## ground state electron configurations

halle young 4A
Posts: 68
Joined: Thu Jul 11, 2019 12:16 am

### ground state electron configurations

can someone please explain this problem? i didn't really understand any part of it

2A.11 Which M3+ ions (where M is a metal) are predicted to have the following ground state election configurations: (a) [Ar] 3d6; (b) [Ar] 3d5; (c) [Kr] 4d5; (d) [Kr] 4d3

thanks

AnvitaaAnandkumar_1B
Posts: 56
Joined: Fri Aug 02, 2019 12:15 am

### Re: ground state electron configurations

I think this question can be solved by looking at a periodic table.

(a) [Ar] 3d6 :
No. of electrons in M ^+3 state = 18 + 6 = 24
Therefore no. of electrons in M = 24 + 3 = 27
Therefore M is Co

(b) [Ar] 3d5 :
No. of electrons in M^+3 state = 18 + 5 = 23
Therefore no. of electrons in M = 23 + 3 = 26
Therefore M is Fe

(c) [Kr] 4d5 :
No. of electrons in M^+3 state = 36 + 5 = 41
No. of electrons in M = 41 + 3 = 44
Therefore M is Ru

(d) [Kr] 4d3 :No. of electrons in M^+3 state = 36 + 3 = 39
No. of electrons in M = 39 + 3 = 42
Therefore M is Mo

SarahCoufal_1k
Posts: 61
Joined: Thu Jul 25, 2019 12:17 am

### Re: ground state electron configurations

If it is in a plus 3 state, shouldn't we subtract 3 electrons instead of add?

005162520
Posts: 60
Joined: Tue Sep 24, 2019 12:17 am

### Re: ground state electron configurations

I’m also confused as to why we add instead of subtracting 3.