2. 6.1 Organizing the Elements > 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Chapter 6 The Periodic Table 6.1 Organizing the Elements 6.2 Classifying the Elements 6.3 Periodic Trends

3. 6.1 Organizing the Elements > 2 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. How can you organize and classify elements? CHEMISTRY & YOU If you have ever played a card game, then you have probably organized your cards. Maybe you classified them by color or number.

4. 6.1 Organizing the Elements > 3 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Searching for an Organizing Principle How did chemists begin to organize the known elements? Searching for an Organizing Principle

5. 6.1 Organizing the Elements > 4 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Searching for an Organizing Principle In 1829, a German chemist, J. W. Dobereiner, published a classification system. In his system, the known elements were grouped into triads. A triad is a set of three elements with similar properties. Early chemists used the properties of elements to sort them into groups. –The elements shown here formed one triad. Chlorine, bromine, and iodine may look different, but they have very similar chemical properties.

6. 6.1 Organizing the Elements > 5 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. A few elements, including copper, silver, and gold, have been known for thousands of years and are in a triad known as the “coinage” metals. There were only 13 elements identified by the year 1700. Searching for an Organizing Principle –Chemists suspected that other elements existed. –As chemists began to use scientific methods to search for elements, the rate of discovery increased. –In one decade (1765–1775), chemists discovered five new elements.

7. 6.1 Organizing the Elements > 6 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Dobereiner noted a pattern in his triads. One element in each triad tended to have properties with values that fell midway between those of the other two elements. For example, the average of the atomic masses of chlorine and iodine is [(35.453 + 126.90)/2], or 81.18 amu. This value is close to the atomic mass of bromine, which is 79.904 amu. Searching for an Organizing Principle

8. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Why was it important for scientists to find a logical way to organize the elements?

9. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Why was it important for scientists to find a logical way to organize the elements? Finding a logical way to organize the elements made it possible for scientists to determine how many elements they were looking for.

10. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. In 1869, a Russian chemist and teacher, Dmitri Mendeleev, published a table of the elements. Mendeleev’s Periodic Table He wrote the properties of each element on a separate note card. This approach allowed him to move the cards around until he found an organization that worked.

11. 6.1 Organizing the Elements > 10 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev’s Periodic Table How did Dmitri Mendeleev organize his periodic table? Mendeleev’s Periodic Table

12. 6.1 Organizing the Elements > 11 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev arranged the elements in his periodic table in order of increasing atomic mass (size). Elements in a periodic table are arranged into groups based on a set of repeating properties. Mendeleev’s Periodic Table

13. 6.1 Organizing the Elements > 12 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev’s Periodic Table Mendeleev arranged elements with similar properties in the same row.

14. 6.1 Organizing the Elements > 13 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev’s Periodic Table Notice the two question marks between zinc (Zn) and arsenic (As). Mendeleev left spaces in his table because he knew that bromine belonged with chlorine and iodine.

15. 6.1 Organizing the Elements > 14 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev’s Periodic Table He predicted that elements would be discovered to fill those spaces, and he predicted what their properties would be based on their location in the table.

16. 6.1 Organizing the Elements > 15 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. There was a very close match between the predicted properties and the actual properties of these elements. The match in properties helped convince scientists that Mendeleev’s periodic table was a powerful tool. Mendeleev’s Periodic Table The elements between zinc and arsenic were gallium and germanium, which were discovered in 1875 and 1886, respectively.

17. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Why was Mendeleev’s periodic table an improvement over Dobereiner’s triad classification system and other earlier systems?

18. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Why was Mendeleev’s periodic table an improvement over Dobereiner’s triad classification system and other earlier systems? Mendeleev’s periodic table could encompass all known elements and accurately predicted the existence and properties of undiscovered elements.

19. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. In a periodic table based on atomic mass, iodine should come before tellurium since iodine has a smaller atomic mass than tellurium does. However, based on its chemical properties, iodine belongs in a group with bromine and chlorine. Today’s Periodic Table

20. 6.1 Organizing the Elements > 19 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev placed tellurium before iodine in his periodic table. He assumed that the atomic masses for iodine and tellurium were incorrect, but they were not. A similar problem occurred with other pairs of elements. The problem wasn’t with the atomic masses but with using atomic mass to organize the periodic table. Today’s Periodic Table

21. 6.1 Organizing the Elements > 20 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Mendeleev developed his table before scientists knew about the structure of atoms. He didn’t know that the atoms of each element contain a unique number of protons. Recall that the number of protons is the atomic number. Today’s Periodic Table

22. 6.1 Organizing the Elements > 21 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table How is the modern periodic table organized? Today’s Periodic Table

23. 6.1 Organizing the Elements > 22 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table In the modern periodic table, elements are arranged in order of increasing atomic number. 12345671234567

24. 6.1 Organizing the Elements > 23 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table The elements are arranged in order starting with hydrogen, which has atomic number 1. 12345671234567

25. 6.1 Organizing the Elements > 24 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table There are seven rows, or periods, in the table. Each period corresponds to a principal energy level. 12345671234567

26. 6.1 Organizing the Elements > 25 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table There are seven rows, or periods, in the table. There are more elements in higher- numbered periods because there are more orbitals in higher energy levels. 12345671234567

27. 6.1 Organizing the Elements > 26 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table There are seven rows, or periods, in the table. The different areas on the table correspond to obital shapes. 12345671234567 s f d p s

28. 6.1 Organizing the Elements > 27 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. The properties of the elements within a period change as you move across a period from left to right. The pattern of properties within a period repeats as you move from one period to the next. Today’s Periodic Table

29. 6.1 Organizing the Elements > 28 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. The properties of the elements within a period change as you move across a period from left to right. The pattern of properties within a period repeats as you move from one period to the next. This pattern gives rise to the periodic law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. Today’s Periodic Table

30. 6.1 Organizing the Elements > 29 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Today’s Periodic Table Elements that have similar chemical and physical properties end up in the same column in the periodic table. A column on the table is called a Group/Family. When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.

31. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Are elements with similar properties found in the rows (periods) or columns (groups/families) of the modern periodic table?

32. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Are elements with similar properties found in the rows (periods) or columns (groups/families) of the modern periodic table? Elements with similar properties are found in the columns, or groups/families, of the modern periodic table.

33. 6.1 Organizing the Elements > 32 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Metals, Nonmetals, and Metalloids What are the three broad classes of elements? Metals, Nonmetals, and Metalloids

34. 6.1 Organizing the Elements > 33 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Three classes of elements are metals, nonmetals, and metalloids. Across a period, the properties of elements become less metallic and more nonmetallic. Metals, Nonmetals, and Metalloids

35. 6.1 Organizing the Elements > 34 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Periodic tables are sometimes color-coded to classify types of elements. Metals, Nonmetals, and Metalloids

36. 6.1 Organizing the Elements > 35 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Don’t forget a key.

37. 6.1 Organizing the Elements > 36 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Yellow squares in the table shows that most elements are metals—about 80%. Metals, Nonmetals, and Metalloids

38. 6.1 Organizing the Elements > 37 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Blue is used to identify the non-metals. Metals, Nonmetals, and Metalloids

39. 6.1 Organizing the Elements > 38 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Green is used to identify the metalloids. Metals, Nonmetals, and Metalloids

40. 6.1 Organizing the Elements > 39 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Metals are generally good conductors of heat and electric current. Metals, Nonmetals, and Metalloids Metals Copper is second only to silver as a conductor of electric current. The copper used in electrical cables must be 99.99 percent pure.

41. 6.1 Organizing the Elements > 40 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. A freshly cleaned or cut surface of a metal will have a high luster, or shine. The shine is caused by the metal’s ability to reflect light. All metals are solids at room temperature, except for mercury (Hg). Metals, Nonmetals, and Metalloids Metals

42. 6.1 Organizing the Elements > 41 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Most metals are malleable, meaning that they can be hammered into thin sheets without breaking. Metals, Nonmetals, and Metalloids Metals Many metals are ductile, meaning that they can be drawn into wires.

43. 6.1 Organizing the Elements > 42 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. There is a greater variation in physical properties among nonmetals than among metals. Nonmetals Metals, Nonmetals, and Metalloids Most nonmetals are gases at room temperature, including the main components of air—nitrogen and oxygen. A few are solids, such as sulfur and phosphorus. One nonmetal, bromine, is a dark-red liquid.

44. 6.1 Organizing the Elements > 43 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Nonmetals tend to have properties that are opposite to those of metals. Nonmetals Metals, Nonmetals, and Metalloids In general, nonmetals are poor conductors of heat and electric current. Carbon, in the form of graphite, is an exception to this rule. Solid nonmetals tend to be brittle, meaning that they will shatter if hit with a hammer.

45. 6.1 Organizing the Elements > 44 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. The variation among nonmetals makes it difficult to describe one set of general properties that will apply to all nonmetals. Nonmetals Metals, Nonmetals, and Metalloids A diamond, which is composed of carbon, is very hard. Some match heads are coated with phosphorus, a brittle solid.

46. 6.1 Organizing the Elements > 45 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. There is a heavy stair-step line that separates the metals from the nonmetals. Metalloids Metals, Nonmetals, and Metalloids These elements are metalloids.

47. 6.1 Organizing the Elements > 46 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. A metalloid generally has properties that are similar to those of metals and nonmetals. Metals, Nonmetals, and Metalloids Metalloids

48. 6.1 Organizing the Elements > 47 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Under some conditions, metalloids may behave like metals. Under other conditions, they may behave like nonmetals. The behavior can often be controlled by changing the conditions. Metals, Nonmetals, and Metalloids Metalloids

49. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Like most nonmetals, pure silicon is a poor conductor of electric current. However, if a small amount of boron is mixed with the silicon, the mixture is a good conductor of electric current. Metals, Nonmetals, and Metalloids Metalloids Silicon is also present as the compound silicon dioxide in glass items. Silicon can be cut into wafers and used to make computer chips.

50. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Is there more variety of properties among metals or among nonmetals?

51. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Is there more variety of properties among metals or among nonmetals? The properties of metals are more constant. There is more variety among the properties of nonmetals.

52. 6.1 Organizing the Elements > 51 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Early chemists used the properties of elements to sort them into groups. Mendeleev arranged the elements in his periodic table in order of increasing atomic mass. In the modern periodic table, elements are arranged in order of increasing atomic number. Three classes of elements are metals, nonmetals, and metalloids. Key Concepts

53. 6.1 Organizing the Elements > 52 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. END OF 6.1

54. 6.1 Organizing the Elements > 53 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Glossary Terms periodic law: when the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties metal: one of a class of elements that are good conductors of heat and electric current; metals tend to be ductile, malleable, and shiny

55. 6.1 Organizing the Elements > 54 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Glossary Terms nonmetal: an element that tends to be a poor conductor of heat and electric current; nonmetals generally have properties opposite to those of metals metalloid: an element that tends to have properties that are similar to those of metals and nonmetals

56. 6.1 Organizing the Elements > 55 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.. Periodic tables may contain each element’s name, symbol, atomic number, and atomic mass. BIG IDEA Electrons and the Structure of Atoms