2. Atomic Structure Worksheet



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  1. The idea that matter is made from tiny indivisible (atomos) particles, was proposed in ancient times in a certain country. Name the country. (2016 OL q4b)



  1. How did John Dalton describe atoms? ( 2010 HL Q4(a))



  1. State two assumptions of Dalton’s atomic theory of 1808. (2010 HL Q5a)



  1. Give two properties of cathode rays. (2011 HL Q4a)



  1. During the 1870s Crookes investigated cathode rays using vacuum tubes like that shown below. (i) Give one way of detecting the presence of cathode rays in a vacuum tube. (ii) Name the scientist who around 1897 identified cathode rays as subatomic particles and, using a vacuum tube, measured their charge-to-mass ratio. What name was given to the subatomic particle he identified? (9) (2015 HL Q5a)



  1. Name the English scientist, pictured on the right, who identified (cathode rays) electrons as negatively charged subatomic particles in the 1890s. (6) (2011 HL Q5b , 2008 HL Q4f, 2007 HL Q4b, 2006 OL Q4f)



  1. Describe the plum-pudding model of the atom proposed by Thomson around 1897. (2016 HL Q4b, 2014 HL Q4b)





  1. The scientist who discovered the atomic nucleus is shown in the photograph on the right. What was his name? (2012 OL Q5e, 2010 OL Q4a, 2004 OL Q4a)



  1. Describe the nature (composition) of an alpha-particle (α-particle). (2005 HL Q4b)





(2007 OL Q5c)

  1. Rutherford concluded around 1910 that the electrons in an atom are located in a large, almost empty space surrounding a tiny, dense, positive nucleus. State three observations made by Rutherford’s team when they bombarded gold foil with alpha-particles. Explain how Rutherford deduced from these observations that the nucleus is (i) positive, (ii) small and dense. (15) (2015 HL Q5b)

  2. In 1909 Rutherford bombarded a very thin sheet of gold foil with alpha particles, most of which passed straight through it undeflected. Some alpha particles, however, were deflected at large angles and a very small number were reflected back along their original paths. The first of these observations was not inconsistent with the ‘plum pudding’ model of the atom that had been proposed by Thomson in 1904, but Rutherford had to formulate a new model of atomic structure to account for the other two observations. (i) What are alpha particles? (4) (ii) Describe the structure of Thomson’s ‘plum pudding’ model of the atom. (6) (iii) Explain why some alpha particles were deflected at large angles as they passed through the gold foil. (6) (iv) Why were some alpha particles reflected back along their original paths? Why did this happen to only a very small number of alpha particles? (6) (v) Draw a labelled diagram to show the new structure of the atom proposed by Rutherford. (3) (2012 HL Q11a)





(2007 HL Q11a)

  1. The scientist pictured on the right used charged oil drops to determine the size of the charge on a sub-atomic particle. Name the scientist, and the sub-atomic particle involved in his experiments. (2009 HL Q4a)



  1. The following names are omitted from the passage below, which outlines the history of the development of our knowledge about atoms. Thomson Rutherford Dalton Moseley Bohr Write in your answer book the name corresponding to each number, 1 to 5. (25)

In ancient Greece, Leucippus and his pupil, Democritus, said that matter is made up of atoms. About two centuries ago 1 described atoms as tiny, indivisible particles. Almost a century later, 2 discovered the electron. A few years after that 3 carried out the experiment, involving the scattering of alpha particles by gold foil, that resulted in the discovery of the nucleus. Later 4 developed a theory restricting electrons in atoms to energy levels. In the early 1900s 5 discovered that the atoms of each element have a characteristic positive nuclear charge now called the atomic number (2013 OL Q10a)





(2012 OL Q10c, similar 2007 OL Q11a)

  1. The electron was the first of the sub-atomic particles to be discovered. It was identified in experiments using cathode rays that were carried out in the late nineteenth century. Name the scientist (i) who, about 1897, measured the ratio of charge to mass of the electron, e/m, (ii)) who, about 1911, measured the charge on the electron, e. (9) (2010 HL Q5b)



  1. Atoms are made up of the subatomic particles protons, neutrons and electrons. Copy the following table into your answer book and fill in the missing information. (21)

(2012 OL Q5b, 2008 OL Q5a, 2004 OL Q10c)

  1. The values of the atomic number and of the mass number for the most abundant isotope of the element hydrogen, H, are both 1. What does this fact tell us about the composition of the H nuclei? Naturally-occurring carbon consists mainly of carbon-12 atoms but it also contains a small percentage of carbon-14 atoms. In terms of their subatomic particles, state two ways in which these carbon atoms are similar, and one way in which they differ. (9) (2012 OL Q5 c,d)



  1. Copy and complete the table. (15)

(2015 OL Q10a)





How many (i) electrons, (ii) neutrons, has the aluminium ion, 27 13Al3+?

(2015 HL Q4a, 2014 OL Q4b, 2003 HL Q4a2011 HL q5a)





  1. In 1913, atomic numbers were introduced by the young English scientist pictured on the right. Two years later he was killed in action at Gallipoli during World War I. Who was he? (6) (2009 OL Q5a)





  1. What contribution did Henry Moseley, the scientist shown in the photograph, make to the systematic arrangement of the elements in the periodic table?

(2008 HL Q4b)

  1. Define (i) atomic number, (ii) relative atomic mass.(iii) mass number (2013 HL Q4b), 2012 hl Q4b, 2004 HL Q4a, 2011 HL Q5a, 2009 OL Q5a , 2006 OL q5a)



  1. Explain why relative atomic masses are rarely whole numbers (2015 HL Q4b, 2013 OL Q5a)



  1. Three of the five fundamental processes that occur in mass spectrometry are detection, acceleration and vaporisation of substance. What are the two other fundamental processes that occur in mass spectrometry? (6)

List all five processes in the order in which they occur. (3A sample of the element gallium is composed of 60.1% gallium–69 and 39.9% gallium–71. Calculate the relative atomic mass of gallium from this information. (7) (2014 HL Q10b)

  1. In 1922, Francis Aston was awarded the Nobel Prize in chemistry for detecting the existence of isotopes using the first mass spectrometer. (i) What are isotopes? (7) (ii) What is the principle of the mass spectrometer? (9) (iii) Calculate, to two decimal places, the relative atomic mass of a sample of neon shown by mass spectrometer to be composed of 90.50% of neon–20 and 9.50% of neon–22. (9) (2009 HL Q10c)



  1. (a) (i) What are isotopes? (4) (ii) Define relative atomic mass, Ar. (6) (iii) What is the principle on which the mass spectrometer is based? (9) (iv) Calculate the relative atomic mass of a sample of lithium, given that a mass spectrometer shows that it consists of 7.4 % of 6 Li and 92.6 % of 7 Li. (6) (HL 2006 Q10a)



  1. On what principle is the analytical technique mass spectrometry based? (2003 HL Q4d)



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