Hydrogen is the 1st element in the periodic table and its symbol is ‘H’. The total number of electrons in hydrogen is one. 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 hydrogen 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, period and groups, valency and valence electrons of hydrogen, bond formation, compound formation, and application of different principles.
Hydrogen 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 hydrogen is 1. That is, the number of electrons in hydrogen is 1. Therefore, a hydrogen atom will have one electron in the first shell.
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 hydrogen 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 power 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 s-orbital can have a maximum of two electrons. So, an electron of hydrogen enters the 1s orbital. Therefore, the hydrogen electron configuration will be 1s1.
How to write the orbital diagram for hydrogen?
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 hydrogen(H), you have to do the electron configuration of hydrogen. 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. This is clearly shown in the figure of the orbital diagram of hydrogen.
Determining the period and group of hydrogen
The last orbital of an element is the period of that element. The electron configuration of hydrogen shows that the last orbital of hydrogen is 1. That is, the period of hydrogen is 1.
Again, the total number of electrons in the last orbit of an element is the group of that element. The total number of electrons in the last orbit of hydrogen is one. Therefore, the group number of hydrogen is 1. Therefore, the period and group of hydrogen are both 1.
Determining the valency and valence electrons
If the last orbit of an element has 1,2,3 or 4 electrons, then the number of electrons in the last orbit is the valency of that element. From the hydrogen electron configuration, we can say that an electron exists in the last orbit of hydrogen. Therefore, the valency of hydrogen is 1.
Again, the number of electrons in the last orbit(shell) of an element, the number of those electrons is the valence electrons of that element. In the electron configuration of hydrogen, we see that an electron exists in the last orbit of hydrogen. Therefore, the valence electrons of hydrogen are one. Finally, we can say that the valency and valence electrons of hydrogen are 1.
Determining the block of hydrogen
The elements that have the last electron entering the s orbital after electron configuration are called s-block elements. Again, the elements in group-1 of the periodic table are the s-block elements.
The electron configuration of hydrogen implies that the last electron of hydrogen enters the s-orbital(1s). As we know, hydrogen is an element of group-1 and the last electron of hydrogen enters the s-orbital. So, we can say that hydrogen is the s-block element.
Formation of hydrogen ionic bond
The bond formed by the creation of positive and negative ions is called an ionic bond. During the chemical connection of metal and non-metal atoms, one or more electrons of the last energy level of the metal atom are transferred to the last energy level of the non-metal atom.
The compound that forms ionic bonds is called an ionic compound. Magnesium atoms form ionic compounds with hydrogen. The electron configuration of the magnesium atom shows that there are two electrons in the last orbit of magnesium. The magnesium atom acquires a stable octal structure of near inert gas by releasing two electrons from its last orbit. And magnesium is converted to Mg+2 ions.
On the other hand, an electron exists in the last orbit of the hydrogen atom. The hydrogen atom acquires the structure of helium by accepting an electron. And hydrogen is converted to H– ion. Inversely charged Mg2+ and 2H– ions are combined by attraction to each other to form an MgH2 compound through ionic bonding.
Covalent bonding of hydrogen
The bond formed by the electron shared between two atoms is called a covalent bond. The hydrogen atom combines with the carbon, fluorine, chlorine, oxygen, and silicon atoms to form covalent bonds. And (CH4, HF, HCl, H2O) form compounds.
In the case of H2O: The electron configuration shows that an electron exists in the hydrogen atom. Again, the electron configuration of oxygen shows that there are six electrons in the last orbit of the oxygen atom. Two hydrogen atoms join one oxygen atom to form a covalent bond through electron sharing. And forms H2O compounds through covalent bonds.
In the case of SiH4: The electron configuration of silicon(Si) shows four electrons in the last orbit of a silicon atom. These four electrons in the silicon atom cannot be abandoned or accepted. So, a silicon atom shares four electrons with four hydrogen atoms. Si-H forms single covalent bonds and SiH4 forms compounds.
Properties of hydrogen
- The atomic number of hydrogen is 1.
- The total number of electrons in hydrogen is one.
- The active atomic mass of hydrogen is [1.00784, 1.00811].
- Hydrogen is an s-block element.
- s-block elements react with hydrogen to form hydride compounds.
- The valency of hydrogen is 1.
- Hydrogen compounds are highly alkaline.
- The valency and valence electrons of hydrogen are 1.
- The group and period of hydrogen are both the same.
- Hydrogen forms ionic and covalent bonds.
- The melting point of hydrogen is 13.99 K (−259.16 °C, −434.49 °F) and the boiling point is 20.271 K (−252.879 °C, −423.182 °F).
- The electronegativity of hydrogen is 2.20
Reaction with hydrogen
Hydrogen reaction with group-1 elements
The elements of group-1 are Lithium(Li), sodium(Na), potassium(K), rubidium(Rb), cesium(Cs). Which is known as an alkali metal. Alkali metals react with dry hydrogen at 400°C to form metallic hydride compounds. Li, Na, K, Cs all the elements of group-1 react with hydrogen to form hydride compounds.
2Na (s) + H2 (g) → 2NaH ( Na+ + H– ) (sodium hydride)
2K (s) + H2 (g) → 2KH (potassium hydride)
2Rb (s) + H2 (g) → 2RbH (Rubidium hydride)
2Cs + H2 (g) → 2CsH (cesium hydride)
But in the case of the lithium atom, its temperature is 800 ° C.
2Li + H2 → 2LiH (lithium hydride).
Going from top to bottom(Li to Cs), the activity of the reaction decreases. This is because the cation size increases from the top to the bottom of the group. As a result, the M–H bond is weakened. [Here, M = Li, Na, K, Cs, Rb]
Hydrogen reaction with group-2 elements
Group-2 elements are beryllium(Be), magnesium(Mg), calcium(Ca), strontium(Sr), barium(Ba), and radium(Ra). All the elements except the beryllium element of group-2 react with hydrogen and form hydride compounds.
Mg (s) + H2 → MgH2
Ca (s) + H2 → CaH2
Sr (s) + H2 → SrH2
Reaction of halogen with hydrogen
H2 + F2 → 2HF
H2 + Cl2 → 2HCl
H2 + Br2 → 2HBr
H2 + I2 → 2HI
All the above compounds are soluble in water. The above compounds (H–Cl, H–F, H–Br, H–I) are mixed with water to form an H+ ion. Which combines with water to produce H3O+ ion.
HF + H2O → H3O + + F –
HCl + H2O → H3O + + Cl –
HBr + H2O → H3O + + Br –
HCl + H2O → H3O + + I –
Formation of hydride compounds
Under special conditions, at high pressures and temperatures, the elements of group-15 combine with hydrogen to form hydride compounds. E.g., NH3, PH3, AsH3.
N2 + 3H2 → 2NH3 + heat. (200atm and 500°C)
H2 does not react directly with phosphorus. However, PH3 is produced when white phosphorus is heated together in a solution of caustic soda.
P4 (white) + 3NaOH + 3H2O → PH3 + 3NaH2PO2
P4 (white) + 3KOH + 3H2O → PH3 + 3KH2PO2
The two compounds are Lewis base because of the presence of unpaired electrons in the NH3 and PH3 molecules. The alkalinity of NH3 is higher than that of PH3.
The value of electronegativity of the nitrogen atom in the NH3 molecule is 3.0 but the value of electronegativity of the phosphorus(P) atom in the PH3 atom is 2.1. That is, the Nitrogen(N) atom is more negatively charged than the phosphorus atom.
Therefore, the concentration of electrons in the N–H bond between the NH3 molecules tends to be more toward the nitrogen atom. NH3 compounds are more alkaline than PH3.
Application of hydrogen dual law
The electron configuration shows that an electron of hydrogen exists. The hydrogen atom receives one electron and acquires the electron configuration of helium and becomes more stable by exhibiting the same properties as an inert gas. The two hydrogen atoms form the H2 compound through electron share.
Explanation of hydrogen bonding
Hydrogen bond: When a hydrogen atom combines with a very high electrically negative element to form a covalent compound, the electrons participating in the bond are more attracted to a very high electronegative element.
As a result, polarity is created between them. When such polar molecules come close to each other, the positive hydrogen end is particularly attracted to the negative end of the other molecule and forms a bond through a weak attraction. This weak attraction is called hydrogen bonding.
The hydrogen bond is expressed by the dot (. . .) sign. A hydrogen-bonding strength is about 0.01. For example, Hydrogen bonding is observed in molecules like hydrogen fluoride(HF), water(H2O), ammonia(NH3), ethanoic acid(CH3COOH), and phenol(C6H5OH), etc.
Properties of hydrogen bond
- Hydrogen bonds are weak bonds. Even more so than covalent bonds. Hydrogen bonding strength 8–42 kJ/mol. On the other hand, the covalent bond strength is 200–450kj/mol.
- The strength of the hydrogen bond depends on the value of the electronegativity of the hydrogen atom to the other atom. The higher the value of electronegativity of the connected atom, the higher the hydrogen bonding force. The values of electronegativity of elements F, O, and N are 4.0, 3.5, and 3.0. A sequence of hydrogen bonding energy H — F> H — O> H — N.
- Hydrogen bonds have specific bonding orientations.
- The position of the hydrogen bond depends on the direction of the unpaired electron present in the atom of the electronegative element associated with the hydrogen atom.
- A large number of molecules are joined together by hydrogen bonding. As a result, the molecules remain in a cohesive state.
- The physical position of the molecule changes in hydrogen bonding.
- The size of a hydrogen atom is smaller than the size of an atom of another electronegative element bound by a hydrogen bond. As a result, a strong repulsive force acts between the last orbital electrons of the two atoms.
- In order to minimize the value of repulsion, the positions of hydrogen and electronegativity are linear.
- The effect of hydrogen bonding is to change the melting point, boiling point, solubility, density, viscosity, and the surface texture of the compound.
Prerequisites for Hydrogen Bonding
- The corresponding molecules must have hydrogen atoms.
- The atom attached to the hydrogen atom in the corresponding molecule must be an extremely electronegative element. E.g., O, F, N.
- Molecules must have unpaired electrons.
- The influence of unpaired electrons plays a major role in the formation of hydrogen bonds.
- The bond between the electronegative element and the hydrogen atom must be more polarized.
- The size of the electronegative atom attached to the hydrogen atom must be small. The smaller the size of the atom attached to the hydrogen atom, the more effective the polarization between the positive edge of the hydrogen atom and the negative edge of the electronegative element becomes more effective. The efficiency of hydrogen bonding is also increased. For this reason, Cl, Br, S, and P form compounds with negative elements of hydrogen but do not form hydrogen bonds.
- Must have static electron attraction. This attraction results in the formation of hydrogen bonds.
Types of Hydrogen Bonding
There are two types of hydrogen bonds.
i. Intermolecular hydrogen bonding.
ii. Intramolecular hydrogen bonding.
Intermolecular hydrogen bonding
Hydrogen bonds formed between different molecules of the same or different compounds are called intermolecular hydrogen bonds. Hydrogen bonds are formed between individual molecules of the same or different compounds. E.g. HF, H2O, CH3COOH.
Intramolecular hydrogen bonding
Hydrogen bonding between different parts of the same molecule of the same compound is called intramolecular hydrogen bonding. The formation of hydrogen bonds is called chilation. E.g., C6H4(OH)(NO2), hydroxy-benzaldehyde C6H4(OH)CHO, salicylic acid C6H4(OH)COOH. Intramolecular hydrogen bonds exist between these molecules.
Hydrogen is the first element of the periodic table. The hydrogen element is exceptional compared to the other elements in the periodic table. This article gives an idea about the electron configuration of hydrogen and orbital diagram, period and group, valency and valence electrons, bond formation, compound formation, and application of different principles.
1. How do you write the electron configuration for hydrogen?
Ans: Hydrogen electron configuration is 1s1.
2. What is the electron configuration for the H+ ion?
Ans: Electron configuration for the H+ ion is 1s0.
3. What is the formula of hydrogen ions?
4. How many electrons does H+ have?
Ans: 0 electron.
5. Is H+ just a proton?
Ans: yes. H+ is just a proton.
6. How many valence electrons does hydrogen have?
Ans: One valence electron.
7. How many valence electrons does H+ have?
Ans: Zero valence electron.
- Wiberg, Egon; Wiberg, Nils; Holleman, Arnold Frederick (2001). Inorganic chemistry. Academic Press. p. 240. ISBN 978-0123526519.
- Lide, D. R., ed. (2005). “Magnetic susceptibility of the elements and inorganic compounds”. CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 978-0-8493-0486-6.