15. When chromium loses two electrons, its configuration changes to
A. [Ar]4s1.
B. [Ar]3d4.
C. [Ar]4s13d5.
D. [Ar]4s13d4.
I'm guessing it's B but I just want to double check
You are correct.
Which of the following is not true in regard to atomic radii of main group elements?
A. Atomic radii decrease in size when the pull of electrons toward the nucleus of an atom is greater.
B. Atomic radii generally increase as you move from left to right across a period.
C. Atomic radii size is related to the number of electrons in the valence level and the number of protons in the nucleus.
D. Atomic radii generally increase as you move down a group.
To determine the configuration of an element after losing electrons, we need to know the electron configuration of the element before losing electrons.
The electron configuration of chromium (Cr) before losing electrons is [Ar]3d54s1.
Chromium (Cr) has 24 electrons, distributed as follows:
1s2 2s2 2p6 3s2 3p6 4s1 3d5
When chromium loses two electrons, it loses them from the 4s orbital, which is the outermost shell.
Therefore, the final configuration of chromium after losing two electrons becomes [Ar]3d4.
So, your initial guess is correct, the answer is B.