2.1 part d

[Kayla Ikemiya 1E]

How do we know that the radius of the atom increases as an electron goes from n=1 to n=2? Is it because the electron is moving further away from the nucleus?

[Harrison Wang 1H]

Yes, the electron moves from a lower energy state to a higher energy state, which is a greater distance from the nucleus. In this case, it moves from the first shell to the second shell.

[Janice Xiao 1I]

The radius also increases because the atomic number/number of protons increases, so the number of electrons increases as well.

[Jessica Nunez 1I]

Does this mean that there is a direct relationship between the number of electrons and the size of the radius?

[Peri Bingham 1G]

Yes and no. It depends on how you are looking at the periodic table. If you go down the periodic table, then yes, there is a direct relationship. As the value of n increases, the radius and the number of electrons both increase because there addition of a new shell, because of the addition of electrons, increases the radius. If you go across the period table, then no, there is an inverse relationship. As you move across, the charge of the nucleus increases so that even with the addition of more electrons, the nucleus is pulling the electrons closer which reduces the size of the radius of the atom.