Question

Determine what elements are denoted by the following electron configurations:

Answer 1

Answer:

Electron Configurations - Solutions

Note: The electron configurations in this worksheet assume that lanthanum (La)

is the first element in the 4f block and that actinium (Ac) is the first element in the

5f block. If your periodic table doesn’t agree with this, your answers for elements

near the f-orbitals may be slightly different.

1) sodium 1s2

2s2

2p6

3s1

2) iron 1s2

2s2

2p6

3s2

3p6

4s2

3d6

3) bromine 1s2

2s2

2p6

3s2

3p6

4s2

3d104p5

4) barium 1s2

2s2

2p6

3s2

3p6

4s2

3d104p6

5s2

4d105p6

6s2

5) neptunium 1s2

2s2

2p6

3s2

3p6

4s2

3d104p6

5s2

4d105p6

6s2

4f145d106p6

7s2

5f5

6) cobalt [Ar] 4s2

3d7

7) silver [Kr] 5s2

4d9

8) tellurium [Kr] 5s2

4d105p4

9) radium [Rn] 7s2

10) lawrencium [Rn] 7s2

5f146d1

11) 1s2

2s2

2p6

3s2

3p4

sulfur

12) 1s2

2s2

2p6

3s2

3p6

4s2

3d104p6

5s1

rubidium

13) [Kr] 5s2

4d105p3

antimony

14) [Xe] 6s2

4f145d6

osmium

15) [Rn] 7s2

5f11 einsteinium

16) 1s2

2s2

2p6

3s2

3p6

4s2

4d104p5 not valid (take a look at “4d”)

17) 1s2

2s2

2p6

3s3

3d5

not valid (3p comes after 3s)

18) [Ra] 7s2

5f8

not valid (radium isn’t a noble gas)

19) [Kr] 5s2

4d105p5 valid

20) [Xe] not valid (an element can’t be its own electron configuration)