Question 1
Which of the following is true about gaining and losing electrons in cobalt?
- The last orbital that gains electrons in cobalt is
and the first orbital that loses electrons in cobalt is
- The last orbital that gains electrons in cobalt is
and the first orbital that loses electrons in cobalt is
- In cobalt,
is the last orbital that gains electrons and the first orbital that loses electrons
- In cobalt,
is the last orbital that gains electrons and the first orbital that loses electrons
Explanation: Cobalt is a transition metal; therefore, it is found in the D block of the periodic table. A ground state cobalt atom has an electron configuration of 
. The last orbitals that gain or lose electrons must be either the 
or 
orbitals, since these are the orbitals with highest energy and located farthest from the nucleus.
Recall that electrons are filled from orbitals of low energy to high energy. A 
orbital has a lower energy than a 
orbital. This means that when you are filling electrons, the last orbital you fill is the 
orbital. When you are assigning electrons to each orbital you assign two electrons to the 
orbital and then the remaining seven electrons to the five 
orbitals; therefore, 
orbitals are filled last when gaining electrons.
When an element loses electrons, the first orbital that loses electrons is the outermost orbital. This occurs because the attractive force of the nucleus on the electron will be weakest in the outermost orbital (because it is farthest away from nucleus); therefore, it will be easy to pull the electron away from the nucleus. In cobalt, the outermost orbital is the orbital (because it has the highest shell number). This means that electrons will be lost from the orbital before the orbital.
. The last orbitals that gain or lose electrons must be either the or orbitals, since these are the orbitals with highest energy and located farthest from the nucleus.
Recall that electrons are filled from orbitals of low energy to high energy. A orbital has a lower energy than a orbital. This means that when you are filling electrons, the last orbital you fill is the orbital. When you are assigning electrons to each orbital you assign two electrons to the orbital and then the remaining seven electrons to the five orbitals; therefore, orbitals are filled last when gaining electrons.
When an element loses electrons, the first orbital that loses electrons is the outermost orbital. This occurs because the attractive force of the nucleus on the electron will be weakest in the outermost orbital (because it is farthest away from nucleus); therefore, it will be easy to pull the electron away from the nucleus. In cobalt, the outermost orbital is the orbital (because it has the highest shell number). This means that electrons will be lost from the orbital before the orbital.
