Experiment 11 - Electron Configurations and Orbital Diagrams

Experiment 11: Electron configurations and Orbital diagrams -Electron spin and the Pauli exclusion principle -Building up principle -Electron configurations -Orbital diagrams, Hund’s rule Learning Goals: • To analyze and explain if an orbital diagram follows the Pauli exclusion principle and Hund’s rule • To understand how to write electron configurations and orbital diagrams. • To relate orbital diagrams with magnetic properties. Background information and theory: According to the Bohr model of the atom, an atom consists on a very dense nucleus that contains positive particles called protons, and neutral particles called neutrons. Around this dense nucleus negatively charged particles called electrons are found in orbits or shells of specific energy. The mass of these electrons is about 1/1800 the mass of a proton. The shells where the electrons are found are labeled with a number n (principal quantum number). These shells contain subshells and the subshells consist in orbitals where we can find the electrons. The electron configuration of an atom or ion is a short description of the location of the electrons in different shells and subshells. The ground-state electron configuration is the configuration associated with the lowest energy level of the atom. To write the ground state electron configuration of atom electrons are added to the different shells and subshells using the Aufbau principle or building up principle (see diagram below) 7s 7p 7d 7f 6s 6p 6d 6f 5s 5p 5d 5f 4s 4p 4d 4f 3s 3p 3d 2s 2p 1s START HERE When using this diagram, electrons will be first added to the lowest energy level (1s) where up to two electrons can be placed (s subshell). If more electrons need to be accommodated, they will occupy the different subshells according to the diagram. Superscripts next to the subshell indicate how many electrons have been placed in that subshell. The maximum occupancy for a p subshell is 6 electrons, for a d subshell is 10 and for an f subshell is 14 electrons. For example, the electron configuration of Lithium is written as: 1s2 2s1 Other configurations different than the ground state configuration are called excited state configurations. These are higher in energy. The electron configuration gives you limited information as it tells about the shell and subshell occupancy. An orbital diagram shows you the distribution of the electrons in the different orbitals. In an orbital diagram, an orbital is represented by either a circle or a line. Electrons are represented as arrows. For example, the orbital diagram for an atom of Lithium will be: 1s 2s In some diagrams, the orbitals are placed in order of increasing energy. Orbital diagrams are useful to predict magnetic properties of elements. A paramagnetic substance has at least one electron alone in an orbital. A diamagnetic substance has all electrons paired up in the orbital diagram. According to this, then Lithium is a paramagnetic substance. When adding electrons in an orbital diagram the electrons must be added with different spins (one pointing up the other down, Pauli exclusion principle). When electrons are added to degenerated orbitals, orbital with the same energy as the 3 p orbitals in a p subshell, these electrons will occupy different orbitals before they pair up (Hund’s rule). The electron configuration of carbon is 1s2 2s2 2p2.and its orbital diagram will look like: 2p 2s 1s From this diagram we can see that carbon is paramagnetic. Electron configurations and Orbital Diagrams Data Substance 1: 1) For the first substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 2) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, there is at least two electrons in each circle and in different directions. 3) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, it follows the same sequence of each shells according to order. 4) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain No, because no electron were alone in the orbital. 5) Write the ground state electron configuration for substance 1. 1s^2,2s^2,2p^2 6) What element is substance 1 according to the ground-state electron configuration you wrote? Carbon Substance 2: 7) For the second substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 8) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, because there are two electrons in each orbital. 9) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, because it is following the correct shell order. 10) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain No, because no electrons were alone in their orbital. 11) Write the ground state electron configuration for substance 2. 1s^2, 2s^2 ,2p^6, 3s^2 12) What element is substance 2 according to the ground-state electron configuration you wrote? Magnesium Substance 3: 13) For the third substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 14) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, because there are two electrons in each orbital. 15) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, because it is following the correct shell order. 16) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain No, because no electrons in their own orbital 17) Do you expect this substance to be paramagnetic or diamagnetic? Explain Yes, because there were no unpaired electrons. Substance 4: 18) For the fourth substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 19) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, because there are two electrons in each orbital and have the same quantum number, even though there is only one electron occupying a shell. 20) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. no, because it is not following the correct shell order. 21) Write the electron configuration for substance 4 according to the orbital diagram in the video. 1s^2, 2s^2 , 2p^6, 3s^2 , 3p^6 22) Substance 4 has two positive charges on it. What is the identity of substance 4 according to the electron configuration you wrote? (Hint: cations are formed by removing electrons from the shell with the largest principal quantum number, n) Aragon 23) According to the orbital diagram, do you expect this substance to be paramagnetic or diamagnetic? Explain Paramagnetic, because there only two electrons with their own shell. Substance 5: 24) For the fifth substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 25) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, because there are two electrons in each orbital and have the same quantum number, even though there is only one electron occupying a shell. 26) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, because it is following the correct shell order. 27) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain Yes, Because the last two orbitals are singly occupied 28) Write the ground state electron configuration for substance 5. 1s^2 , 2s^2, 2p^2 29) What element was substance 5 according to the ground state electron configuration? Carbon 30) Do you expect this substance to be paramagnetic or diamagnetic? Explain Paramagnetic, because there are electrons that are not paired. Substance 6: 31) For the sixth substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 32) Is this diagram possible according to the Pauli exclusion principle? Explain. Yes, because there are two electrons in each orbital and have the same quantum number, even though there is only one electron occupying a shell. 33) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, because it is following the correct shell order. 34) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain Yes, Because the last three orbitals are singly occupied 35) Write the ground state electron configuration for substance 6 1s^2, 2s^2, 2p^6, 3s^2 , 3p^6, 3d^6 36) What element is substance 6 according to the ground state electron configuration? Iron 37) Do you expect this substance to be paramagnetic or diamagnetic? Explain Paramagnetic, because some of the electrons in the orbits do not have a pair Substance 7: 38) For the seventh substance, draw an orbital diagram like the one in the video. Don’t forget sato label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 39) Is this diagram possible according to the Pauli exclusion principle? Explain. No, all of the electrons have their own orbital and are singular 40) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. No, the order is incorrect the diagram skipped a shell level. Substance 8: 41) For the eighth substance, draw an orbital diagram like the one in the video. Don’t forget to label each subshell as 1s, 2s, 2p, etc. Use circles, squares or lines to represent orbitals and arrows to represent electrons. 42) Is this diagram possible according to the Pauli exclusion principle? Explain. No, two of the electrons are going to the same polarity direction 43) Observe the order in which the electrons were added to the diagram. Does this example follow the Aufbau principle? Explain. Yes, the diagram has the correct shell order. 44) Observe the process of adding electrons to the orbitals in the orbital diagram, does it follow Hund’s rule? Explain No, it violates Hund’s rule by the number of electrons in each orbit Electron configurations and Orbital Diagrams Postlab questions: Your instructor may ask you to answer these in your lab notebook, or to answer directly on this page and turn it in, or to include these answers in a formal lab report. Follow your instructor’s directions. 1. Write the electron configuration of the following atoms or ions: Na 1s^2, 2s^2, 2p^6, 3s^1________________________________________________ N3- ___1s^2,2s^2, 2p^6_____________________________________________ Mn 1s^2, 2s^2, 2p^6, 3s^2, ____________________________________________ 3p^6, Zn2+ ___1s^2, 2s^2, 2p^6, 3s^2, 3d^8_____________________________________________ 4s^2, 3p^6, 3d^5 4s^2, 2. What is the noble gas electron configuration of the following atoms and ions? Fe3+ 1s^2 , 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^3 Si 1s^2, 2s^2, 2p^6, 3s^2, 3p^2 F 1s^2, 2s^2, 2p^6 Se21s^2 , 2s^2, 2p^6, 3s^2 ,3p^6, 4s^2, 3d^10, 4p^6 3. Draw the orbital diagram for Se. Write the electron configuration and indicate if the element is paramagnetic or diamagnetic 1s^2 , 2s^2, 2p^6, 3s^2 ,3p^6, 4s^2, 3d^10, 4p^4 Diamagnetic