Does the radius of the atom change when an electron is excited?

The radius of the atom increases when the electron in a hydrogen atom undergoes a transition from the 1s-orbital to a 2p-orbital.

How is this possible? Why does exciting an electron to a higher energy state increase the radius of the atom?

• This can be anything from a very short to a very long story, depending on how much you already know. What is a hydrogen atom, to begin with? What is it made of? – Ivan Neretin Jun 18 at 15:54
• Atomic radii are not very well defined. tl;dr: the 'average radius' / most probable distance is larger for a 2p orbital than for the 1s. – Martin - マーチン Jun 18 at 15:54
• If an atom is excited by a large amount of energy to close to its ionisation energy, its size becomes vast compared to that at its lowest energy. In the Bohr model the radius increases as $n^2$ when $n$ is the principle quantum number. Search for Rydberg atoms. – porphyrin Jun 18 at 17:15
• See also Rydberg atoms. E.g for an atom of potassium, and an electron excited to n=600, the electron occurs up to 0.1 mm far from the kernel. – Poutnik Jun 19 at 4:07