lithium have?
The Lithium atom has only 1 valence electron in its outermost or valence shell. Lithium is belonged to group 1st and has the atomic number of 3.
What is the orbital diagram for Lithium (Li)?
The orbital diagram for Lithium is drawn with 2 orbitals. The orbitals are 1s and 2s. The Lithium orbital diagram contains 2 electrons in the 1s orbital and the remaining one electron in the 2s orbital.
The orbital diagram for a ground-state electron configuration of the Lithium atom is as follows –
What is the electron configuration of the Li+ ion?
We know, in general, that the electron configuration of Lithium (Li) is 1s22s1.
Now, in the Li+ ion, the positive charge means, Lithium loses one electron.
Therefore, to write the electron configuration of the Li+ ion, we have to remove one electron from the configuration of Lithium (Li).
∴ The resulting electron configuration for the Lithium-ion (Li+) will be 1s2. It resembles the configuration of the nearest inert gas i.e Helium.
Properties of Lithium
It appears silvery-white in color.
It is one of the lightest metal and solid elements.
It is highly reactive and flammable.
It has a boiling point of 1330 °C and a melting point of 180.50 °C.
It has a body-centered cubic crystal structure.
Summary
The electron configuration of Lithium in terms of the shell or orbit is [2, 1].
The ground-state electron configuration of the Lithium (Li) atom is 1s22s1. And for the excited state, it is 1s22p1.
The shorthand electron configuration for Lithium is [He] 2s1.
The electron configuration for the Li+ is 1s2.
The number of valence electrons available for Lithium atoms is 1. Lithium is situated in Group 1st and has an atomic number of 3.
The first shell of Lithium has 2 electrons and the outer shell or valence shell of Lithium has only 1 electron, hence, the number of valence electrons in the Lithium atom is 1.
The orbital diagram for Lithium is drawn by following three principles – the Aufbau principle, Hund’s principle, and Pauli’s exclusion principle.
The Lithium orbital diagram comprises two orbitals. The two orbitals are 1s and 2s.
The first two electrons will go in the 1s orbital and the remaining one electron in the 2s orbital.
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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