Part I Assignment: Electron Configurations and the Periodic Table

Transcription

1 Chapter 11 The Periodic Table Part I Assignment: Electron Configurations and the Periodic Table Use your periodic table and your new knowledge of how it works with electron configurations to write complete electron configurations for the following elements. 1. Cr 2. Zr 3. W 4. Ho 5. Mn 6. Pb 7. S 8. Th 9. Pt 10. Cu

2 Part 2 Notes: Ion Configurations For Representative Elements Example 1a: Write the electron configuration for calcium. Calcium forms a ion by electrons. Which electrons would be lost by the calcium atom to form its ion? The electrons in its outer most energy level, of course. These would be the electrons. Example 1b: Write the electron configuration for the calcium ion. Name Symbol # Protons # electrons Electron Configuration Potassium atom Potassium ion Argon Chlorine atom Chloride Argon and potassium ion are said to be isoelectronic, they have the same electron configuration. Argon and chloride are also isoelectronic. Chloride and potasium ion are isoelectronic. NOTE: Chloride and potassium atom are NOT isoelectronic. Representative elements often for react to form ions that have electron configurations with full s and p sublevels in the highest level. For Transition Elements. Transition elements often form more than one ion. This is because its outer electrons may be lost from both the s and the d orbitals. Transition elements are NOT isoelectronic with noble gases. Consider the element iron and its two ions, iron (II) and iron (III). Name Symbol # protons # electrons Configuration Iron Iron (II) Iron (III) As a general rule, when ions are formed from transition metals, atoms tend to lose electrons from sublevels with the higher energy level (the higher coefficient). Nickel Nickel (II) Nickel (III) Copper Copper (I) Copper (II)

3 Part 2 Assignment: Ion Configurations Write the complete electron configurations for the following elements and ions: 1. strontium ion 2. iodide 3. chromium (II) 4. aluminum 5. telluride 6. zinc ion 7. mercury (II) 8. manganese (II) 9. cobalt (III) 10. With which noble gas is zinc isoelectronic? 11. With which noble gas is telluride isoelectronic? For questions 12-22, write the word true or false in the blank provided. 12. The strontium ion is isoelectronic with xenon. 13. Chloride is isoelectronic with the potassium ion. 14. Nitride is isoelectroic with the aluminum ion. 15. Nitride is isoelectronic with the magnesium ion. 16. Nitride is isoelectronic with oxide. 17. Nitride is isoelectronic with oxygen. 18. Nitrogen is isoelectronic with oxygen. 19. Bromide is isoelectronic with chloride. 20. The rubidium ion is isoelectronic with iodide. 21. Oxide is isoelectronic with helium. 22. The lithium ion is isoelectronic with neon.

4 Part 3 Notes: The Periodic Table Elements first classified by whom? When was it first published? Originally categorized how? What is the Periodic Law? The Modern Periodic Table of Elements How organized? Metallic elements Nonmetallic elements Metalloids Vertical columns = or horizontal rows = - Group 1 - Chemical properties = Physical properties = Charge of ions = End of electron configuration = Reaction with water = Group 2 - Chemical properties = Charge of ions = End of electron configuration = Groups They are given this name because Some common elements = Charge of ions = End of electron configuration =

5 Group 17 - Chemical properties = Charge of ions = End of electron configuration = Group 18 - Chemical properties = Charge of ions = End of electron configuration = Former name = Why inappropriate = Lanthanide series - Elements atomic number to Located = Also classified as part of the Formerly named Misnomer because Actinide Series - Elements atomic number to Located = Also classified as part of the Transuranium element = Representative Element = These elements include groups Elements are representative or. s-block - p-block - d-block - f-block -

6 Part 3 Assignment: The Periodic Table PERIODIC TABLE GRID FOR IDENTIFICATION A J B C E F G H I K B C E F G H I K B C D D D D D D D D D D E F G H I K B C D D D D D D D D D D E F G H I K B C D D D D D D D D D D E F G H I K B C D D D D D D D L L L L L L L L L L L L L L M M M M M M M M M M M M M M Identify the part of the periodic table to which the statement applies by the letter in the boxes. It may need more than one letter. 1. Noble gases 12. Actinide series 2. Halogens 13. Alkali metals 3. Inner transition metals 14. e -1 configuration ends with 5f x 4. Contains only metals 15. p-block 5. Contains only nonmetals 16. Transition metals 6. s-block 17. Least reactive 7. Lanthanide series 18. Most reactive metals 8. Alkaline earth metals 19. Used to be rare earth metals 9. e -1 configuration ends in p f-block 10. d-block 21. Ions of variable charge 11. e -1 configuration ends in s Most reactive nonmetals

7 Part 4A Notes: Ionization Energy The first ionization energy is the energy required to eject the most weakly held electron from an atom resulting in an ion with a +1 charge. Trends in a Period As the atomic number of elements in a period increases, the first ionization energy increases. As the positive charge on the nuclei of elements in a period increases, the first ionization energy increases because there are more protons pulling harder on the number of electrons in the atom; therefore it is more difficult to remove an electron. Deviations to Periodic Trends 1. By studying Table on page, you will find that beryllium has a greater first ionization energy than boron Write the electron configuration for beryllium: Write the electron configuration for boron: It is easier to remove the 2p 1 electron from the boron than it is to remove a 2s 2 electron from beryllium because of the special stability that arises from a completely filled sublevel. The same reasoning may be used to explain the deviation between magnesium and aluminum. The only difference is the principal quantum number of the valence electrons. 2. Nitrogen has a greater first ionization energy than oxygen. Write the electron configuration for nitrogen. Write the electron configuration for oxygen. It takes more energy to remove the 2p 3 electron from nitrogen than it does to remove the 2p 4 electron from oxygen due to the special stability that arises from half-filled sublevels. The same reasoning can be used to explain the deviation between phosphorus and sulfur. The only difference is the principal quantum number of the valence electrons. Trends in a Group In a group, the first ionization energy tends to decrease as atomic number increases. Core shielding makes removal of valence electrons easier. As the atomic number increases, there is increased shielding of the nucleus due to the core electrons. Since the nucleus is being shielded more, it has less and less pull on the valence electrons. Successive Ionization Energies Examine table on page. The energy required to remove a second electron from an atom is known as the second ionization energy and is abbreviated IE 2. The energy required to remove a third electron from the orbital is known as the third ionization energy, abbreviated IE 3. Note that it generally takes a greater amount of energy to remove each additional electron. Also note that it takes large increases in energy to remove core electrons once all valence electrons have been removed. It is much easier to remove valence electrons from an atom than it is to remove core electrons.

8 Part 4B Notes: Atomic Radius We know from our studies that an orbital has no definite size. An orbital is simply a probability map of where an electron is likely to be. We know that an atom consists of a nucleus and electrons which exits in orbitals, outside the nucleus forming an electron cloud. The size of an orbital is not precisely defined, so the size of an atom can not be precisely defined.. However, it is possible to estimate the size of an atom. By studying solid crystalline structures of elements and compounds through a technique known as X-ray diffraction, an estimate of the distance between the different nuclei of the crystal can be obtained. Scientists have also been able to estimate the distance between the nuclei of diatomic molecules. By knowing the distance between nuclei of atoms, scientists may estimate the size of the atom. Atomic Radius is half the distance between the nuclei of atoms. Trends in Atomic Radii As atomic number increases in a period, the atomic radii of the elements in the period tends to decrease. As atomic number increases, the number of protons in the nucleus increases. This increase in protons increases the attractive force between the nucleus and the electrons which causes the electrons to be drawn in closer to the nucleus, decreasing the atomic radius. As atomic number increases in a period, the atomic radii of elements in the group tends to increase. Elements in a group have similar valence electron configurations. The difference between valence electron configurations of elements in a group is that as the atomic number increases, the energy level (n) of the valence electrons increases. The greater the energy level of the valence electrons, the greater the probability of finding those electrons at greater distances from the nucleus. Another factor affecting size of the atom is called shielding. Core electrons shield the valence electrons from the attractive force of the nucleus making it possible for them to move greater distances from the nucleus. Table on page provides an excellent description for the trends of atomic radii for the representative elements. Notes: Ionic Radius You will be using table and and figure from pages to complete these notes. Atoms to Cations The atomic radius of calcium is nanometers. The electron configuration of calcium is: The ionic radius of calcium is nanometers. The electron configuration of the calcium ion is: Note that the calcium atom has electron through the fourth energy level. The calcium ion only has electrons through the third energy level. Because of this there is a much greater probability that the electrons in the calcium ion will be closer to the nucleus than the electrons of the calcium atom. calcium atom calcium ion Number of protons Number of electrons Note that both the calcium atom and the calcium ion have the same number of electrons; however, the calcium ion has two less electrons than the calcium atom. There is less electron repulsion in the calcium ion. Also the 20 protons in the nucleus of the calcium ion can pull the 18 electrons in the ion closer to the nucleus than the 20 protons in the atom can pull the 20 electrons toward the nucleus of that atom.

9 Cations to Cations sodium ion aluminum ion Symbol # electrons # protons ionic radius in nm Electron configuration Note that the aluminum ion has a smaller radius than the sodium ion because the greater the number of protons in aluminum ion nucleus may exert a greater force over the lesser electrons in the sodium ion nucleus. Atoms to Anions The atomic radius of chlorine is nanometers. The electron configuration of chlorine is: The ionic radius of chloride is nanometers. The electron configuration of chloride is: There are more electrons in the outermost orbital of the chloride than in chlorine. Electron repulsion is therefore increased and the electrons move farther away from the nucleus. Number of protons Numbers of electrons chlorine atom chlorine ion Note that both the chlorine atom and the chlorine ion have the same number of protons. The 17 protons in the chlorine atom can pull the 17 electrons closer than the 17 protons in the ion can pull the 18 electrons. Anions to Anions nitride fluoride Symbol # electrons # protons ionic radius in nm Electron configuration Note that there are more protons in the fluoride ion than there are in the nitride ion. The nuclei of both ions are pulling on the same number of electrons. The nucleus with the greatest number of protons is able to pull the electrons closer.

10 Part 4 Assignment: Atomic Radii Circle the element with the greatest atomic radius. 1. sodium or magnesium 2. magnesium or beryllium 3. lithium or rubidium 4. cesium or radon 5. radon or krypton 6. neon or fluorine 7. oxygen or fluorine 8. oxygen or selenium 9. phosphorus or aluminum 10. calcium or barium 11. beryllium or nitrogen 12. boron or gallium 13. chlorine or iodine 14. xenon or neon 15. krypton or potassium 16. strontium or antimony 17. boron or neon 18. fluorine or iodine 19. arsenic or bromine 20. calcium or beryllium 21. In your own words, describe why the increase in atomic number across a period causes a decrease in atomic radius. 22. In your own words, describe why the increase in atomic number down a family causes an increase in atomic radius.

11 Part 5 Assignment: Chapter 11 Summary Questions 1. Place the following in order of increasing size: Cu, Cu +1, Cu Place the following in order of decreasing size: Ni +2, Pd +2, Pt Which of the following have noble gas configurations: Fe +2, Sc +3, Tl +1, Te -2, Cr Consider atoms of the following elements: F, Ne, Na, Mg, and Al a. Which has the smallest first ionization energy? b. Which has the largest first ionization energy? c. Which has the largest second ionization energy? d. Which has the largest third ionization energy? 5. Pretend your periodic table contained an element (X) with an atomic number of 113. a. Write its electron configuration. b. What element will it most closely chemically resemble? c. With which of the following elements will it most likely form compounds: Na, Mg, Al, N, O, F. d. Write compounds to indicate the formulas of the compounds indicated by the above question.