Nomen: ____________________________________________________

Unit 1: Atomic Structure Problem Set

NOTE: Problem sets are always due the day before the unit exam. 5 points of extra credit is available for the first person to submit a completed problem set if that problem set is mostly accurate and can be used as an answer key with minimal changes.

1. Give the number of protons, neutrons and electrons in the following atoms:Uranium-238 75

33As Bromine-81ProtonsNeutronsElectrons

(Total 3 marks)2. Give the number of protons, neutrons and electrons in the following atoms:

Calcium-40,Charge = +2

12753I-1 140

58Ce+3

ProtonsNeutronsElectrons

(Total 3 marks)3. Which of the following species contain more electrons than neutrons? Show work!

A 21H

B 115B

C 168O2−

D 199F−

(Total 1 mark)4. Which of the following gives the correct composition of the 71Ga+ ion present in the

mass spectrometer when gallium is analyzed.

(Total 1 mark)

5. Use the Periodic Table to find the percentage abundance of neon-20, assuming that neon has only one other isotope, neon-22.

(Total 2 marks)6. Magnesium has three stable isotopes – 24Mg, 25Mg, and 26Mg. The lightest isotope

has an abundance of 78.90%. Calculate the percentage abundance of the other isotopes. Show all work.

(Total 2 marks)7. Chromium has four naturally occurring isotopes, and their names, masses and

relative abundance are given below.Isotope Natural Abundance (%)50Cr 4.3552Cr 83.7953Cr 9.5054Cr 2.36Calculate the relative atomic mass of chromium to the correct number of significant digits. Show all work.

(Total 2 marks)8. Rubium has a relative atomic mass of 85.47 and consists of two naturally occurring

isotopes, 85Rb (u=84.91) and 87Rb (u= 86.91). Calculate the percentage composition of these isotopes in a naturally occurring sample of rubidium. Show all work.

(Total 2 marks)

9. (a) Explain why the relative atomic mass of argon is greater than the relative atomic mass of potassium, even though the atomic number of potassium is greater than the atomic number of argon. ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(b) Deduce the numbers of protons and electrons in the K+ ion.......................................................................................................................................(c) Deduce the electron arrangement for the K+ ion.......................................................................................................................................

(Total 3 marks)

10. Identify a radioactive isotope of carbon and state one of its uses.

(Total 1 mark)

11. (a) List the following types of electromagnetic radiation in order of increasing wavelength (shortest first).

I. Yellow lightII. Red lightIII. Infrared radiationIV. Ultraviolet radiation

(b) Distinguish between a continuous spectrum and a line spectrum.

(c) The thinning of the ozone layer increases the amount of UV-B radiation that reaches the Earth’s surface.

Type of Radiation Wavelength / nm

UV-A 320–380

UV-B 290–320Based on the information in the table above explain why UV-B rays are more dangerous than UV-A.

(Total 5 marks)

12. In the emission spectrum of hydrogen, which electronic transition would produce a line in the visible region of the electromagnetic spectrum? Show all work.

A. n = 2 →n = 1B. n = 3 → n = 2C. n = 2 → n = 3D. n = ∞ → n = 1

(Total 1 mark)

13. Which describes the visible emission spectrum of hydrogen? Show all workA. A series of lines converging at longer wavelengthB. A series of regularly spaced linesC. A series of lines converging at lower energyD. A series of lines converging at higher frequency

(Total 1 mark)

14. Identify which of the following provide evidence to support the Bohr model of the hydrogen atom?

I The energy of the lines in the emission spectra of atomic hydrogen.II The energy of the missing lines in the absorption spectra of helium as seen from the sun.III The relative intensity of the different spectral lines in the emission spectrum of atomic hydrogen.A. I only B. B II only

C. C I and II D. D I and III

(Total 1 mark)

15. What is the electron configuration of vanadium?A. 1s22s22p63s23p63d24s3

B. 1s22s22p63s23p63d34s2

C. 1s22s22p63s23p63d44s1

D. 1s22s22p63s23p63d5

(Total 1 mark)

16. State two ways in which the Schrodinger model of the hydrogen atom differs from that of the Bohr model.

(Total 2 marks)

17. What is the order of increasing energy of the orbitals within a single energy level?

A. d < s < f < pB. s < p < d < fC. p < s < f < dD. f < d < p < s

(Total 1 mark)

18. An ion has the electron configuration 1s2 2s2 2p6 3s2 3p6 3d10. Which ion could it be?

A. Ni2+

B. Cu+

C. Cu2+

D. Co3+

(Total 1 mark)

19. State the full ground-state electron configuration of the following ions.

(a) O2–

(b) Cl–

(c) Ti3+

(d) Cu2+

(Total 4 marks)

20. a. State the full electron configuration of Neon.

b. State the formulas of two oppositely charges ions that have the same electron configurations as Neon

(Total 3 marks)

21. Explain, using electron orbital diagrams to show their electron configurations, why gold and silver are particularly stable. Explain any exceptions to the Aufbau Principal.

(Total 4 marks)

22. Explain, using electron orbital diagrams, why the two most common ions for Iron (Fe) are +2 and +3.

(Total 4 marks)

23. Values for the successive ionization energies for an unknown element are given in the table below.

First ionization energy / kJ mol–1

Second ionization energy / kJ mol–1

Third ionization energy / kJ mol–1

Fourth ionization energy / kJ mol–1

420 3600 4400 5900In which group of the periodic table would the unknown element be found?

A. 1B. 2C. 3D. 4

(Total 1 mark)

24. The first ionization energies of the Period 3 elements Na to Ar are given in Section 8 of the IB data booklet .

a. Explain the general increase in ionization energy across the period.

b. Explain why the first ionization energy of magnesium is greater than that of aluminium.

c. Explain why the first ionization energy of sulfur is less than that of phosphorus.

(Total 3 marks)

25. Identify the sub-level which does not exist.A. 5d B. 4d C. 3f D. 2p

(Total 1 mark)

26. Which is the correct order of orbital filling according to the Aufbau Principle? A. 4s 4p 4d 4f B. 4p 4d 5s 4f C. 4s 3d 4p 5s D. 4d 4f 5s 5p

(Total 1 mark)

27. State the full ground-state electron configuration of the following elements.A. V B. K C. Se D. Sr

(Total 1 mark)

28. Determine the total number of electrons in d orbitals in a single iodine atom.A. 5 B. 10 C. 15 D. 20

(Total 1 mark)

29. Explain why a potassium atom contains an electron in a 4s orbital with no electrons in a 3d orbital whereas a copper(I) ion, Cu+ has the electronic configuration [Ar]3d10 with no electrons in the 4s orbital.

(Total 2 marks)

30. Identify the excited state (i.e. not a ground state) in the following electron configurations.

A. [Ne] 3s23p3 B. [Ne] 3s23p34s1 C. [Ne] 3s23p64s1

D. [Ne] 3s23p63d14s2

(Total 1 mark)

31. Deduce the number of unpaired electrons present in the ground state of a titanium atom.

(Total 1 mark)32. State the ground-state electron configuration of the Fe3+ ion.

(Total 1 mark)33. State the electron configuration of the following transition metal ions by filling in

the boxes below. Use arrows to represent the electron spin.

(Total 4 marks)34. Only a few atoms of element 109, meitnerium, have ever been made. Isolation of an

observable quantity of the element has never been achieved, and may well never be. This is because meitnerium decays very rapidly.(a) Suggest the electron configuration of the ground-state atom of the element.

(b) There is no g block in the Periodic Table as no elements with outer electrons in g orbitals exist in nature or have been made artificially. Suggest a minimum atomic number for such an element.

(Total 4 marks)

35. State the full electron configuration of U2+.

36. Consider how the shape of the Periodic Table is related to the three-dimensional world we live in.(a) How many 3p and 3d orbitals would there be if there were only the x and y dimensions?

(b) How many groups in the p and d block would there be in such a two-dimensional world?

37. The electron configuration of chromium can be expressed as [Ar]4sx3dy.

(i) Explain what the square brackets around argon, [Ar], represent.

(ii) State the values of x and y.x: ..................................................................................................................................y: ..................................................................................................................................

(iii) Annotate the diagram below showing the 4s and 3d orbitals for a chromium atom using an arrow, and , to represent a spinning electron.

4s 3d(Total 3 marks)

38. The electron configuration of chromium can be expresses as [Ar]4sx3dy. (a) Explain what the square brackets around argon, [Ar], represent. (1)

(b) State the values of x and y. (1)

(c) Annotate the diagram below showing the 4s and 3d orbitals for a chromium atom using an arrow up and down to represent a spinning electron.

(Total 6 marks)39. The graph below represents the energy needed to remove nine electrons, one at a 

time, from an atom of an element. Not all of the electrons have been removed.

Which element could this be and why?

a. Cb. Sic. Pd. S

(Total 2 marks)

40. The graph below represents the successive ionization energies of sodium. The vertical axis plots log (ionization energy) instead of ionization energy to allow the data to be represented without using an unreasonably long vertical axis.

State the full electron configuration of sodium and explain how the successive ionization energy data for sodium are related to its electron configuration.

(Total 3 marks)