Table of Contents

1. Table of Contents • Introduction to Atoms • Organizing the Elements • Metals • Nonmetals and Metalloids • Elements From Stardust

3. - Elements and Atoms The Building Blocks of Matter • Matter may consist of elements, compounds, or mixtures.

4. - Elements and Atoms Atomic Theory and Models • Dalton thought that atoms were like smooth, hard balls that could not be broken into smaller pieces.

5. - Elements and Atoms Atomic Theory and Models • Thomson suggested that atoms had negatively charged electrons embedded in a positive sphere.

6. - Elements and Atoms Atomic Theory and Models • Rutherford was surprised that a few particles were deflected strongly. This led him to propose an atomic model with a positively charged nucleus.

7. - Elements and Atoms Atomic Theory and Models • Through the first part of the twentieth century, atomic models continued to change.

8. - Elements and Atoms Outlining Elements and Atoms • As you read, make an outline about elements and atoms. Use the red headings for the main ideas and the blue headings for the supporting ideas. • The Building Blocks of Matter • Elements, Compounds, and Mixtures • Particles of Elements • Atomic Theory and Models • Dalton’s Atomic Theory • Thomson and Smaller Parts of Atoms • Rutherford and the Nucleus • Bohr’s Model • A Cloud of Electrons • The Modern Atomic Model

9. - Elements and Atoms More on Atomic Structure • Click the PHSchool.com button for an activityabout atomic structure.

12. - Introduction to Atoms Structure of an Atom • A carbon atom consists of protons and neutrons in a nucleus that is surrounded by electrons.

13. - Introduction to Atoms Models of Atoms • For over two centuries, scientists have created models of atoms in an effort to understand why matter behaves as it does. As scientists have learned more, the model of the atom has changed.

14. - Introduction to Atoms Isotopes • Atoms of all isotopes of carbon contain six protons, but they differ in the number of neutrons. Carbon-12 is the most common isotope.

15. - Introduction to Atoms Previewing Visuals • Before you read, preview Figure 2. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions. Structure of an Atom Q. What particles are in the center of the atom? A. Protons and neutrons Q. What particles move around the outside of the nucleus? A. Electrons

16. - Introduction to Atoms More on Atoms • Click the PHSchool.com button for an activity about atoms.

18. End of Section:Introduction to Atoms

19. End of Section:Elements and Atoms

20. - Atoms, Bonding, and the Periodic Table Valence Electrons and Bonding • The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms.

21. - Atoms, Bonding, and the Periodic Table The Periodic Table • Elements are organized into rows and columns based on their atomic number.

22. - Atoms, Bonding, and the Periodic Table Periodic Table Activity • Click the Active Art button to open a browser window and access Active Art about the periodic table.

23. - Atoms, Bonding, and the Periodic Table The Periodic Table • As the number of protons (atomic number) increases, the number of electrons also increases. As a result, the properties of the elements change in a regular way across a period.

24. - Atoms, Bonding, and the Periodic Table The Periodic Table • The variety of colors in a “neon” sign results from passing an electric current through sealed glass tubes containing different noble gases.

25. Key Terms: Key Terms: Examples: Examples: halogen atomic number alkali metal period group family noble gas - Atoms, Bonding, and the Periodic Table Building Vocabulary • After you read the section, reread the paragraphs that contain definitions of Key Terms. Use the information you have learned to write a definition of each Key Term in your own words. Key Terms: Examples: valence electrons Valence electrons are electrons that are of the highest energy level and are held most loosely. A halogen is any element in Group 17, which consists of elements with seven valence electrons. The atomic number of an element is the number of protons in the nucleus of an atom. electron dot diagram The symbol for the element surrounded by dots that stand for valence electrons is an electron dot diagram. A alkali metal is any element in Group 1, which consists of elements with one valence electron. A row of elements across the periodic table is called a period. chemical bond A chemical bond is the force of attraction that holds two atoms together as a result of the rearrangement of electrons between them. Elements in the same column are called a group or family. A noble gas is any element in Group 18, which consists of elements with eight valence electrons. symbol Each element is represented by a symbol, usually consisting of one or two letters.

26. End of Section:Atoms, Bonding, and the Periodic Table

27. - Organizing the Elements Finding Data on Elements • Each square of the periodic table includes an element’s atomic number, chemical symbol, name, and atomic mass.

28. - Organizing the Elements Periodic Table Activity • Click the Active Art button to open a browser window and access Active Art about the periodic table.

29. - Organizing the Elements Organization of the Periodic Table • The 18 columns of the periodic table reflect a repeating pattern of properties that generally occur across a period.

30. - Organizing the Elements Asking Questions • Before you read, preview the red headings. In a graphic organizer like the one below, ask a what or how question for each heading. As you read, write answers to your questions. Question Answers What pattern of elements did Mendeleev discover? Patterns appeared when the elements were arranged in order of increasing atomic mass. Atomic number, chemical symbols and names, and average atomic mass What data about elements is found in the periodic table? How are elements organized in the periodic table? Elements are organized in periods and groups based on their properties.

31. End of Section:Organizing the Elements

32. - Metals Metals in the Periodic Table • The metals in Group 1, from lithium to francium, are called the alkali metals. Alkali metals react with atoms of other elements by losing one electron.

33. - Metals Metals in the Periodic Table • Group 2 of the periodic table contains the alkaline earth metals. These elements are not as reactive as the metals in Group 1, but they are more reactive than most other metals.

34. - Metals Melting Points in a Group of Elements • The properties of elements within a single group in the periodic table often vary in a certain pattern. The following graph shows the melting points of Group 1 elements (alkali metals) from lithium to francium.

35. Melting points decrease from lithium to francium. Reading Graphs: As you look at Group 1 from lithium to francium, describe how the melting points of the alkali metals change. - Metals Melting Points in a Group of Elements

36. New element 119 should have a melting point of approximately 25ºC. Predicting: If element number 119 were synthesized, it would fall below francium in Group 1 of the periodic table. Predict the approximate melting point of new element 119. - Metals Melting Points in a Group of Elements

37. None of the alkali metals are liquids at room temperature. Cesium and francium might melt if you could hold them in your hand. Interpreting Data: Room temperature is usually about 22ºC. Human body temperature is 37ºC. Which of the alkali metals are liquids at room temperature? Which might melt if you could hold them in your hand? - Metals Melting Points in a Group of Elements

38. - Metals Metals in the Periodic Table • The transition metals are less reactive than the metals in Groups 1 and 2.

39. - Metals Metals in the Periodic Table • Only some of the elements in Groups 13 through 15 of the periodic table are metals. These metals are not nearly as reactive as those on the left side of the table.

40. - Metals Metals in the Periodic Table • Lanthanides are soft, malleable, shiny metals with high conductivity.

41. - Metals Metals in the Periodic Table • The elements below the lanthanides are called actinides. Many of these elements are so unstable that they last for only a fraction of a second after they are made.

42. - Metals Using Prior Knowledge • Before you read, write what you know about metals in a graphic organizer like the one below. As you read, write what you learn. What You Know Metals are shiny. Some metals are magnetic. What You Learned Ductile metals can be pulled into a wire. Alkali metals react by losing one electron.

43. - Metals Links on Metals • Click the SciLinks button for links on metals.

44. End of Section:Metals

45. - Nonmetals and Metalloids Properties of Nonmetals • When nonmetals react with metals, one or more electrons move from the metal atoms to the nonmetal atoms.

46. - Nonmetals and Metalloids Families of Nonmetals • Each element in the carbon family has atoms that can gain, lose, or share four electrons when reacting with atoms of other elements.

47. - Nonmetals and Metalloids Families of Nonmetals • Group 15, the nitrogen family, contains two nonmetals: nitrogen and phosphorus. These non-metals usually gain or share three electrons when reacting with atoms of other elements.

48. - Nonmetals and Metalloids Families of Nonmetals • Group 16, the oxygen family, contains three nonmetals: oxygen, sulfur, and selenium. These elements usually gain or share two electrons when reacting with atoms of other elements.

49. - Nonmetals and Metalloids Families of Nonmetals • The Group 17 elements are the most reactive nonmetals. Atoms of these elements easily form compounds by sharing or gaining one electron when reacting with atoms of other elements.

50. - Nonmetals and Metalloids Families of Nonmetals • The elements in Group 18 are known as the noble gases. They do not ordinarily form compounds because atoms of noble gases do not usually gain, lose, or share electrons.