What Are Node And Nodal Plane, Types Of Node, Important Topics For JEE Chemistry 2025
Shrivastav 14 May, 2024
Share
What Are Node And Nodal Plane : In chemistry, a node refers to a point or region in a molecular orbital where the probability of finding an electron is zero. It arises from the mathematical description of the wave function representing the electron's behavior within the molecule. Nodal planes are surfaces passing through the nucleus where the probability of finding an electron is also zero. These nodes and nodal planes are crucial in understanding molecular orbital theory, as they help visualize the distribution of electron density within molecules, influencing their properties and behaviors.
What Are Node And Nodal Plane : Have you ever heard of nodes in quantum mechanics and wondered what they are all about? Nodes play a crucial role in shaping the behaviour of electrons within atoms, and understanding them is key to unravelling the mysteries of atomic structure. In this article, we'll delve into the concept of nodes, including angular nodes and radial nodes, and their significance. So, let's embark on this fascinating journey together and explore the realm of nodes in simple terms.
Before we delve into the specifics of angular and radial nodes, let's first grasp the concept of nodes in quantum mechanics. In the context of atomic structure, nodes are regions in space where the probability of finding an electron is zero. Think of nodes as "forbidden zones" where electrons are not allowed to exist according to the mathematical equations that describe their behaviour.
What Are Node and Nodal Plane
What Are Node and Nodal Plane: Node represents the region where probability of finding an electron is zero (i.e., Ψ and Ψ 2 = 0) . Similarly nodal plane represents the plane having zero probability of finding electron.
Types Of Node In Chemistry
In chemistry, nodes represent points or regions where the probability of finding an electron in a molecular orbital is zero. There are different types of nodes based on their orientation and location within the molecule:- Nodal planes: These are flat surfaces passing through the nucleus where the probability of finding an electron is zero. Nodal planes are commonly found in molecular orbitals such as σ, π, and δ orbitals.
- Angular nodes: These nodes are formed by angular lobes of orbitals and are present in p and d orbitals. They divide the orbital into distinct lobes with opposite signs.
- Radial nodes: These nodes occur along the radial direction from the nucleus outward. They are present in s, p, and d orbitals and represent regions where the probability of finding an electron is zero along a radial axis.
Radial Node
Radial Node : Radial nodes, also referred to as radial wavefunction nodes, are regions in space where the radial probability distribution function of finding an electron is zero. Unlike angular nodes, which divide space along specific axes, radial nodes divide space radially away from the nucleus. In other words, radial nodes represent spherical shells or layers around the nucleus where electrons cannot be found. Radial nodes are associated with the principal quantum number (n) of an orbital, which determines the size and energy of the orbital. Each value of n corresponds to a different energy level and number of radial nodes.
s Orbitals (n = 1, 2, 3, ...) :-
s orbitals have no radial nodes in the ground state (n = 1), one radial node in the first excited state (n = 2), two radial nodes in the second excited state (n = 3), and so on. The number of radial nodes increases with increasing principal quantum number (n).
p Orbitals (n = 2, 3, 4, ...) :-
p orbitals have no radial nodes in the ground state (n = 2), one radial node in the first excited state (n = 3), two radial nodes in the second excited state (n = 4), and so on. The number of radial nodes increases with increasing principal quantum number (n).
d Orbitals (n = 3, 4, 5, ...) :-
d orbitals have no radial nodes in the ground state (n = 3), one radial node in the first excited state (n = 4), two radial nodes in the second excited state (n = 5), and so on. The number of radial nodes increases with increasing principal quantum number (n).
Formula of Radial Nodes :-
Radial nodes can be calculated using the below-written formula:
Number of Radial nodes = n – l – 1
Where n = principal quantum number, l = Azimuthal quantum number.
Angular Node
Angular nodes, also known as azimuthal nodes, are regions in space where the probability density of finding an electron is zero along a particular axis or direction. In simple terms, angular nodes divide the space around the nucleus into different angular regions where electrons are prohibited from existing.
Angular nodes are associated with the angular momentum quantum number ( l ) of an orbital, which determines the shape and orientation of the orbital. Each value of l corresponds to a different type of orbital shape, with the number of angular nodes equal to l .
s Orbitals ( l = 0) :-
s orbitals have no angular nodes and are spherical in shape. They are characterized by a single lobe or region of high electron probability centred around the nucleus. Since l = 0, there are no angular nodes in s orbitals.
p Orbitals ( l = 1) :-
p orbitals have one angular node and are dumbbell-shaped. The angular node divides the space along the axis of the dumbbell, where the probability density of finding an electron is zero. Since l = 1, p orbitals have one angular node.
d Orbitals ( l = 2) :-
d orbitals have two angular nodes and are characterized by more complex shapes with multiple lobes and nodes. The two angular nodes divide the space into different angular regions where electrons are prohibited from existing. Since l = 2, d orbitals have two angular nodes.
For P x :
P
x
yz plane
P
y
xz plane
P
z
xy plane
Formula of Angular Nodes : The value of the angular nodes is not based on the value of the principal quantum number. It is only based on the value of azimuthal quantum number.
Number of Angular nodes = l
Where l = Azimuthal quantum number
Total Nodes
Total Nodes : The total number of nodes in an orbital is the sum of angular nodes ( l ) and radial nodes (n – l – 1), where n is the principal quantum number. For example, the total number of nodes in an orbital with principal quantum number n = 3 and angular momentum quantum number l = 1 would be 3 (1 angular node + 2 radial nodes).
Total number of nodes = Number of radial nodes + Number of Angular nodes = (n – l – 1) = (n – 1)
Therefore, Total number of nodes = ( n – 1)
Nodes Important Points For Remember
Radial nodes divide space radially away from the nucleus, resulting in concentric spherical shells or layers where electrons cannot be found.
- Radial nodes affect the size and energy of an orbital but do not significantly influence its shape.
- The number of radial nodes increases with increasing principal quantum number (n).
Angular Nodes
- Angular nodes divide space along specific axes, resulting in regions where the probability density of finding an electron is zero along those axes.
- Angular nodes determine the shape and orientation of an orbital, affecting its overall geometry.
- The number of angular nodes depends on the angular momentum quantum number ( l ) and varies with different types of orbitals.
|
Orbital |
Nodal plane |
Orbital |
Nodal Plane |
|
s |
None |
d xy |
XZ & YZ Planes |
|
P x |
YZ Plane |
d yz |
XZ & XY Planes |
|
P y |
XZ Plane |
d xz |
XY & YZ Planes |
|
P z |
XY Plane |
|
Planes perpendicular to XY plane, passing through origin (nucleus) and inclined at 45° to X & Y axis |
|
|
None (two nodal cones are available) |
Node Solved Example
Q.1 : Calculate the total number of angular nodes and radical nodes present in 3p orbital:
Sol : For 3p-orbital, principal quantum number, n = 3 and azimuthal number l = 1
Number of angular nodes = l = 1
Number of radial nodes = n – l – 1 = 3 – 1 – 1 = 1
Summary Of Nodes
- Radial nodes = n – l - 1,
- Angular nodes = l ,
- Total nodes = n – l , where n and l are principal and azimuthal quantum numbers.
e.g., In 3p-orbital, Radial nodes = 3 – l – 1 = 1 (= n – l – 1)
Angular nodes = 1 (= l )
Total nodes = 2 (one radial, one agular)
What Are Node And Nodal Plane FAQs
Q.1 : What factors determine the number of radial nodes and angular nodes in an atomic orbital?
Q.2 : How do radial nodes and angular nodes contribute to the spatial distribution of electrons within atoms?
Q.3 : How do the number of radial nodes and angular nodes vary with different types of orbitals?
Q.4 : What is the significance of radial nodes and angular nodes in understanding atomic structure?
Q.5: Can radial nodes and angular nodes be observed experimentally?
Q.6: How do radial nodes and angular nodes affect the energy levels of electrons within atoms?
Q.7 ; Are radial nodes and angular nodes exclusive to specific types of orbitals?
Q.8: How can I visualize radial nodes and angular nodes in atomic orbitals?
Q.9: What are radial nodes and angular nodes in the context of quantum mechanics?
Q.10 : What is the difference between radial nodes and angular nodes?
Live & recorded classes available at easeDashboard for progress trackingMillions of practice questions at your fingertips
