The point around the nucleus where the electron probability is zero is called a

• A. Cloud
• B. Node
• C. Orbital
• D. Axis

Answer: (B)

In atomic theory, the electron’s position is described by a wavefunction, and the probability of finding the electron is given by the square of that wavefunction. A node is a location where the wavefunction goes to zero, so the probability of finding the electron there is zero. These zeros can occur at specific distances from the nucleus (radial nodes) or along certain directions (angular nodes), but the overarching idea is that a node marks zero probability. A cloud describes where the electron is likely to be found (not zero probability), an orbital is the region defined by the wavefunction for a given state (again not a single zero), and an axis is just a line in space and has no direct relation to probability densities.