Chapter 8

1. Chapter 8 “Introduction to the PERIODIC TABLE”

2. 8.1 The Modern Periodic Table Objectives • Describe the kinds of information provided by the periodic table. • Explain the structure of the periodic table in terms of the periods and groups • Generalize about the properties of metals, nonmetals, and metalloids on the periodic table. • Organize data to develop a table of atomic masses.

3. The Modern Periodic Table • Imagine looking for the answer to a homework question in a book with no table of contents! You would have to thumb through the book-page by page. • Why is it easier to find information in a book with a table of con tents? • Data that have been organized are easier to find, compare, and interpret.

4. The Modern Periodic Table • One kind of table you use often is a calendar. • Think of the calendar as a grid made up of horizontal rows and vertical columns. Each column represents a different day of the week. Each day is repeated in every row through the whole month. • This arrangement of the days in the month is periodic. Things that are periodic have a regular, repeating pattern.

5. The Modern Periodic Table • Like the days of the month, the chemical elements can be arranged in a way that shows a repeating, or periodic, pattern. • The chemical properties of the elements repeat as the elements increase in atomic number. • A table that shows these patterns in the elements' properties is called a periodic table.

6. The Modern Periodic Table

7. The Modern Periodic Table • At that time, chemists had identified about 70 elements. • Mendeleev wrote each element's name, atomic mass, and properties on a card. He ordered the cards from lowest to highest atomic mass and pinned them to his laboratory wall. • He grouped elements that had similar properties and put these cards in rows along the wall. • In 1869, a Russian chemist named Dmitri Mendeleev created the first periodic table of the elements.

8. The Modern Periodic Table

9. The Modern Periodic Table • Arranging the elements in this way, Mendeleev ran into several problems. • So, he left spaces where no element seemed to fit and put question marks in these spaces. • Mendeleev predicted the properties of elements that would be discovered to fill in the blank spaces. • One element he left space for, gallium, was discovered in 1875.

10. The Modern Periodic Table • After Mendeleev's death, a British physicist named Henry Moseley carried on Mendeleev's work. • Moseley arranged the elements in order of increasing atomic number instead of atomic mass. He discovered that the pattern had no irregularities. • The position of an element in the modern periodic table is related to its atomic number and the arrangement of electrons in its energy levels.

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19. Science & Technology

20. 8.2 Metals Objectives • Describe common properties of metals. • Generalize about the trend in Groups 13 through 16. • Classify metals using the periodic table.

21. Properties of Metals • Metals share many of the same properties. • Most metals are silvery or gray in color. When polished, they usually have a surface that reflects light, a quality called luster. • Luster is one of the properties of metals. • Metals also conduct heat and electricity.

22. Properties of Metals • Most metals are hard and have high melting points, but there are many exceptions. • For example, pure gold and pure silver are relatively soft, so they are not often used alone in jewelry and coins. • A few metals, such as gallium, have melting points that aren't much higher than room temperature. • One metal, mercury, is actually a liquid at room temperature.

23. Properties of Metals • One of the most useful properties of metals is malleability. • Materials that are malleable can be flattened, bent, and shaped without breaking. Aluminum, for example, can be flattened into foil. • Most metals are also ductile. • They can be pulled into wire.

24. Properties of Metals • Why do metals share all these properties? • Atoms have their electrons arranged in different energy levels. The electrons in the highest energy level are most important, because they determine an element's properties. • Although metals have very different total numbers of electrons, most have from one to three electrons in the highest energy level.

25. Properties of Metals • This low number of outer electrons is what gives metals their properties. • A metal atom gives up its outer electrons very easily. • When many metal atoms are combined, they all share their outer electrons. • These electrons move in a "cloud" around the metal atoms. As a result, a metal can change shape without breaking.

26. Properties of Metals • The metal atoms slide past each other.. • This behavior makes metals ductile and malleable. • And they conduct electricity because the electrons are free to move.

27. Life Science Link

28. Alkali Metals • Group 1 in the periodic table contains six elements known as the alkali metals. • The alkali metals are very reactive. • They all have just one electron in the highest energy level of their atoms. • Because this electron is so easily lost, alkali metals are found in nature only as positively-charged ions. They combine with negatively-charged ions to form salts.

29. Alkali Metals • Table salt is made of sodium ions and ions of the element chlorine. • In pure form, all of the alkali metals have similar properties. For example, they are so soft that they can be cut easily with a knife. • They have low densities and melt at low temperatures. Cesium, in fact, will melt on a hot day.

30. Alkaline Earth Metals • The six elements in Group 2 are called the alkaline earth metals. • Alkaline earth metals are reactive, but they are not as reactive as the alkali metals. • Alkaline earth metal atoms have two electrons in the highest energy level. • Like the alkali metals, they occur in nature as ions combined with other elements.

31. Alkaline Earth Metals • Magnesium and calcium are common alkaline earth metals. • Calcium compounds make up much of your bones and teeth. • These elements are also used to make building materials, such as cement. • The shells of sea animals also contain calcium. • The compound magnesium hydroxide, also called milk of magnesia, is used to soothe upset stomachs.

32. Transition Metals • Most transition metals are shiny. • They have high melting points and are good conductors of heat and electricity. • Because of the arrangement of their outer electrons, transition metals are much less reactive than the alkali or alkaline earth metals. • They can, however, combine with other elements.

33. Transition Metals • Groups of transition metals share similar properties. • For example, iron, cobalt, and nickel are the only metals with magnetic properties. • Transition metals are often found in ores. Ores are minerals containing relatively large amounts of metal compounds.

34. Rare-Earth Metals • The elements located in the two separate rows at the bottom of the periodic table are the rare-earth metals. • The lanthanide series, elements 58-71 , follows lanthanum in Period 6. • The actinide series, elements 90-103, follows actinium in Period 7.

35. Rare-Earth Metals • Except for element 61, all of the lanthanides occur in nature. • Most of the actinides, however, are synthetic, or made in laboratories. • All these elements are radioactive. The most common and known element is Uranium. Uranium is used as nuclear fuel when its converted into plutonium, through a nuclear reaction.

36. Check & Explain pg. 193 Answer questions 1 & 2

37. 8.3 Nonmetals & Metalloids Objectives • Identify the groups containing nonmetals and metalloids. • Explain why nonmetals have different properties than metals. • List the nonmetals essential to life. • Communicate in a chart the different properties of metals, nonmetals, and metalloids.

38. Nonmetals & Metalloids Did you know your life depends on nonmetals? Look to the right of the zigzag line in the periodic table - in Periods 2 and 3, locate carbon, nitrogen, oxygen, sulfur, and phosphorus. These five nonmetals make up much of your body.

39. Nonmetals & Metalloids Together with hydrogen, they form fats, carbohydrates, proteins, and nucleic acids- the building blocks of living things.

40. Nonmetals & Metalloids • Metalloids also play an important role in daily life. • For example, silicon is used to make computer chips. • These chips are used in computers, watches, calculators, and even cars.

41. Properties of Nonmetals and Metalloids • Unlike metals, nonmetals do not have luster and are poor conductors of heat and electricity. • Solid nonmetals are usually dull and brittle. • They are neither malleable nor ductile, Many nonmetals are gases at room temperature.

42. Properties of Nonmetals and Metalloids • Most nonmetals have many electrons in their highest energy levels. • They are held tightly by the nucleus and not free to move around. • The atoms of many nonmetals tend to accept electrons from other elements. • Many form negatively-charged ions.

43. Properties of Nonmetals and Metalloids • Metalloids have properties of both metals and nonmetals. • All the metalloids are shiny solids, but they do not have as much luster as the metals. • Most conduct heat and electricity, but not as well as metals.

44. Boron Group • The only element in Group 13 that is not a metal is boron. • Boron is a brittle, black metalloid. • It is used to make boric acid, a mild antiseptic and laundry products.

45. Boron Group • Below Boron in the periodic table is aluminum. • Aluminum, metal has many uses because it is light, soft, and easy to cut. It also conducts heat and electricity very well.

46. Boron Group • Aluminum is the most abundant metal in the earth's crust. However, extracting aluminum from bauxite, its major ore, requires great amounts of energy.

47. Boron Group • The other elements in the boron group are the uncommon metals gallium, indium, and thallium.

48. Carbon Group • How is the lead in your pencil like a diamond? • Both are made of carbon. • Carbon is the only nonmetal in Group 14. • It has two common forms: graphite and diamond. Graphite makes up much of the "lead" in your pencil.

49. Carbon Group • Carbon is unique because it can form an unlimited number of different compounds. • Most of the compounds found in living things contain carbon.

50. Carbon Group • Silicon and germanium are metalloids. • The silicon compounds in rocks and soil make up 60 percent of the earth's crust. • Tin and lead are both metals. They are both obtained from mining ore. • "Tin" cans are steel food containers lined with tin. • Lead and its compounds are poisonous.