Chapter 6 Organizing the Elements THE PERIODIC TABLE AND PERIODIC LAW Periodic Table Summary Sheet For the Periodic Table above indicate each of the following TRENDS: atomic size and ionic size Na Na + F F - Ne Energy Level ( shielding ) # p + ( attractions ) # e - ( repulsions ) < < < < Shielding Effect Lessened ability of nucleus to attract outer e- due to repulsions of other e - in between. metallic character nonmetallic character CHEMISTRY Scotch Plains-Fanwood High School Page 1
Ionization Energy Energy required to remove an electron from a gaseous atom or ion. (Always remove e- from highest energy level 1 st transition metals are TRICKY! Don t be that person that forgets!) Mn +2 Mn +3 Exceptions to Ionization Energy trend: Compare: 1 st IE of Mg with 1 st IE of Al 1 st IE of N with 1 st IE of O Look for big jump to determine # valence e - Compare: 2 nd IE of Na with 2 nd IE of Mg Electron Affinity Energy absorbed by a gaseous atom or ion to gain an electron. Electronegativity Attraction for electrons IN A BOND. CHEMISTRY Scotch Plains-Fanwood High School Page 2
Periodic Table Review Sheet Elements are arranged in order to an increase in atomic number. *** Periodic Law: properties of elements are a periodic function of their atomic numbers. A. Periods go across: elements in the same period = have the same # of principal energy levels with electrons in them B. Groups go down (also called families) = families of elements share similar properties = each element in a family has the same number of valence electrons. Metals: to the left of the zig zag line most active metal=fr (bottom left) metals have Low ionization energies, have Low electronegativities, Lose electrons, Luster, Lower Left form positive ions, are good conductors, most are solids, they are malleable and ductile. Nonmetals: to the right of the zig zag line most active nonmetal = F (top right, group 17, not 18) nonmetals have high ionization energies, have high electronegativities, gain electrons, form negative ions when with metals, share electrons with nonmetals, lack luster, are brittle, are poor conductors. Metalloids: touch the zig zag line (not Al and Po) have some properties of both metals and nonmetals Noble Gases: (group 18) monatomic gases that don t usually react with other elements. Kr and Xe can form compounds with F or O Have complete outer (valence) shell of electrons= stable configuration, stable octet Have dispersion forces between molecules (weak forces of attraction). Dispersion forces increase with larger mass, so boiling point of Kr is higher than He Ions: ions do not have equal number of protons and electrons as atoms do + ions= less electrons than protons (+1 charge indicates one lost electron from the atom) - ions= more electrons than protons (-1 charge indicates one gained electron to the atom) Allotropes: forms of the same element that have different molecular formulas,different physical properties and chemical properties. Ex: Carbon can be in many forms, coal, diamond, graphite, Oxygen and ozone. Properties of substances: Physical Color, odor, solubility, MP, BP, hardness, conductivity, phase, density Chemical Combustibility, reactivity, reaction rate Things you can observe without changing the substance into something else Things that describe how an element reacts in a chemical reaction CHEMISTRY Scotch Plains-Fanwood High School Page 3
Groups: Elements in the same group react similarly because they have the same number of valence electrons. Down a group radius increases due to an increase in the number of shells that hold electrons. Electronegativity and ionization energy decreases down a group. For metals, activity increases down a group because the electrons become more shielded by inner shells, making it harder to hold onto the valence electrons. Group 17: halogens= most active nonmetals (gain electrons easiest) Group 18: noble gases= mostly inactive, stable electron configurations.periods: as you go across a period (L->R) atomic radius generally decreases electronegativity and ionization energy increase across a period due to increase in nuclear charge. More positive protons in the nucleus means a tighter hold on the negative electrons. 11. Ionization energy: the amount of energy required to remove the atom s most loosely held electron. Lower IE, easier to take away electrons. IE decreases down a group (due to more energy levels of electrons=more shielding) IE increases across a period (due to increase in nuclear charge which pulls electrons in tighter) 12. Electronegativity: the attraction of a nucleus for electrons (higher electronegativity=tighter hold on e - ) Electronegativity decreases down a group (due to more energy levels of electrons=more shielding) Electronegativity increases across a period (due to increase in nuclear charge which pulls electrons in tighter) 13. Atomic radius: half the distance between nuclei that are next to each other. (or the distance between the nucleus and the valence electrons) radius increases down a group due to increased number of energy levels (more electron shells) radius decreases across a period (due to increase in nuclear charge which pulls electrons in tighter) 14. Ionic radius: Metals Since metals lose electrons to become ions, the ionic radii for metals are smaller than the radii for metal atoms Nonmetals Since nonmetal atoms gain electrons to become ions, the ionic radii for nonmetals are larger than the radii for the nonmetal atoms loses electrons Metal atom metal ion (+) Gains electrons Nonmetal atom ion (-) nonmetal CHEMISTRY Scotch Plains-Fanwood High School Page 4
Periodic Table Worksheet 1. Where are the most active metals located? 2. Where are the most active nonmetals located? 3. As you go from left to right across a period, the atomic size (decreases/increases). Why?. 4. As you travel down a group, the atomic size (decreases/increases). Why?. 5. A negative ion is (larger/smaller) than its parent atom. Why?. 6. A positive ion is (larger/smaller) than its parent atom. Why?. 7. As you go from left to right across a period, the first ionization energy generally (decreases/increases). Why?. 8. As you go down a group, the first ionization energy generally (decreases/increases). Why?. 9. Where is the highest electronegativity found?. 10. Where is the lowest electronegativity found?. 11. Elements of Group 1 are called. 12. Elements of Group 2 are called. 13. Elements of Groups 3-12 are called. 14. As you go from left to right across the Periodic Table, the elements go from (metals/nonmetals) to (metals/nonmetals). 15. Group 17 elements are called. 16. The most active element in Group 17 is. 17. Group 18 elements are called. 18. What sublevels are filling across the Transition Elements? 19. Elements within a group have similar number of. 20. Elements across a series [period] have the same number of. 21. A colored ion generally indicates a. 22. As you go down a group, the elements generally become (more/less) metallic. 23. The majority of elements on the Periodic Table are (metals/nonmetals). 24. Elements on the Periodic Table are arranged according to their. 25. An element with both metallic and nonmetallic properties is called a. CHEMISTRY Scotch Plains-Fanwood High School Page 5
Name Class Date The Periodic Table ELECTRONS AND THE STRUCTURE OF ATOMS 6.1 Organizing the Elements Essential Understanding Although Dmitri Mendeleev is often credited as the father of the periodic table, the work of many scientists contributed to its present form. Reading Strategy Compare and Contrast Organizing information in a table helps you compare and contrast several topics at one time. For example, you might compare and contrast different groups of elements. As you read, ask yourself, How are they similar? How are they different? As you read Lesson 6.1, use the compare and contrast table below. Fill in the table with increases or decreases to show the patterns of the listed periodic trends. Across a period Down a group Metallic Nonmetallic Atomic number EXTENSION On a blank periodic table, use arrows and labels to illustrate the results in your compare and contrast table. Lesson Summary Searching for an Organizing Principle As more and more elements were discovered, scientists needed a way to classify them. Elements were first classified according to their properties. Mendeleev s Periodic Table Mendeleev developed the first periodic table, arranging elements according to a set of repeating, or periodic, properties. Elements were also placed in order, according to increasing atomic mass. Mendeleev used his table to predict the properties of yet undiscovered elements. Today s Periodic Table Today s periodic table is a modification of Mendeleev s periodic table. The modern periodic table arranges elements by increasing atomic number. Periodic law states that when elements are ordered by increasing atomic number, their chemical and physical properties repeat in a pattern. CHEMISTRY Scotch Plains-Fanwood High School Page 6
Name Class Date Metals, Nonmetals, and Metalloids Within the periodic table, elements are classified into three large groups based on their properties. Metals are good conductors and many are ductile and malleable. Nonmetals are mostly gases whose properties are opposite to those of metals. Metalloids can behave like metals or nonmetals, depending on the conditions. After reading Lesson 6.1, answer the following questions. Searching for an Organizing Principle 1. How many elements had been identified by the year 1700? 2. What caused the rate of discovery to increase after 1700? 3. What did chemists use to sort elements into groups? Mendeleev s Periodic Table 4. Who was Dmitri Mendeleev? 5. What property did Mendeleev use to organize the elements into a periodic table? 6. Is the following sentence true or false? Mendeleev used his periodic table to predict the properties of undiscovered elements. Today s Periodic Table 7. How are the elements arranged in the modern periodic table? 8. Is the following statement true or false? The periodic law states that when elements are arranged in order of increasing atomic number, there is a periodic repetition of physical and chemical properties. Metals, Nonmetals, and Metalloids 9. Explain the color coding of the squares in the periodic table in Figure 6.4. 10. Which property below is NOT a general property of metals? a. ductile c. malleable b. poor conductor of heat d. high luster CHEMISTRY Scotch Plains-Fanwood High School Page 7
Name Class Date 11. Is the following statement true or false? The variation in properties among metals is greater than the variation in properties among nonmetals. 12. Under some conditions, a metalloid may behave like a. Under other conditions, a metalloid may behave like a. 6.2 Classifying the Elements Essential Understanding A periodic table shows much information about an element in an element s square, and arranges elements by their electron configuration. Lesson Summary Reading the Periodic Table An element s square has the element s symbol and name, atomic number and mass, and electron configuration. The elements are grouped into alkali metals, alkaline earth metals, and halogens. Electron Configurations in Groups The properties of elements are largely determined by the arrangement of electrons, or electron configuration, in each atom. Based on their electron configurations, elements are classified as noble gases, representative elements, transition metals, or inner transition metals. After reading Lesson 6.2, answer the following questions. Reading the Periodic Table 1. Label the sample square from the periodic table below. Use the labels element name, element symbol, atomic number, and average atomic mass. 2. List three things, other than the name, symbol, atomic number, and average atomic mass, you can discover about an element using the periodic table in Figure 6.9. a. b. c. Electron Configurations in Groups 3. Is the following sentence true or false? The subatomic particles that play the key role in determining the properties of an element are electrons. 4. Why are Group A elements called representative elements? CHEMISTRY Scotch Plains-Fanwood High School Page 8
Name Class Date 5. Classify each of the following elements as a(n) alkali metal, alkaline earth metal, halogen, or noble gas. a. sodium d. fluorine b. chlorine e. xenon c. calcium f. potassium 6. For elements in each of the following groups, how many electrons are in the highest occupied energy level? a. Group 3A b. Group 1A c. Group 8A 7. Complete the table about classifying elements according to the electron configuration of their highest occupied energy level. Category Description of Electron Configuration Noble gases Representative elements 8. Circle the letter of the elements found in the p block. s sublevel and nearby d sublevel contain electrons s sublevel and nearby f sublevel contain electrons a. Groups 1A and 2A and helium c. transition metals b. Groups 3A, 4A, 5A, 6A, 7A, and 8A except for helium Match the category of elements with an element from that category. d. inner transition metals 9. noble gases 10. representative elements 11. transition metals 12. inner transition metals a. gallium b. nobelium c. argon d. vanadium 13. Use Figure 6.9. Write the electron configurations for the following elements. a. magnesium b. cobalt c. sulfur CHEMISTRY Scotch Plains-Fanwood High School Page 9
6.3 Periodic Trends Essential Understanding An element s properties are related to its position on the periodic table, and these properties follow trends on the table. Name Class Date Lesson Summary Trends in Atomic Size Atomic size is an atom s atomic radius, or one-half the distance between two like atoms when they are joined together. Atomic size generally increases from top to bottom within a group because the number of energy levels increases. Atomic size decreases from left to right across a period because electrons are added to the same energy level and are pulled closer to the nucleus by increasing numbers of protons. Ions Ions form when atoms gain or lose electrons. A positively charged cation forms when an atom loses one or more electrons. A negatively charged anion forms when an atom gains one or more electrons. Trends in Ionization Energy Ionization energy is a measure of how much energy is required to remove an electron from an atom. First ionization energy is the amount of energy required to remove one electron from a neutral atom. Ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period. Trends in Ionic Size Trends in ionic size are based on the fact that metals tend to lose electrons, and nonmetals tend to gain electrons. A cation is smaller than the atom that formed it; an anion is larger than the atom that formed it. Ionic size generally increases from top to bottom within a group and decreases from left to right across a period. Trends in Electronegativity Electronegativity is a measure of an atom s ability to attract an electron when the atom is bonded to another atom. The trends in electronegativity are similar to the trends in ionization energy. Electronegativity tends to decrease from top to bottom within a group and to increase from left to right across a period. CHEMISTRY Scotch Plains-Fanwood High School Page 10
Name Class Date 6 Self-Check Activity For Questions 1 11, complete each statement by writing the correct word or words. If you need help, you can go online. 6.1 Organizing the Elements 1. Early scientists first sorted elements into groups according to their. 2. In Mendeleev s periodic table, elements were arranged by increasing. 3. Currently, elements are arranged on the periodic table according to increasing. 4. Each element is either a metal, a(n), or a metalloid. 6.2 Classifying the Elements 5. The periodic table contains much information about the elements, including their, names, and information about the structure of their atoms. 6. Elements can be sorted into groups with similar properties based on their. 6.3 Periodic Trends 7. Atomic size increases from top to bottom within a(n) and from left to right across a(n) of the periodic table. 8. with a positive or negative charge forms when electrons are transferred from one atom to another. 9. The first ionization energy of atoms tends to from top to bottom within a group and from left to right across a period. 10. When an atom loses one or more electrons to form an ion, the ion is than the original atom; when an atom gains one or more electrons to form an ion, the ion is than the original atom. 11. Trends in electronegativity follow the same pattern as trends in. If You Have Trouble With Question 1 2 3 4 5 6 7 8 9 10 11 See Page 160 161 162 164 167 170 174 176 177 179 181 CHEMISTRY Scotch Plains-Fanwood High School Page 11
Name Class Date Review Vocabulary Match each of the following with its location on the periodic table, using letters a i. Use each choice only once. 1. alkali metals 2. alkaline earth metals 3. halogens 4. inner transition metals 6. metals 7. noble gases 8. nonmetals 9. transition metals 5. metalloids Use the letters j m to show periodic trends in the following properties. The arrows point in the direction the properties increase. Two letters should be in each blank. 10. atomic radius 11. electronegativity 13. size of anion 14. size of cation 12. ionization energy j k m l CHEMISTRY Scotch Plains-Fanwood High School Page 12