1. 1 The following interactive exercises and accompanying assessment quiz was devised by Evelyn M. Sabino, Ph.D Using diagrams obtained from www.saburchill.com This work was performed under a Texas Higher Education Coordinating Board Course Redesign Grant Principal Investigator David A. Carter, Ph.D

2. Keep a periodic table handy. Please down load the file and work on it at your own computer. On the following slides you will be presented with a number of diagrams of atomic species. Always in solving the requested puzzle consider the number and arrangement of electrons in each diagram and also nuclear structure. Follow the instructions in the box. When you are finished click in the text box on the slide, clear it, and then type in explanations for what you have done. When finished look at the sample answer file. All outlined boxes are instructions to students. Non outlined boxes are information for instructors. 2

3. The following exercise uses simple representations of the elements such as the three diagrams to the left. Please examine them. The central blue ball represents the nucleus. You will recall from your Learning Exercise that the nucleus contains the protons (different for each element) and neutrons. Here the protons are represented by a number and an upper case P, the neutrons by a number and an uppercase N. Differing from the presentation in the Learning Exercise the electrons here are represented by a small red ball with a white lower case e superimposed on the ball. The representation of electrons is in shells, represented by concentric circles, out from the nucleus. It can not be emphasized enough that this is an extremely simplified picture of the actual arrangement of electrons in an atom. In this exercise concentrate your attention on the number of electrons and their placement in shells. 3

4. Consider the arrangement of electrons as well as the nuclear structure. All the diagrams on this page have several similar characteristics and at the same time illustrate trends. Remember you are primarily concentrating on the electrons. Click and drag the diagrams. Arrange them so that you illustrate the trends. Type Answers Below Questions. What are the similarities you noted among members of this group? Enter where there is a space. All have odd number of protons and number of protons and electrons are equal. All have one proton in the outer shell. What are the trends you observed? Number of shells increases with number of protons. If examining only inner shells, 1 st shell always has 2 electrons and second has 8 in the two biggest atoms. Be specific and detailed in your answers 4 H Li Na Rb

5. Consider the preceding slide. Consult the periodic table. Go back and label each diagram with its atomic symbol or name. Did you observe any connections between the arrangement of the periodic table and your arrangement? Write you answer in this box and below this line. All atoms were in group one. I sorted them with small on left and large on right. Periodic table has them sorted with small on top and large on the bottom. 6

6. 7 Consider the arrangement of electrons as well as the nuclear structure. All the diagrams on this page have several similar characteristics and at the same time illustrate trends. Remember you are primarily concentrating on the electrons. Click and drag the diagrams. Arrange them so that you illustrate the trends. Type Answers Below Questions. What are the similarities you noted among members of this group? All have an even number of protons and number of electrons equal number of protons. Except for the smallest, all of them have 8 electrons in outer shell. So far no atom has had more than 2 electrons in the 1 st shell. Considering only inner shells, shell 1 always has 2 electrons, shell 2 always has 8 electrons and shell 3 always has 18 electrons. What are the trends you observed? For the most part, there are more electrons in the other shells. They are sorted from smaller to larger which corresponds both to the number of shells and the number of electrons. Be specific and detailed in your answers He Ne Kr Xe Ar

7. 8 Consider the preceding slide. Consult the periodic table. Go back and label each diagram with its atomic symbol or name. Did you observe any connections between the arrangement of the periodic table and your arrangement? Write you answer in this box and below this line. All of these elements are in period 18 (8A), the noble gasses. Where I sorted them with small on the left to large on the right, the periodic table has them sorted from top to bottom.

8. These diagrams show a trend. Focus primarily on the electrons. Click and drag the diagrams to arrange them to show the trend. Type Answers Below Questions. What are the similarities you noted among members of this group? All of atoms have the same number of protons and electrons. All of them have electrons in two and only two shells. All atoms have 2 electrons in the 1 st shell. What is the trend and what similarities do you see among the members of this group? The number of electrons increases in the 2 nd shell from 1 to 8 (which is the most we saw in the 2 nd in shell in all of the diagrams we have viewed so far). They are organized by increasing number of electrons. 9 Li Be B C N O F Ne

9. 10 These diagrams show a trend. Focus primarily on the electrons. Click and drag the diagrams to arrange them to show the trend. Type Answers Below Questions. What are the similarities you noted among members of this group? All of atoms have the same number of protons and electrons. All of them have electrons in three and only three shells. All atoms have 2 electrons in the 1 st shell and 8 electrons in the 2 nd shell. What is the trend and what similarities do you see among the members of this group? The number of electrons increases in the 3rd shell from 1 to 8. They are organized by increasing number of electrons (left to right). Mg Al Na Si P S Cl Ar

10. 11 Consider the preceding two slides. Consult the periodic table. Go back and label each diagram with its atomic symbol or name. Did you observe any connections between the arrangement of the periodic table and your arrangement? Write you answer in this box and below this line. The first set was from the 2 nd row of the periodic table and had electrons in 2 shells. Atoms were sorted by increasing number of electrons in table and in my organization. The first set was from the 3r d row of the periodic table and had electrons in 3 shells. Atoms were sorted by increasing number of electrons in table and in my organization.

11. Both trends observed in the previous slides are present here. Click and drag so that both are shown in columns and rows. What similarities are common to atoms in the same row? In the same column? Atoms is same row have same number of shells. Atoms is same column have same number of electrons in outer shell. What properties are common to all atoms? Inner shells have same numbers of electrons. 1 st shell is 2, 2 nd has 8 electrons, 3 rd has 18. Number of protons = number electrons 12

12. 13 Both trends observed in the previous slides are present here. Click and drag so that both are shown in columns and rows. What similarities are common to atoms in the same row? In the same column? Atoms is same row have same number of shells. Atoms is same column have same number of electrons in outer shell. What properties are common to all atoms? Inner shells have same numbers of electrons. 1 st shell is 2, 2 nd has 8 electrons, 3 rd has 18. Number of protons = number electrons

13. Consider the preceding two slides. What about the periodic table do they illustrate? Write you answer here. The periodic table is arranged based on the arrangement of electrons in shells within the atom. Elements in the same group (and often having similar chemical reactivity) have the same number of electrons in the out-shell. Therefore, we can conclude that the number of electrons in outer shells determines the chemical reactivity of atoms (elemennts). 14