Potassium (K) and Krypton (Kr) are in the same period, so they have the same number of electron shells. Potassium is more reactive than Krypton because it only has one valence electron.
K and Kr are both in Period 4, so they each have the n = 1, 2, 3, and 4 shells. Kr is less reactive than K because it already has a complete octet.
“Potassium (K) and Krypton (Kr) are in the same period, so they have the same number of electron shells. Krypton is more reactive than Potassium because it has a full outer shell” is <em>incorrect </em>because having a full outer shell means that the element is unreactive.
“Potassium (K) and Krypton (Kr) are in the same group, so they have the same number of valence electrons. They have different numbers of electron shells” is <em>incorrect </em>for three reasons:
1. K is in Group 1 and Kr is in Group 18.
2. K has one valence electron, and Kr has eight valence electrons.
3. They have the same number of electron shells.
“Potassium (K) and Krypton (Kr) are in the same group, so they have the same number of valence electrons. They have different numbers of electron shells” is <em>incorrect</em> for two reasons:
1. K and Kr have different numbers of valence electrons.
2. They have the same number of electron shells.
