Lithium is the 3rd element in the periodic table and its symbol is ‘Li’. The total number of electrons in lithium is three. These electrons are arranged according to specific rules of different orbits. The arrangement of electrons in different orbits and orbitals of an atom in a certain order is called electron configuration. The electron configuration of a lithium atom can be done in two ways.
- Electron configuration through orbit (Bohr principle)
- Electron configuration through orbital (Aufbau principle)
Electron configuration through orbitals follows different principles. For example Aufbau principle, Hund’s principle, and Pauli’s exclusion principle. This article gives an idea about the electron configuration and the orbital diagram, period and groups, valency and valence electrons of lithium, and application of the different principles.
Lithium atom electron configuration through orbit
Scientist Niels Bohr was the first to give an idea of the atom’s orbit. He provided a model of the atom in 1913. The complete idea of the orbit is given there. The electrons of the atom revolve around the nucleus in a certain circular path. These circular paths are called orbit(shell). These orbits are expressed by n. [n = 1,2,3,4 . . . The serial number of the orbit]
K is the name of the first orbit, L is the second, M is the third, and N is the name of the fourth orbit. The electron holding capacity of each orbit is 2n2.
|Shell Number (n)||Shell Name||Electrons Holding Capacity (2n2)|
- n = 1 for K orbit.
The electron holding capacity of K orbit is 2n2 = 2 × 12 = 2 electrons.
- For L orbit, n = 2.
The electron holding capacity of the L orbit is 2n2 = 2 × 22 = 8 electrons.
- n=3 for M orbit.
The maximum electron holding capacity in M orbit is 2n2 = 2 × 32 = 18 electrons.
- n=4 for N orbit.
The maximum electron holding capacity in N orbit is 2n2 = 2 × 42 = 32 electrons.
Therefore, the maximum electron holding capacity in the first shell is two, the second shell is eight and the 3rd shell can have a maximum of eighteen electrons. The atomic number is the number of electrons in that element.
The atomic number of lithium is 3. That is, the number of electrons in lithium is 3. Therefore, a lithium atom will have two electrons in the first shell and one in the 2nd shell. Therefore, the order of the number of electrons in each shell of the lithium(Li) atom is 2, 1.
Electrons can be arranged correctly through orbits from elements 1 to 18. The electron configuration of an element with an atomic number greater than 18 cannot be properly determined according to the Bohr atomic model. The electron configuration of all the elements can be done through the orbital diagram.
Electron configuration of lithium atom through orbital
Atomic energy shells are subdivided into sub-energy levels. These sub-energy levels are called also orbital. The most probable region of electron rotation around the nucleus is called the orbital. The sub-energy levels depend on the azimuthal quantum number. It is expressed by ‘l’. The value of ‘l’ is from 0 to (n – 1). The sub-energy levels are known as s, p, d, and f.
|Orbit Number||Value of ‘l’||Number of sub-shells||Number of orbital||Sub-shell name||Electrons holding capacity||Electron configuration|
|3s2 3p6 3d10|
|4s2 4p6 4d10 4f14|
- If n = 1,
(n – 1) = (1–1) = 0
Therefore, the value of ‘l’ is 0. So, the sub-energy level is 1s.
- If n = 2,
(n – 1) = (2–1) = 1.
Therefore, the value of ‘l’ is 0, 1. So, the sub-energy levels are 2s, and 2p.
- If n = 3,
(n – 1) = (3–1) = 2.
Therefore, the value of ‘l’ is 0, 1, 2. So, the sub-energy levels are 3s, 3p, and 3d.
- If n = 4,
(n – 1) = (4–1) = 3
Therefore, the value of ‘l’ is 0, 1, 2, 3. So, the sub-energy levels are 4s, 4p, 4d, and 4f.
- If n = 5,
(n – 1) = (n – 5) = 4.
Therefore, l = 0,1,2,3,4. The number of sub-shells will be 5 but 4s, 4p, 4d, and 4f in these four sub-shells it is possible to arrange the electrons of all the elements of the periodic table.
|Sub-shell name||Name source||Value of ‘l’||Value of ‘m’|
(0 to ± l)
|Number of orbital (2l+1)||Electrons holding capacity|
|p||Principal||1||−1, 0, +1||3||6|
|d||Diffuse||2||−2, −1, 0, +1, +2||5||10|
|f||Fundamental||3||−3, −2, −1, 0, +1, +2, +3||7||14|
The orbital number of the ‘s’ sub-shell is one, three in the ‘p’ sub-shell, five in the ‘d’ sub-shell and seven in the ‘f’ sub-shell. Each orbital can have a maximum of two electrons. The sub-energy level ‘s’ can hold a maximum of two electrons, ‘p’ can hold a maximum of six electrons, ‘d’ can hold a maximum of ten electrons, and ‘f’ can hold a maximum of fourteen electrons.
Aufbau is a German word, which means building up. The main proponents of this principle are scientists Niels Bohr and Pauli. The Aufbau method is to do electron configuration through the sub-energy level. The Aufbau principle is that the electrons present in the atom will first complete the lowest energy orbital and then gradually continue to complete the higher energy orbital.
The energy of an orbital is calculated from the value of the principal quantum number ‘n’ and the azimuthal quantum number ‘l’. The orbital for which the value of (n + l) is lower is the low energy orbital and the electron will enter that orbital first.
|Orbital||Orbit (n)||Azimuthal quantum number (l)||Orbital energy (n + l)|
Here, the energy of 4s orbital is less than that of 3d. So, the electron will enter the 4s orbital first and the electron will enter the 3d orbital when the 4s orbital is full. The method of entering electrons into orbitals through the Aufbau principle is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d.
The first two electrons of lithium enter the 1s orbital. The s-orbital can have a maximum of two electrons. Therefore, the remaining one electron enters the 2s orbital. Therefore, the lithium full electron configuration will be 1s2 2s1.
Note: The short electron configuration of lithium is [He] 2s1.
How to write the orbital diagram for lithium?
To create an orbital diagram of an atom, you first need to know Hund’s principle and Pauli’s exclusion principle. Hund’s principle is that electrons in different orbitals with the same energy would be positioned in such a way that they could be in the unpaired state of maximum number and the spin of the unpaired electrons will be one-way.
And Pauli’s exclusion principle is that the value of four quantum numbers of two electrons in an atom cannot be the same. To write the orbital diagram of lithium(Li), you have to do the electron configuration of lithium. Which has been discussed in detail above.
1s is the closest and lowest energy orbital to the nucleus. Therefore, the electron will first enter the 1s orbital. According to Hund’s principle, the first electron will enter in the clockwise direction and the next electron will enter the 1s orbital in the anti-clockwise direction.
The 1s orbital is now filled with two electrons. So the remaining one electron will enter the 2s orbital in the clockwise direction. This is clearly shown in the figure of the orbital diagram of lithium.
Lithium ion(Li+) electron configuration
After the electron configuration, the last shell of the lithium atom has an electron. In this case, the valence electrons of lithium are one, and also valency is 1. The elements that have 1, 2, or 3 electrons in the last shell donate the electrons in the last shell during bond formation.
Lithium atom donates an electron of the last shell to turn into a lithium ion(Li+). The elements that form bonds by donating electrons are called cation. Lithium leaves an electron and turns into a positive ion. Therefore, lithium is a cation element.
Li – e– → Li+
Here, the electron configuration of lithium ion(Li+) is 1s2. This electron configuration shows that the lithium ion(Li+) acquired the electron configuration of helium and it achieves a stable electron configuration.
Determination of group and period through the electron configuration
The last orbit of an element is the period of that element. The electron configuration shows that the last shell of the lithium is 2. So, the period of the lithium atom is 2.
On the other hand, the number of electrons present in the last orbit of an element is the number of group in that element. An electron exists in the last orbit of the lithium atom. That is, the group number of lithium is 1. Therefore, we can say that the period of the lithium is 2 and the group is 1.
Determining the block of lithium by electron configuration
If the last electron enters the s-orbital after the electron configuration of the element, then that element is called the s-block element. The electron configuration shows that the last electron of lithium enters the s-orbital. Therefore, lithium is the s-block element.
The elements in group-1 and 2 are the s-block elements. And helium is the s-block element. There are 14 s-block elements in the 118 elements of the periodic table.
Lithium is an alkali metal
The elements in group-1 of the periodic table are alkali metals. Lithium is the element of group number 1 of the periodic table. Therefore, lithium is an alkali metal. (Excluding the only hydrogen)
Oxidation and Reduction properties
The element of group-1 is lithium. Which is an intense reducing element. The lithium atom donates an electron of the s-orbital. And the lithium atom forms the electron structure of the helium element.
The reducing intensity of lithium is so high that lithium atoms reduce the hydrogen to form lithium hydride compounds.
2Li + H2 → 2LiH
The ionization potential of the alkali metal decreases as it moves from top to bottom within the group of periodic tables. That is, the reduction capacity continues to increase.
As such, lithium is a weak reducing agent and cesium is a severe reducing agent. But lithium is the most powerful reducing agent among alkali metals. The oxidizing potential of lithium atoms is +3.04.
Properties of Lithium
- The atomic number of lithium is 3. The atomic number of an element is the number of electrons in that element. Therefore, the number of electrons in lithium is three.
- Lithium’s standard atomic weight is 6.941.
- Lithium is an alkali and an intensely negative metal. Its oxides and hydroxides are strong alkalis.
- The value of electronegativity of lithium atoms is comparatively much lower. The value of electronegativity of lithium atoms is 0.98.
- The covalent radius of the lithium atom is 128 ± 7 pm.
- The ionic radius of the lithium atom is 6.0 × 10 –2 nm.
- Lithium atom van der Waals radius 182 pm.
- Ionization energies of lithium atoms E1 = 520 kj/mol, E 2 = 7298 kj/mol, E3 = 11815 kj/mol.
- The oxidation states of lithium atoms are +1.
- The volume of lithium atoms is 13.1cc / mol.
- The melting point of a lithium atom is 180.50 ° C (453.65 K, 356.90 ° F). And the boiling point is 1342 C.
- The period of the lithium element is 2. And the group is 1.
- The number of valency and valence electrons of a lithium atom is 1.
- Lithium forms both covalent and ionic bonds.
- Lithium is a highly electrically positive element. As a result, the lithium atom is stable and produces ions in the solution.
- An electron exists in the last orbit of lithium.
- The atomic radius of a lithium atom is 152 pm.
- Lithium atoms react with hydrogen, oxygen, and halogen to form compounds.
Ionic bond of lithium
Lithium atoms form an ionic bond with fluorine atoms through the exchange of electrons. An electron exists in the last orbit of the lithium atom. The lithium atom wants to be more stable by forming one helium atom by eliminating an electron in the last orbit.
On the other hand, The electron configuration of fluorine atom shows that the seven electrons exist in the last orbit. The fluorine atom wants to be more stable like the neon atom by accepting an electron. The lithium atom donates an electron of its last orbit to the fluorine atom and LiF forms compounds through ionic bonds.
lithium compound formation
Reaction of lithium with halogen
Lithium atoms react with halogen to form halide compounds.
- 2Li + F2 → 2LiF
- 2Li + Cl2 → 2LiCl
- 2Li + Br2 → 2LiBr
- 2Li + I2 → 2LiI
The activity of alkali metals with specific halogens gradually increases from lithium to cesium. That is, Li < Na < K < Rb < Cs. But with the exception of lithium, all other alkali metal halides dissolve very easily in water.
The intense gravitational force between Li+ and F– ion in the crystal reduces the solubility of LiF. Therefore, LiF is less soluble in water. LiCl, LiBr, and LiI are soluble in organic solvents ethanol and propanol.
Reaction of oxygen
4Li (s) + O2 (g) → 2Li2O (lithium oxide)
Heating lithium with excess oxygen produces the compound Li2O2.
2Li + O2 → Li2O2 (lithium peroxide).
Reaction of hydrogen
Alkali metals react with dry hydrogen at a temperature of about 400 ° C to form metallic hydrides. But the lithium atom is different from all other alkali metals. Lithium reacts with hydrogen at a temperature of 800°C to produce lithium hydride.
2Li + H2 → 2 LiH.
The reaction activity decreases as it moves from lithium to cesium element. Metal hydride stability tends to decrease from LiH to CsH.
Lithium reacts with water to produce LiOH.
2Li + 2H2O → 2LiOH + H2
Lithium is oxidized by oxygen in the air to produce alkaline Li2O.
4Li + O2 → 2Li2O
Li2O reacts with water to produce mild alkali LiOH.
Li2O + H2O → 2LiOH
As Li2O is alkaline, it destroys the acidity of HCl and produces salt and water.
Li2O + 2HCl → 2LiCl + H2O
Reaction of lithium with other elements
16 Li + S8 → 8Li2S
12Li + P4 → 4Li3P
The alkali metal lithium reacts with nitrogen(N2) at high temperatures to form nitride compounds.
6Li + N2 → 2Li3N
Exceptional properties of lithium atom
In general, elements of the same group have similarities in physical and chemical properties. The elements of group-1 are alkali metals. The elements are lithium(Li), sodium(Na), potassium(K), rubidium(Rb), cesium(Cs).
But the properties of lithium are different from the properties of all the other elements in this group. The elements in group-1 form ionic bonds in halide compounds. But the halide compounds of the lithium atom have covalent bonds.
For this reason, sodium halide is soluble in water but lithium halide is very slightly soluble in water. LiCl, LiBr, and LiI are soluble in various organic solvents (ethanol, propanol, ether).
Alkali metals react with hydrogen at 400° C to form hydride compounds. But lithium atoms form lithium hydride compounds with hydrogen at a temperature of 800° C.
2Li + H2 (800° C) → 2LiH.
The reasons for the exceptional properties of lithium (Li) are-
- The small size of Li atom and Li+ ion.
- The polarization capacity of Li+ ions is high.
- The zero d orbital is missing at the valence level.
- Lithium is a high ionic potential element.
Due to the exceptional properties of lithium, several distinctions of lithium with other alkali metals have been observed. They are-
- Lithium is less active than alkali metals. Its bright color does not fade easily when it comes in contact with air. In the case of other alkali metals, their bright color fades in contact with air.
- Lithium (Li) reacts with oxygen to form only monoxide (Li2O) compounds. But never forms peroxide (Li2O2) or superoxide (LiO2).
- Lithium is the only alkali metal that reacts with nitrogen (N2) to produce Li3N.
6Li + N2 → 2Li3N.
All other alkali metals do not react with nitrogen (N2).
- When the alkaline metal nitride is heated, it decomposes and metallic nitride and oxygen are produced.
2MNO3 → 2 MNO2 + O2. Here, [M = Na, K, Rb]
- When lithium nitride is heated, it decomposes and produces lithium monoxide (Li2O), NO2, and oxygen (O2).
4LiNO3 (heat) → 2Li2O + 4NO2 + O2
- Hydroxides of alkali metals have a strong base. But lithium hydroxide is a weak base.
- Lithium chloride (LiCl) combines with water to form di-hydrate compounds. But NaCl, KCl, and CsCl never form hydrate compounds.
Electron configuration of lithium and the orbital diagram are the main topics of this article. Also, period and group determination, valency and valence electrons, various reactions and compound formation of lithium, and bond formation of lithium have been discussed.
- How do you write the electron configuration for lithium?
Ans: Lithium electron configuration is 1s2 2s1.
- How many electrons are there in lithium?
Ans: 3 electrons.
- What are the three electrons of lithium?
- What is the atomic mass of lithium?
Ans: Lithium standard atomic mass is 6.941
- How many shells does lithium have?
Ans: 2 shells.
- How many valence electrons does lithium(Li) have?
Ans: The valence electron of lithium is one.