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Atomic orbitals are the three-dimensional spaces around the nucleus where the probability of finding an electron is greatest. Atomic orbitals combine to form molecular orbitals.
Have you ever wondered about the different shapes that atomic orbitals can take?
- Quantum mechanics describes various atomic orbital shapes, including s, p, d, and f sub-shells.
- These orbitals exist in different shapes and sizes.
- The specific shapes and sizes of these orbitals can be determined by calculations involving the wave square of the wave function.
| Table of Content |
Key Terms: Principle quantum number, Azimuthal quantum number, Atomic orbitals, Subshell, Wave function, Electrons, Spin quantum number
What are Atomic Orbitals?
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Atomic orbitals are mathematical functions that provide information about the wave nature of electrons (or pairs of electrons) that exist around atomic nuclei.
We use atomic orbitals in quantum mechanics and atomic theory, but what exactly are they?
- These orbitals define regions around the nucleus where we're most likely to find an electron.
- The mathematical form of the atomic orbital predicts the presence of an electron in such a region.
Characteristics of Atomic Orbitals
The characteristics of each atomic orbital are determined by specific properties, known as quantum numbers. We will explore these numbers to understand how they influence the orbitals.
The different quantum numbers are given as
- Principle quantum number (n)
- Azimuthal quantum number or orbital angular momentum quantum number (I)
- Magnetic quantum number (ml)
Each atomic orbital can only hold a maximum of two electrons.
- In completely occupied atomic orbitals each electron has an equal and opposite spin to the other.
- The value of the spin quantum number, denoted by the symbol 'ms' provides insight into the electron spin.
Thus, by determining the values of the four quantum numbers that describe an electron, one can gain insight into any electron residing in any atomic orbital in a given atom. These four quantum numbers are the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the electron spin quantum number.
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| Related Links | ||
|---|---|---|
| Structure of Atom | Quantum Mechanical Model of Atom | Atomic Mass Of Elements |
| How to Find Atomic Mass | Shapes of Atomic Orbitals | Energy level Diagram |
Relationship Between Atomic Orbitals and Quantum Numbers
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The name of the atomic orbital is usually a combination of the principal quantum number (n) and the azimuthal quantum number (l). The atomic orbitals' simple names and the corresponding value of the azimuthal quantum number are listed below.
| Orbital name | Azimuthal quantum number |
|---|---|
| s | 0 |
| p | 1 |
| d | 2 |
| f | 3 |
| g | 4 |
| h | 5 |
The atomic orbitals can be named alphabetically, with the letter 'j' omitted (this is done as some languages do not distinguish between the letters 'j' and 'i'.) As a result,
- When l = 6, the orbital name is denoted as j, and
- When l =7, the orbital name is denoted as k.
The names of the first four orbitals (s, p, d, and f) are derived from the initial descriptions provided by spectroscopists who studied the spectroscopic lines of alkali metals and described them as sharp, principal, diffuse, and fundamental.
- s-subshell can hold 2 electrons
- p-subshell can hold 6 electrons
- d-subshell can hold 10 electrons, and
- f-subshell can hold 14 electrons.
The value of the principal quantum number should be added as a prefix to the alphabetical type of the azimuthal quantum number to name a specific atomic orbital. The value of the azimuthal quantum number is determined by the value of the principal quantum number.
For any given value of 'n,' the value of 'l' can range between zero to (n-1). For example, if 'n' equals 3, the possible values of 'l', which range from zero to (3 – 1), are 0, 1, and 2.
These atomic orbitals will be designated as
- 3s, for n = 3 and l = 0
- 3p, for n = 3 and l = 1
- 3d, for n = 3 and l = 2
It should also be noted that the 3f orbital cannot exist because the values of 'n' and 'l' must both be equal to 3, which is not possible because the value of the azimuthal quantum number must always be lower than the value of the principal quantum number.
Table of All Possible Atomic Orbitals
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Let's take a look at the table of all possible atomic orbitals! This table shows us what happens when the principal quantum number (n) takes on values from 0 to 5.
| Value of the Principal Quantum Number (n) | Possible Values of the Azimuthal Quantum Number (l) | Names of all the Possible Atomic Orbitals for the Given Value of ‘n’ |
|---|---|---|
| 1 | l = 0 (s orbital) | 1s orbital |
| 2 | l = 0 (s orbital) l = 1 (p orbital) | 2s orbital 2p orbital |
| 3 | l = 0 (s orbital) l = 1 (p orbital) l = 2 (d orbital) | 3s orbital 3p orbital 3d orbital |
| 4 | l = 0 (s orbital) l = 1 (p orbital) l = 2 (d orbital) l = 3 (f orbital) | 4s orbital 4p orbital 4d orbital 4f orbital |
| 5 | l = 0 (s orbital) l = 1 (p orbital) l = 2 (d orbital) l = 3 (f orbital) l = 4 (g orbital) | 5s orbital 5p orbital 5d orbital 5f orbital 5g orbital |
Also Read:
| Chapter Related Links | ||
|---|---|---|
| Subatomic Particles of an Atom | Atomic Radii | Diatomic |
| Dalton’s atomic theory | Atomic Radius | Atomic Mass Formula |
Things to Remember
- An atomic orbital is a mathematical function stating the location and wave-like behavior of an atomic electron.
- It is the physical space or region around an atom's nucleus where the probability of a specific electron being present is greatest.
- The name of atomic orbital is a combination of the principal quantum number (n) and the azimuthal quantum number (l).
- There are four types of orbitals: s, p, d, and f (sharp, principal, diffuse, and fundamental).
- The 's-subshell' can hold 2, 'p-subshell' can hold 6, 'd-subshell' can hold 10, and 'f-subshell' can hold 14 electrons.
Sample Questions
Ques. How many types of atomic orbitals are there? (1 Mark)
Ans. There are four types of atomic orbitals (sharp, theory, diffuse, and fundamental) with s, p, d, and f. Within each shell of an atom, there are only a few orbital variations.
Ques. What is called orbital? (2 Marks)
Ans. In atomic theory, an orbital is a mathematical function describing the probability of finding an electron in a specific region around the nucleus. s orbitals, the most basic type, can hold a maximum of two electrons. Other orbital types (p, d, f) have different maximum capacities.
Ques. Why is the s orbital spherical? (2 Marks)
Ans. All s orbitals are spherically shaped and have spherical symmetry. That is, the wave's function will be determined solely by its distance from the nucleus and not by its direction. As the central quantum number of an orbital decreases for any particle, the size of the orbital decreases, but the geometry remains spherical.
Ques. How many electrons are in each s, p, d, and f orbitals? (2 Marks)
Ans. The 's' subshell can hold 2 electrons, the 'p' subshell can hold a maximum of 6, the 'd' subshell can hold a maximum of 10, and the 'f' subshell can hold a maximum of 14 electrons.
Ques. How do orbitals work? (3 Marks)
Ans. Atomic orbitals are the positions surrounding an atom's nucleus where electrons are most likely to be at any given time. It is a mathematical property defining the wave-like characteristics of one electron or a pair of electrons involved in an atom. Electrons occupy low-energy orbitals (closer to the nucleus) until they enter higher-energy orbitals. If there is a choice of equal-energy orbitals, they fill the orbitals as independently as possible. This filling of orbitals alone is referred to as Hund's law when applicable.
Ques. The letter 'n' denotes which quantum number? (1 Mark)
Ans. It denotes 'Principal'.
Ques. Which orbital is dumbbell-shaped? (1 Mark)
Ans. 'p' orbital is dumbbell-shaped.
Ques. What is the atomic orbital theory? (2 Marks)
Ans. An atomic orbital is a mathematical term used in atomic theory and quantum mechanics to explain an electron's position and wavelike behavior within an atom. Each orbital will be occupied by a maximum of two electrons, each with their unique spin quantum number s.
Ques. What is the range of Azimuthal Quantum Number, l? (1 Mark)
Ans. The range of the azimuthal quantum number is 0 to (n – 1), where n is the principle quantum number.
Ques. The quantum numbers +1/2 and −1/2 for an electron represent two quantum mechanical spin states that have no classical analog. Explain this statement. (3 Marks)
Ans. The statement indicates that electron spin quantum states +1/2 and -1/2 exist. Spin quantum number is a conserved characteristic. The spin of an electron is characterized by these two states: +1/2 and -1/2. It is a word used exclusively in quantum physics to describe an electron's characteristics, and it has no basis in classical physics. As a result, the term "no classical analog" is used.
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