The total number of nodes of an orbital is the sum of angular and radial nodes and is given in terms of the n and l quantum number by the following equation. Number of nodes=n−l−1 for 3s-orbital, n = 3 l = 0 Nodes = 3 – 0 – 1 = 2 Because for s-orbitals, l = 0, therefore, there is no angular nodes only radial nodes are present, that is, 2 radial nodes.