Question

Electron configuration of chromium

Answer 1

s-blocks consists of 2 grps.. Grp 1(s^1) & 2(s^2)
p-block consists of metals,metalloids n non-metals
Grp 13 n Grp 18
d-block consists of 3 series of metals..each series has 10 elements wth electronic configuration
f-block consist of 2 series of metals known as lanthanides n actinides
@Somy

Answer 2

okay

Answer 3

so u understood about S block right?

Answer 4

yup

Answer 5

nice
P block
as we said its gr 3-8

Answer 6

what happens is that before actually going to P block
S block has to be filled first

Answer 7

S block takes up to 2 electrons and P block takes up to 6 electrons

Answer 8

if we take Mg as an example

Answer 9

its atomic number is 12 so it's 12th element of periodic table

Answer 10

ok

Answer 11

so how many electrons does it have in total?

Answer 12

12

Answer 13

cool
as you said in total Mg has 12 electrons
now the question is Where are they?

Answer 14

lets start looking at each element before Mg

Answer 15

period 1
first element is H

Answer 16

ok..

Answer 17

so H is in group 1 right?

Answer 18

ys

Answer 19

what block is group 1

Answer 20

s-block
is it 1s^1

Answer 21

thats right
so S block is filled with 1 electron only

Answer 22

now its He

Answer 23

it has in total 2 electrons

Answer 24

both in the same shell
and as we said the one's first to fill up would be S block

Answer 25

this number 1 in 1s^ shows that its shell 1
so if He has 2 electrons in total, both will be in S block right?

Answer 26

but He is in Grp 18..shld be p-block
It's a noble gas

Answer 27

yeah but its same shell
first to fill up is always S orbital

Answer 28

okay

Answer 29

okay so first period has 2 elements thus 2 electrons

Answer 30

both electrons will go to S orbital

Answer 31

thus its 1s^2

Answer 32

next moving down to next period
period 2 has 8 elements
thus 8 electrons

Answer 33

again first filling will be S orbital thus
first 2 electrons (from gr 1 and gr 2) will go to S orbital
so now it'll be
1s^2, 2s^2

Answer 34

get it so far?

Answer 35

yes

Answer 36

cool
after S orbital is filled
we start filling P orbital

Answer 37

so as u reach 3rd element/electron in period 3
your S orbital gets 2, but 1 is left, where is it?

Answer 38

it starts going to P orbital
so now P orbital takes that 1 electron
thus now the configuration looks like this
1s^2, 2s^2 2P^1

Answer 39

r u catching up?

Answer 40

ys

Answer 41

okay so next is 4th electron

Answer 42

it again goes to P orbital so now p orbital has 2 electrons
so
1s^2, 2s^1 2p^2

Answer 43

ok

Answer 44

next its 5th and 6th and 7th and 8th electrons

Answer 45

all go to p orbital

Answer 46

now it becomes like this
1s^2, 2s^2 2P^6

Answer 47

right?

Answer 48

yes

Answer 49

so by the end of period 2 P orbital is filled

Answer 50

because it can take up to 6 electrons and it got it

Answer 51

okay so by this period 2 is done

Answer 52

now we go down to next period
period 3

Answer 53

that means there will be a new shell right?

Answer 54

yes

Answer 55

so as the new shell starts we have to start with subshells meaning S and P orbitals right?
and the first one to start filling will be S orbital

Answer 56

so period 3 group 1
meaning 1 electron in its last shell - shell 3

Answer 57

that 1 electron will go to S orbital

Answer 58

right?

Answer 59

ys

Answer 60

so can u tell how is the electronic configuration for Na going to look like?

Answer 61

2.8.1
1s^1 2s^2 2p^6 3s^1

Answer 62

as u should be getting now is that
we consider the electrons before reaching the last shell
Na has in total 11 electrons, and as we know 1 of this electrons is going to be in last shell s orbital, what about other 10 electrons?
thus u've gotta show the whole configuration
and YAY good job :)

Answer 63

if the question asks u for Last shell configuration only
u can say 3s^1
because as long as u show 3 that means the element is in period 3
and s^1 shows that the element is in S block meaning it has 1 electron in its last shell
thus No doubt that its Na

Answer 64

okay

Answer 65

now i see u r getting it quite well
now can u tell show configuration of Mg on ur own?

Answer 66

lmao show*

Answer 67

2.8.2
1s^2 2s^2 2^6 3s^2

Answer 68

goooooood :) now do it for Ar

Answer 69

2.8.8
1s^2 2s^2 2p^6 3s^2 3p^6

Answer 70

now for Ca

Answer 71

2.8.8.2
1s^2 2s^2 2p^6 3s^2 2p^6 4s^2
I'm nt sure

Answer 72

thats right!!

Answer 73

next the pain stars

Answer 74

and its D block

Answer 75

wait

Answer 76

yeah?

Answer 77

so, 4s comes before 3d

Answer 78

exactly

Answer 79

thats because energy level of 4s is relatively lower then of 3d

Answer 80

because it's nearer to the nucleus
gt it!

Answer 81

thats why now as u reach D block of transition elements S and P orbitals basically freezes thats why no electron will go to P orbital of 4p
and next set of electrons will go to d orbital

Answer 82

it will not YET go there because
D orbital can take up to 10 electrons

Answer 83

once it gets all 10 electrons, we can go to 4P orbital then

Answer 84

okay so everything works as i taught u just now for S and P orbitals filling

Answer 85

can u try writing electronic configuration of V ?

Answer 86

2.8.8.5
I don't know

Answer 87

okay look

Answer 88

look at first transition element
its Sc right?

Answer 89

yes

Answer 90

so what was electronic configuration for the element before this transition one
meaning of Ca

Answer 91

2.8.8.2
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2

Answer 92

good so what we said is that now we start filling 3d orbital and we don't touch other orbitals till it gets all its 10 electrons right?

Answer 93

Sc, first transition element
so its last electron will go to 3d shell thus it'll be 3d^1
do u agree?

Answer 94

why 3d^1 , why shld be 1

Answer 95

because Sc is actually in group 3
and that means 2 of electrons is taken by S orbital

Answer 96

since d orbital of transition element is pretty greedy
thats why it doesn't let P orbital to take the left out 1 electron
and so d orbital takes it to itself

Answer 97

okay

Answer 98

and it keeps on doing it till it gets all 10 electrons to itself