Question

activity b: removing and adding electrons
get the gizmo ready:

• choose ionization energy from the drop - down menu.

question: how does the radius of an atom affect the ability of the protons in the nucleus to hold on to and attract electrons?

1. predict: ionization energy (ie) is the energy required to remove an electron from an atom. as atomic radius increases, the valence electrons get farther from the nucleus. how do you think an atoms size will affect its ability to hold on to its valence electrons? why?
2. investigate: select h. in the gizmo, the hydrogen atom is shown next to a positive charge. as you move the atom to the right, the force of attraction between the positive charge and the valence electron will increase until the electron is removed.

slowly drag the atom towards the charge. after the electron is removed, use the ruler to measure the distance between the original and the final position of the electron. record the distance and ionization energy in the table, then repeat for the other group 1 elements.

element

h

li

na

k

rb

cs

fr

|distance (no units)|
|ionization energy (kj/mol)|

Explanation:

As atomic radius increases, the distance between the nucleus and valence - electrons increases. According to Coulomb's law, the electrostatic force of attraction between oppositely - charged particles (protons in the nucleus and valence electrons) is inversely proportional to the square of the distance between them. So, a larger atomic radius weakens the attraction of the nucleus for valence electrons, making it easier to remove an electron (lower ionization energy).

Answer:

As an atom's size (atomic radius) increases, its ability to hold on to its valence electrons decreases because the increased distance between the nucleus and valence electrons weakens the electrostatic force of attraction.