POGIL EXERCISE 05 How Are Electrons Distributed Around the Nucleus of the Atom?

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1 RUN TIME: 50 MIN POGIL 5 Page 1 of 6 POGIL EXERCISE 05 How Are Electrons Distributed Around the Nucleus of the Atom? Each member should locate his/her role in Table 1 and assume his or her role at this time. The new manager takes charge of the POGIL folder and hands out the GRF and RRF to the appropriate members. The new recorder should record the names of the group members on the new GRF and the Reflector should record the start time on her/his form. Table 1. Group Member Role Assignments GROUP TYPE -> GROUPS OF THREE GROUPS OF FOUR MEMBER NO. -> Manager + + Reporter + + Recorder + + Reflector + + Technician Encourager + + SFUC + * + * The manager should direct the members to use two minutes to read the following material. OBSERVATION I. Niels Bohr did some Nobel Prize thinking that was eventually substantiated experimentally about the question as to the location of electrons around the nucleus of an atom. As you already know from a previous POGIL, electrons cannot be viewed as maintaining a planer (flat) orbit around the nucleus. His conclusion was that electrons were arranged in shells around the nucleus. He referred to these shells as principal energy levels. Eventually, seven shells were found or inferred to exist in nature; they were numbered one through seven from near the nucleus (1) to the exterior (7). The shells also increase in energy from one to seven. The outer most shell coincides with the period number of the element in the periodic chart. This means that all elements in Period 1 have only one shell; all elements in period 2 have two shells; etc. You can visualize shells as spheres surrounding the nucleus. 1. What is the maximum number of shells known? 2. How many periods are there in the periodic chart? 3. What is your conclusion from the data of Items 1 and 2? +5 MIN

2 RUN TIME: 50 MIN POGIL 5 Page 2 of 6 4. How many principle energy levels does mercury (Hg) have? Give a reason for your answer. 5. Which element has the most energetic electrons, calcium (Ca) or Iodine (I)? Give a reason for your answer. OBSERVATION II. Electrons are arranged in shells, subshells and orbitals. The orbital is the basic unit structure of electron distribution; each orbital can hold a maximum of 2 electrons. The next level of organization is the subshell. There are four types of subshells designated by the letters: s, p, d, and f. Each subshell contains a specific number of orbitals: The s subshell contains a maximum of one orbital and therefore can hold a maximum of two electrons. The p subshell can contain up to three orbitals for a maximum of six electrons. The d subshell can contain up to five orbitals holding a maximum of ten electrons. Finally, the f subshell can have up to seven orbitals potentially holding 14 electrons. The s and p subshells of the outermost shell (the period number in which the element is located) are the electrons most often involved in chemical reactions. These electrons are called valence electrons and it is these electrons that are diagramed in Lewis diagrams. The other electrons in the d and f subshells are known as core electrons and are not diagramed in the Lewis diagram of the atom since they play a secondary role in the chemical reactivity of the element. The largest structure in electron configuration scheme is known as the shell which constitute the principal energy levels within the atom. Shells are numbered and this number is the period number in which the element falls on the periodic chart. 6. Draw a concept map in Figure I that describes the relationship between orbitals, subshells and shells of an atom (beginning with the smallest moving to the largest). When you re finished, submit your diagram to the instructor for validation. 7. Table 2 summarizes the known electronic configuration of atoms by telling you what type of subshells are present in each shell (period). Complete Table 3 using the information in Observation II and Table What group of elements has the same atomic number as the last cell of each row of Table 3? +25 MIN

3 RUN TIME: 50 MIN POGIL 5 Page 3 of 6 Figure I. Diagram of Electron Configuration Relationships Table 2. Electron Configuration of Atoms Principle PERIOD Contains these Subshells E. Level NUMBER s p d f 1 1 YES NO NO NO 2 2 YES YES NO NO 3 3 YES YES NO NO 4 4 YES YES YES NO 5 5 YES YES YES NO 6 6 YES YES YES YES 7 7 YES NO YES YES +25 MIN

4 RUN TIME: 50 MIN POGIL 5 Page 4 of 6 Table 3. Maximum Electron Capacity of All Known Elements. PERIOD (SHELL) Maximum Number of Electrons in MAXIMUM # E - IN NUMBER s Orbitals p Orbitals d Orbitals f Orbitals SHELL a ATOM b a Maximum number of electrons in shell is equal to sum of values in Columns 2-5. b Maximum number of electrons in Atom for Period 1 is equal to the number if electrons in the shell; for Period 2 the maximum number of electrons in the atom is equal the maximum number in Period 1 + the maximum number in Period 2; etc. Recorders should have the instructor to examine your completed Table 3. After approval, continue processing with Item Arrange the following terms in increasing order of the maximum number of electrons each can hold: orbital, shell, subshell. 10. What special name is given to the outer most s and p electrons? 11. What special name is given to all the other electrons of the atoms? 12. What is the total number of electrons that can be accommodated in s and p orbitals? OBSERVATION III. The electrons of an atom do not add randomly to the various orbitals, shells and subshells. Electrons occupy a certain orbital, subshell, and shell based on the energy they contain. You can determine the electronic configuration of any element by finding the element on the periodic chart (Figure II). 13. Using Figure II as modified by the mini-lecture provided by the instructor, write the Noble Gas configuration for the elements listed in Period 6 of the Periodic Chart by completing Table MIN

5 RUN TIME: 50 MIN POGIL 5 Page 5 of 6 Figure II. Electron Configuration Related to the Periodic Chart EXERCISE END. Managers should collect the GRF, the Recorders POGIL and the RRF, paperclip them together, and place in the left pocket of the folder. The folder should be closed and left on the table. +50 MIN

6 RUN TIME: 50 MIN POGIL 5 Page 6 of 6 Table 4. Electron Configuration and Lewis Diagrams of a Selection of Period 6 Elements. Element Symbol Atomic No. 55 Nobel Gas Electron Configuration Lewis Diagram Gd 64 [Xe] 54 6s 2 4f min