Write the characteristics of $s$ orbitals.

(N/A) For all $s$-orbitals,the azimuthal quantum number $l = 0$ and the magnetic quantum number $m_{l} = 0$,while the principal quantum number $n$ can take values $1, 2, 3, \ldots$. For example,$1s, 2s, 3s, \ldots$ represent different $s$-orbitals where $n$ varies but $l$ and $m_{l}$ remain zero.
All $s$-orbitals are spherically symmetric,meaning the probability of finding an electron at a given distance from the nucleus is equal in all directions.
The size of the $s$-orbital increases with an increase in the value of $n$. The order of size is: $1s < 2s < 3s < 4s$.
As $n$ increases,the distance from the nucleus increases,leading to an increase in energy and a decrease in the electrostatic attraction between the nucleus and the electron. Consequently,the electron becomes easier to remove.
The number of nodal surfaces (or radial nodes) is given by $(n - 1)$.

Orbital	$1s, 2s, 3s, 4s, 5s, 6s$
No. of nodal surfaces	$0, 1, 2, 3, 4, 5$

$A$ region where the probability density $|\Psi|^{2}$ is zero is called a nodal surface.