Electronic Structure

1.1 ATOMIC STRUCTURE
Electronic Structure
Section A
For each of the questions only one of the lettered responses (A-D) is correct.

Select the correct response in each case and mark its code letter by connecting the dots as illustrated on the answer sheet.

1. Which one of the following represents the electronic arrangement of the outer shell of the chlorine atom (atomic number, 17)?


3s


3p

A

­¯

­¯
­¯
­
B

­

­¯
­¯
­¯
C

­¯

­
­
­
D

­

­¯
­
­

2. Which one of the following is the electronic configuration of the bromine atom?
A 1s22s22p63s23p63d104s14p6
B 1s22s22p63s23p63d104s24p7
C 1s22s22p63s23p63d104s24p5
D 1s22s22p63s23p63d104s24p6

3. To which one of the following energy levels (denoted by n) does the electron in a hydrogen atom return when the emission spectrum is in the ultraviolet region;
A n= 1
B n = 2
C n = 3
D n = 4

4. Which one of the following does not represent the electronic configuration of an atom in its ground state?
A 1s2 2s2 2p3
B 1s2 2s2 2p4
C 1s2 2s2 2p6 3s1
D 1s2 2s2 2p6 3d1



5. Which one of the following is the maximum number of atomic orbitals having a principal quantum number of two?
A 2
B 4
C 8
D 9

6. Which one of the following contains no unpaired electrons in the ground state?
A Be
B N
C Si
D F

7. Which one of the following is the electronic structure of a metal with a maximum oxidation state of +3?
A 1s2 2s2 2p6 3s1
B 1s2 2s2 2p6 3s2 3p1
C 1s2 2s2 2p6 3s2 3p6 3d10 4s2
D 1s2 2s2 2p6 3s2 3p4

8. Which one of the following statements regarding electronic orbitals is correct?
A Each p-orbital can hold a maximum of six electrons.
B The 3p-orbitals have a higher energy level than the 3s-orbital.
C The three 3p-orbitals have slightly different energy levels.
D The 1s-orbital has the same size and shape as the 2s-orbital.

9. The number of electrons in the 3d orbital of the atom of atomic number 23 is
A 2
B 3
C 4
D 5






10. Which one of the following correctly represents the electronic structure of the named atom in its ground state?
A B C D
2p

2s

1s




2p

2s

1s



2p



2p

2s

1s










2s











1s


Lithium
Boron Carbon Nitrogen

11. The vanadium atom (atomic number 23) in its ground state has the electronic configuration:
A 1s2 2s2 2p6 3s2 3p6 3d3 4s2
B 1s2 2s2 2p6 3s2 3p6 3d2 4s3
C 1s2 2s2 2p6 3s2 3p6 3d1 4s2 4p2
D 1s2 2s2 2p6 3s2 3p6 3d2 4s2 4p1

12. Which one of the following does not have the electronic structure
1s2 2s2 2p6 3s2 3p6 3d10 4s24p6?
A Kr
B S2-
C Se2-
D Sr2+

13. The graph below shows the first ionisation energies for a series of elements whose atomic numbers increase in sequence. Which one could represent nitrogen?



D
1st ionisation C
energy
B
A

atomic number


14. Which one of the following is the electronic configuration of a titanium atom?
A 1s22s22p63s23p64s24p2
@B 1s22s22p63s23p63d24s2
C 1s22s22p63s23p63d'4s'
D 1s22s22p63s23p'4s'4p'

15. Which one of the following compounds contains two ions with different electronic configurations?
A CaCl2
B MgF2
C MgO
D NaCl

16. Which graph represents a plot of energy, E, against principal quantum number (energy level), n, for an electron in a hydrogen atom?






17. Which one of the following atoms contains no unpaired electrons in its ground state?
A Beryllium
B Boron
C Carbon
D Lithium

18. Which one of the following sub-shells does not exist?
A 2p
B 2d
C 3p
D 4d

19. Which one of the following represents the electronic structure of the chloride ion in its ground state?

20. Which one of the following represents the shape of a p-orbital?B
















Section B

1. An outline of the periodic table is shown below.
(a) Indicate on it the positions of the s block, p block and d block elements. [2]





s P d





(b) Write the electronic configuration for
(i) a potassium atom
1s22s22p63s23p64s1
(ii) a sulphur atom
1s22s22p63s23p4 [2]

(c) Write the empirical formula for potassium sulphide indicating the charges on the ions.
K+2S2- [1]


2.
(a) Write the electronic configuration of an iron atom in the ground state
K+2S2- [1]

(b) Explain the term ground state.
K+2S2-
K+2S2-
K+2S2- [1]

3. The diagram below shows the first four energy levels in a sodium atom. Label these levels and, using arrows to represent electrons, show the electronic structure of sodium in the ground state.








[3]


4. Beryllium occurs to a small extent in the earth's crust. It is a steel-grey metal, which is extremely light. Beryllium is used for "windows" in X-ray apparatus because it has the lowest stopping power per unit mass thickness of all suitable construction materials.
Calculate the energy of X-rays of frequency 3 x 1017 Hz passing through a "beryllium window".
K+2S2-
K+2S2-
K+2S2- [2]

5. The Periodic Table is divided into s, p and d blocks. Using the symbols s, p and d complete the table below.
element
block
beryllium

manganese

phosphorus

[2]