Question

3. The third electron in lithium 7 3Li is attracted by an effective charge of approximately +1e so the Bohr model can be used. (Note that this is because the two innermost electrons are very close to the nucleus with Z = 3 and so the net charge is +3 + -2e = +1e.)

3A.Give the four quantum numbers of the third electron in the ground state of lithium and give the name of the subshell in standard notation

3.B Calculate the energy of the three lowest energy levels. Draw an energy level diagram. (Don’t forget what state the outermost electron starts in.)

Answer 1

Lithium has atomic number of 3 . This means it has 3 elecron 3 proton and 3 neutron

Now , we know by BOHR model that electron are filled in shells K,L,M....

So each shell can hold is 2n²

SO now K can hold 2*1=2 electrons

hence third electron will be filled in M shell

a) SO the configuration of third electron (n,l,m,n)

n=2

l =n-1 = 1

m=-1,0,1

s=+/-1/2

b)

lithium energy levels

outermost electron starts in infinite state /shell.In the diagram we have the energy of three lowest energy levels

In bohr model energy of a level is given by -13.6*Z²/n² (where z=atomic number and n is shell number)