Question

Provide the four quantum numbers for the outermost electron in Ti3+.

Answer 1

First we need to know the electronic configuration of the element.

The atomic number of Ti is 22 (this information can be found in the periodic table). This means that the atom has 22 protons, so, it must have 22 electrons.

In order to find the electronic configuration we have to put the electrons in different levels until we reach the desired number. In this case we don´t have the Ti element, we have a cation. This Ti atom has lost 3 electrons, that is the reason why it´s charge is +3. So, we have 22-3 electrons, 19 in total. And those are the ones we have to put in levels.

Ti= 1s2 2s2 2p6 3s2 3p6 4s2 3d2

Electrons are always removed from the sub shell with the highest principle quantum number first, so, this means that the 4s electrons are removed first.

Ti+3 = 1s2 2s2 2p6 3s2 3p6 3d1

The "d" orbitals can be imagined as this:

In each box we can put 2 electrons, so in this case we will have:

The "half arrow" represents the electron.

Now the quantum numbers:

"n": indicates the level where the electron is. In this case 3.

"l": indicates de shape of the orbital, 0 is for "s", 1 is for "p" and 2 is for "d". So, l=2.

"m": indicates in which "box" is the electron, in this case is in -2. So, m= -2

"s": is the spin. We have to fill the boxes from left to rigth and fist up and then down. Our electron is up so it is +1/2.

To sum up:

n= 3

l=2

m= -2

s= +1/2