The Periodic Table and Periodic Law

Transcription

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2 The Periodic Table and Periodic Law Section 6.1 Development of the Modern Periodic Table Section 6.2 Classification of the Elements Section 6.3 Periodic Trends Click a hyperlink or folder tab to view the corresponding slides. Exit

3 Section 6.1 Development of the Modern Periodic Table (cont.) periodic law group period representative elements transition elements metal alkali metals alkaline earth metals transition metal inner transition metal lanthanide series actinide series nonmetals halogen noble gas metalloid

4 Section 6.1 Development of the Modern Periodic Table Trace the development of the periodic table. Identify key features of the periodic table. atomic number: the number of protons in an atom The periodic table evolved over time as scientists discovered more useful ways to compare and organize the elements.

5 Development of the Periodic Table In the 1700s, Lavoisier compiled a list of all the known elements of the time.

6 Development of the Periodic Table (cont.) The 1800s brought large amounts of information and scientists needed a way to organize knowledge about elements. John Newlands proposed an arrangement where elements were ordered by increasing atomic mass.

7 Development of the Periodic Table (cont.) Newlands noticed when the elements were arranged by increasing atomic mass, their properties repeated every eighth element. This was called the law of octaves.

8 Development of the Periodic Table (cont.) Meyer and Mendeleev both demonstrated a connection between atomic mass and elemental properties. When creating his periodic table, Mendeleev left blank spaces for elements that had not yet been discovered. Using periodic properties of the other elements, he correctly predicted the properties of scandium, gallium, and germanium.

9 Development of the Periodic Table (cont.) Moseley rearranged the table by increasing atomic number, and resulted in a clear periodic pattern our modern periodic table. Periodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic number is called periodic law.

10 Development of the Periodic Table (cont.)

11 The Modern Periodic Table The modern periodic table contains boxes which contain the element's name, symbol, atomic number, and atomic mass.

12 The Modern Periodic Table (cont.) Columns of elements are called groups. Rows of elements are called periods. Elements in groups 1,2, and possess a wide variety of chemical and physical properties and are called the representative elements. Elements in groups 3-12 are known as the transition metals. Elements are classified as metals, non-metals, and metalloids.

13 Metals Metals are elements that are generally shiny when smooth and clean, solid at room temperature, good conductors of heat and electricity, malleable, and ductile. Alkali metals are all the elements in group 1 except hydrogen, and are very reactive. Alkaline earth metals are in group 2, and are also highly reactive.

14 Metals (cont.) The transition elements are divided into transition metals and inner transition metals. The two sets of inner transition metals are called the lanthanide series and actinide series and are located at the bottom of the periodic table.

15 Nonmetals Non-metals are elements that are generally gases or brittle, dull-looking solids, and poor conductors of heat and electricity. Group 17 is composed of highly reactive elements called halogens. Group 18 gases are extremely unreactive and commonly called noble gases.

16 Metalloids Metalloids have physical and chemical properties of both metals and non-metals, such as silicon and germanium. The metalloids form a staircase that separates the metals from the nonmetals, with the exception of aluminum which is a metal.

17 The Modern Periodic Table

18 Section 6.1 Assessment What is a row of elements on the periodic table called? A. octave B. period C. group D. transition A B A. A B. B C. C 0% 0% 0% 0% D. D C D

19 Section 6.1 Assessment What is silicon an example of? A. metal B. non-metal C. inner transition metal D. metalloid A B A. A B. B C. C 0% 0% 0% 0% D. D C D

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21 Section 6.2 Classification of the Elements Explain why elements in the same group have similar properties. Identify the four blocks of the periodic table based on their electron configuration. valence electron: electron in an atom's outermost orbitals; determines the chemical properties of an atom Elements are organized into different blocks in the periodic table according to their electron configurations.

22 Organizing the Elements by Electron Configuration Recall electrons in the highest principal energy level are called valence electrons. Groups can help determine how many valence electrons an atom has.

23 Organizing the Elements by Electron Configuration (cont.) Group 1 elements have 1 valence e- and group 2 elements have 2 valence e-. The number of valence electrons for elements in groups is ten less than their group number. Remember, the maximum number of valence e- is 8.

24 Organizing the Elements by Electron Configuration (cont.)

25 The s-, p-, d-, and f-block Elements The shape of the periodic table becomes clear if it is divided into blocks representing the atom s energy sublevel being filled with valence electrons.

26 The s-, p-, d-, and f-block Elements (cont.) The periodic table can be used to determine the electron configurations and valence electrons of all elements. There are some exceptions to the order of filling orbitals in the d and f orbitals. Ex: Cr and Cu

27 The s-, p-, d-, and f-block Elements (cont.) The Noble Gases are the only elements that have completely filled orbitals. He has 2 valence e- and the other noble gases all have 8 valence e-.

28 Section 6.2 Assessment Which of the following is NOT one of the elemental blocks of the periodic table? A. s-block B. d-block C. g-block D. f-block A B A. A B. B C. C 0% 0% 0% 0% D. D C D

29 Section 6.2 Assessment Which block spans 14 elemental groups? A. s-block B. p-block C. f-block D. g-block A B A. A B. B C. C 0% 0% 0% 0% D. D C D

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31 Section 6.3 Periodic Trends Compare period and group trends of several properties. Relate period and group trends in atomic radii to electron configuration. principal energy level: the major energy level of an atom ion ionization energy octet rule electronegativity Trends among elements in the periodic table include their size and their ability to lose or attract electrons

32 Atomic Radius Atomic size is a periodic trend influenced by electron configuration. For metals, atomic radius is half the distance between adjacent nuclei in a crystal of the element or between the nuclei of identical elements in a molecule.

33 Atomic Radius (cont.) There is a general decrease in atomic radius from left to right, caused by increasing positive charge in the nucleus the nucleus pulls the electrons in tighter. Valence electrons are not shielded from the increasing nuclear charge because no additional electrons come between the nucleus and the valence electrons.

34 Atomic Radius (cont.)

35 Atomic Radius (cont.) Atomic radius generally increases as you move down a group. The outermost orbital size increases down a group, making the atom larger.

36 Ionic Radius An ion is an atom or bonded group of atoms with a positive or negative charge. When atoms lose electrons and form positively charged ions, they always become smaller for two reasons: 1. The loss of a valence electron can leave an empty outer orbital resulting in a small radius. 2. Electrostatic repulsion decreases allowing the electrons to be pulled closer to the nucleus.

37 Ionic Radius (cont.) When atoms gain electrons, they can become larger, because the addition of an electron increases electrostatic repulsion.

38 Ionic Radius (cont.) The ionic radii of positive ions generally decrease from left to right. The ionic radii of negative ions generally decrease from left to right, beginning with group 15 or 16.

39 Ionic Radius (cont.) Both positive and negative ions increase in size moving down a group.

40 Ionization Energy Ionization energy is defined as the energy required to remove an electron from a gaseous atom. The energy required to remove the first electron is called the first ionization energy.

41 Ionization Energy (cont.)

42 Ionization Energy (cont.) Removing the second electron requires more energy, and is called the second ionization energy. Each successive ionization requires more energy, but it is not a steady increase.

43 Ionization Energy (cont.)

44 Ionization Energy (cont.) The ionization at which the large increase in energy occurs is related to the number of valence electrons. First ionization energy increases from left to right across a period. First ionization energy decreases down a group because atomic size increases and less energy is required to remove an electron farther from the nucleus.

45 Ionization Energy (cont.)

46 Ionization Energy (cont.) The octet rule states that atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons. The octet rule is useful for predicting what types of ions an element is likely to form.

47 Electronegativity The electronegativity of an element indicates its relative ability to attract electrons in a chemical bond. Electronegativity decreases down a group and increases left to right across a period. Metals have low electronegativites and nonmetals have high electronegativites.

48 Electronegativity (cont.)

49 Section 6.3 Assessment The lowest ionization energy is the. A. first B. second C. third D. fourth A B A. A B. B C. C 0% 0% 0% 0% D. D C D

50 Section 6.3 Assessment The ionic radius of a negative ion becomes larger when: A. moving up a group B. moving right to left across period C. moving down a group D. the ion loses electrons A B A. A B. B C. C 0% 0% 0% 0% D. D C D

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52 Chemistry Online Study Guide Chapter Assessment Standardized Test Practice Image Bank Concepts in Motion

53 Key Concepts Section 6.1 Development of the Modern Periodic Table The elements were first organized by increasing atomic mass, which led to inconsistencies. Later, they were organized by increasing atomic number. The periodic law states that when the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties. The periodic table organizes the elements into periods (rows) and groups (columns); elements with similar properties are in the same group.

54 Key Concepts Section 6.1 Development of the Modern Periodic Table (contd.) Elements are classified as either metals, nonmetals, or metalloids.

55 Key Concepts Section 6.2 Classification of the Elements The periodic table has four blocks (s, p, d, f). Elements within a group have similar chemical properties. The group number for elements in groups 1 and 2 equals the element s number of valence electrons. The energy level of an atom s valence electrons equals its period number.

56 Key Concepts Section 6.3 Periodic Trends Atomic and ionic radii decrease from left to right across a period, and increase as you move down a group. Ionization energies generally increase from left to right across a period, and decrease as you move down a group. The octet rule states that atoms gain, lose, or share electrons to acquire a full set of eight valence electrons. Electronegativity generally increases from left to right across a period, and decreases as you move down a group.

57 The actinide series is part of the A. s-block elements. B. inner transition metals. C. non-metals. D. alkali metals. A B A. A B. B C. C 0% 0% 0% 0% D. D C D

58 In their elemental state, which group has a complete octet of valence electrons? A. alkali metals B. alkaline earth metals C. halogens D. noble gases A B A. A B. B C. C 0% 0% 0% 0% D. D C D

59 Which block contains the transition metals? A. s-block B. p-block C. d-block D. f-block A B A. A B. B C. C 0% 0% 0% 0% D. D C D

60 An element with a full octet has how many valence electrons? A. two B. six C. eight D. ten A B A. A B. B C. C 0% 0% 0% 0% D. D C D

61 How many groups of elements are there? A. 8 B. 16 C. 18 D. 4 A B A. A B. B C. C 0% 0% 0% 0% D. D C D

62 Which group of elements are the least reactive? A. alkali metals B. inner transition metals C. halogens D. noble gases A B A. A B. B C. C 0% 0% 0% 0% D. D C D

63 On the modern periodic table, alkaline earth metals are found only in. A. group 1 B. s-block C. p-block D. groups A B A. A B. B C. C 0% 0% 0% 0% D. D C D

64 Unreactive gases are mostly found where on the periodic table? A. halogens B. group 1 and 2 C. group 18 D. f-block A B A. A B. B C. C 0% 0% 0% 0% D. D C D

65 Bromine is a member of the A. noble gases. B. inner transition metals. C. earth metals. D. halogens. A B A. A B. B C. C 0% 0% 0% 0% D. D C D

66 How many groups does the d-block span? A. two B. six C. ten D. fourteen A B A. A B. B C. C 0% 0% 0% 0% D. D C D

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87 Table 6.4 Figure 6.5 Noble Gas Electron Configuration The Periodic Table Figure 6.11 Trends in Atomic Radii Figure 6.18 Trends in Electronegativity

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