Hydrogen Electron Configuration and Orbital Diagram Diagram

Hydrogen is the 1st element in the periodic table and the symbol is ‘H’. The atomic number of hydrogen is 1, which means its atom has only one electron. So, this one electron enters the 1s orbital. Therefore, the electron configuration of hydrogen is 1s¹.

The electron configuration of hydrogen refers to the arrangement of electrons in the hydrogen atom’s orbitals. It describes how electrons are distributed among the various atomic orbitals and energy levels, and provides a detailed map of where each electron is likely to be found.

To understand the mechanism of hydrogen electron configuration, you need to understand two things. These are orbits and orbitals. Also, you can arrange electrons in those two ways. In this article, I have discussed all the points necessary to understand the mechanism of hydrogen electron configuration. I hope this will be helpful in your study.

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Electron Arrangement for Hydrogen through Bohr Model

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.

Electron configuration of hydrogen through orbital

Atomic energy shells are subdivided into sub-energy levels. These sub-energy levels are also called 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 subshells	Number of orbitals	Subshell name	Electrons holding capacity	Electron configuration
1	0	1	1	1s	2	1s2
2	0 1	2	1 3	2s 2p	2 6	2s2 2p6
3	0 1 2	3	1 3 5	3s 3p 3d	2 6 10	3s2 3p6 3d10
4	0 1 2 3	4	1 3 5 7	4s 4p 4d 4f	2 6 10 14	4s2 4p6 4d10 4f14

Explanation:

• 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 subshells 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 2(2l+1)
s	Sharp	0	0	1	2
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-subshell is one, three in the p-subshell, five in the d-subshell, and seven in the f-subshell. 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)
3d	3	2	5
4s	4	0	4

Here, the energy of 4s orbital is less than that of 3d. So, the electron will enter the 4s orbital first and enter the 3d orbital when the 4s orbital is full. Following the Aufbau principle, the sequence of entry of electrons into orbitals is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p.

Therefore, the complete electron configuration for hydrogen should be written as 1s¹.

How to draw the orbital diagram of hydrogen

The orbital diagram of hydrogen is a graphical representation of the electron configuration of hydrogen atom. This diagram shows how the electrons in the hydrogen atom are arranged in different orbitals and indicates the spin of electrons. Orbital is the region of space around the nucleus of an atom where electrons are found.

To draw an orbital diagram of any atom, you first need to know the atomic orbitals and the orbital notation for that atom, which is already discussed in above. Also you need to know the Hund’s and Paul exclusion principle. These rules explain how electrons occupy orbitals, including why hydrogen’s single electron resides alone in the 1s orbital. Below, we define each principle and apply it to hydrogen.

Hund’s Rule

Hund’s Rule states that when electrons fill orbitals of the same energy (called degenerate orbitals, like the three 2p orbitals), they spread out to occupy each orbital singly before pairing up. Additionally, these single electrons have the same spin (e.g., all spin-up, ↑) to minimize electron-electron repulsion and maximize stability.

• Why It Matters: This rule ensures electrons arrange in a way that lowers the atom’s energy, making it more stable.

Pauli Exclusion Principle

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers. In practice, this means each orbital can hold a maximum of two electrons, and these electrons must have opposite spins (e.g., one ↑ and one ↓).

• Why It Matters: This principle ensures electrons have unique identities within an atom, preventing overcrowding in orbitals and maintaining atomic structure.

Orbital diagrams are usually represented by boxes. Each box represents an orbital and the arrows within the box represent the position of the electron. The boxes are arranged in order of energy of the orbitals. The lowest energy orbitals are closest to the nucleus and the higher energy orbitals are progressively further away from the nucleus in order of their energy levels.

The 1s orbital is the closest and lowest energy orbital to the nucleus. Therefore, the electrons will first enter the 1s orbital. According to Hund’s principle, the first electron will enter 1s orbital in the clockwise direction. This is clearly shown in the figure of the orbital diagram of hydrogen.

Why This Matters for Hydrogen

• Reactivity: Hund’s Rule highlights hydrogen’s unpaired electron, explaining its tendency to form covalent bonds (e.g., H₂, H₂O) or ionic bonds (e.g., NaH) to gain stability.
• Atomic Structure: The Pauli Exclusion Principle ensures hydrogen’s electron has a unique quantum state, laying the foundation for understanding more complex atoms.
• Learning Tip: For students, these rules are key to mastering electron configurations and orbital diagrams for all elements, starting with simple atoms like 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.

Determine the valency and valence electrons of hydrogen

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.

Determine block of hydrogen through electron configuration

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. 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

The elements in group 17 are halogens. The halogen elements are fluorine(F), chlorine(Cl), bromine(Br), iodine(I), and astatine(At). Each halogen atom reacts with hydrogen and forms compounds.

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 bases 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.

References

1. Callen, E. (1955). Configuration interaction applied to the hydrogen molecule. The Journal of Chemical Physics, 23(2), 360-362.
2. Perrot, F. (1994). Hydrogen-hydrogen interaction in an electron gas. Journal of Physics: Condensed Matter, 6(2), 431.