Periodic Table. Engr. Yvonne Ligaya F. Musico 1

Transcription

1 Periodic Table Engr. Yvonne Ligaya F. Musico 1

2 TOPIC Definition of Periodic Table Historical Development of the Periodic Table The Periodic Law and Organization of Elements in a Periodic Table Periodic Properties and Periodic Trends Engr. Yvonne Ligaya F. Musico 2

3 What is Periodic Table? Engr. Yvonne Ligaya F. Musico 3

4 Periodic Table A table of elements written in the order of increasing atomic number and arranged in horizontal rows (periods) and vertical columns (groups) to show similarities in the properties between elements. Engr. Yvonne Ligaya F. Musico 4

5 Historical Development of Periodic Table Engr. Yvonne Ligaya F. Musico 5

6 Johann Wolfgang Dobereiner ( ) He grouped similar elements with almost equal atomic weights into groups of three or TRIADS Example: (Br, I, Cl) (Sr, Ca, Ba) (Se, S, Te) Engr. Yvonne Ligaya F. Musico 6

7 John A. Newlands ( ) He grouped all elements in the order of their atomic weights. He then divided the elements into groups of seven elements (noble gases were unknown at that time) Engr. Yvonne Ligaya F. Musico 7

8 Lothar Meyer ( ) He plotted a graph showing an attempt to group elements according to atomic weights Engr. Yvonne Ligaya F. Musico 8

9 Dmitri Mendeleev ( ) He arranged elements in the order of increasing atomic weights. In this table, the first two periods had seven elements each. The next periods contained seventeen elements each. Engr. Yvonne Ligaya F. Musico 9

10 Dmitri Mendeleev ( ) The discovery of the inert gas during the 1890 s added and additional element to each period. He left spaces for elements that might someday be discovered. He studied the properties of the elements and predicted the properties would be discovered elements. Engr. Yvonne Ligaya F. Musico 10

11 Henry Moseley ( ) He used X-rays to determine the atomic number (proton) of the elements. X-rays are light radiation with high frequency and a short wave length. The higher the atomic number of the elements the shorter the wavelength of X-rays will be when the element is used as a target. Engr. Yvonne Ligaya F. Musico 11

12 Henry Moseley ( ) Resolved discrepancies in Mendeleev s arrangement He concluded that the elements should be arranged in the order of increasing atomic number Engr. Yvonne Ligaya F. Musico 12

13 Periodic Law and Organization of Elements in a Periodic Table Engr. Yvonne Ligaya F. Musico 13

14 Periodic Law This law states that some of the physical and many chemical properties of the elements are periodic functions of their atomic numbers. Engr. Yvonne Ligaya F. Musico 14

15 The Periodic Table The Modern Periodic Table Elements listed in order of increasing atomic number Engr. Yvonne Ligaya F. Musico 15

16 The Periodic Table Group or Families a vertical column of elements contains elements with similar chemical properties these groups are divided into A and B subgroups. the group number in the A subgroup shows this number of valence electron Example: Phosphorus belong to VA so its valence e- is 5 Engr. Yvonne Ligaya F. Musico 16

17 The Periodic Table Periods a horizontal row of elements designated by numbers 1-7 on the side of the periodic table elements are not related chemically the period number denotes the number of main energy level (shell) of the atom. Example: Sodium is in period 3 so its atom is composed of 3 shells and its outermost shell is the 3 rd shell Engr. Yvonne Ligaya F. Musico 17

18 The Periodic Table Engr. Yvonne Ligaya F. Musico 18

19 The Periodic Table Metals Mostly solid except Hg which is liquid at room at temperature Good electrical and thermal conductivity High density, high melting point and boiling point Engr. Yvonne Ligaya F. Musico 19

20 The Periodic Table Metals Combine with non-metals to produce salts Do not combine with each other To the left of the stairstep line that in general separates the metal and non-metals Engr. Yvonne Ligaya F. Musico 20

21 The Periodic Table Metals Example: Na, Cu, Fe, Au, Pb Engr. Yvonne Ligaya F. Musico 21

22 The Periodic Table Metals Stairstep line separating metals from non metal Engr. Yvonne Ligaya F. Musico 22

23 The Periodic Table Non Metals Several exist as gases at room temperature Poor electrical and thermal conductivity Low density, low melting point and boiling point Engr. Yvonne Ligaya F. Musico 23

24 The Periodic Table Non Metals Combine with metals to produce salts Some combine with each other To the right of the of the dark stairstep line that separates the metals from non metals Engr. Yvonne Ligaya F. Musico 24

25 The Periodic Table Non Metals Example: C, N, O, S, Cl, He Engr. Yvonne Ligaya F. Musico 25

26 The Periodic Table Non -Metals Stairstep line separating metals from non metal Engr. Yvonne Ligaya F. Musico 26

27 The Periodic Table Metalloids properties intermediate between those of metals and nonmetals Examples: B, Al, Si, Sb, Sn, Po Engr. Yvonne Ligaya F. Musico 27

28 Group or Families in Periodic Table Alkali metals Group IA Alkaline Earth Metals Group IIA Halogens Group VIIA Boron Family IIIA Carbon Family IVA Nitrogen Family VA Oxygen Family VIA Noble Gases VIIIA Group 0 very stable configuration with 8 e- in the outermost shell except He. Engr. Yvonne Ligaya F. Musico 28

29 The Periodic Table of the Elements Engr. Yvonne Ligaya F. Musico 29

30 Blocks in Periodic Table Representative Elements Noble Gases Transition Elements Inner Transition Elements Engr. Yvonne Ligaya F. Musico 30

31 Representative Elements The A subgroups IA through VIIA These elements, the outer energy level is incomplete and the electrons are occupying s or p orbitals. The electron configuration will be from ns 1 to np 5 (n is the period number) Engr. Yvonne Ligaya F. Musico 31

32 Representative Elements Example a) Sodium (Na) at no. = 11, being 3 and & Group IA. So Na would have one e- in the 3s orbital, configuration in 3s 1 with all lower orbitals being completely filled. b) Nitrogen (N) at no. 7, in the period 2 & in Group VA. So N would have 2e- in the 2s orbitals and 3e- in the 2p 3 with all lower orbital completely filled. Engr. Yvonne Ligaya F. Musico 32

33 Noble Gases Each elements in this group has a completely filled set of s and p orbitals. The electron configuration for the outermost e- is ns 2, np 6 (except He, ns 2 ). This is very stable configuration. Engr. Yvonne Ligaya F. Musico 33

34 Noble Gases Example Krypton (Kr), period 4, group VIIIA Configuration is 4s 2, 4p 6 in the outermost energy level. Engr. Yvonne Ligaya F. Musico 34

35 Transition Elements The series having a set of incomplete d orbitals. These elements are the B subgroups. In general, the outermost energy level here will have an ns2 configuration [except VIB and IB (ns 1 )]. The outermost electron added to the electrons in the inner incomplete d orbital corresponds to the group number in the B subgroups (maximum is 8) Engr. Yvonne Ligaya F. Musico 35

36 Transition Elements Example a) Iron (Fe) - Period 4, group VIIIB - Period 4, the last energy level is the 4 th - Group VIIIB, it has an inner incomplete d orbital in the 3 rd energy level (this d orbital are of one energy level lower). b) In case of Chromium (Cr) group VIB, the configuration is 4s 1, 3d 5. c) For copper (Cu) group IB, the configuration is 4s 1, 3d 10 Engr. Yvonne Ligaya F. Musico 36

37 Inner Transition Elements Two series of elements from 58 to 71 called the Lathanide series and belongs to period 6 from 90 to 110 called Actinide series series and belongs to period 7 In general, these elements have three incomplete energy levels since one electron enters an orbital before the set of orbitals begin filling Engr. Yvonne Ligaya F. Musico 37

38 Inner Transition Elements There are many exceptions to the order of filling of orbitals going across. Consider the following examples: Chlorine (Cl) is a representative element Manganese (Mn) is a transition element Magnesium (Mg) is a representative element Argon (Ar) is a noble gas Uranium (U) is an inner transition element Engr. Yvonne Ligaya F. Musico 38

39 Periodic Properties and Periodic Trends Engr. Yvonne Ligaya F. Musico 39

40 Periodic Properties and Periodic Trends Atomic size Ionization Energy Electron Affinity Electronegativity Engr. Yvonne Ligaya F. Musico 40

41 Atomic Size The size of the atoms become bigger as the number of shells increases. Going down any group in the table there is large increase in atomic size. The increase in the number of energy levels causes the increase in the atomic radius. Engr. Yvonne Ligaya F. Musico 41

42 Atomic Size Going across any period, there is a small but rather decrease in size of the atomic radius. As the atomic number increases, the nuclear charge becomes greater. Each electron is attracted towards the nucleus making it closer to the nucleus causing the decrease in the atomic radius Engr. Yvonne Ligaya F. Musico 42

43 Atomic Size INCREASES I N C R E A S E S Engr. Yvonne Ligaya F. Musico 43

44 Atomic Size Example Using the periodic table, arrange the following elements in order of decreasing atomic size: Br, Sr, Sn, I, Cs, Ba. Solution: Going down the group and across the period the order is Cs, Ba, Sr, Sn, I, Br Engr. Yvonne Ligaya F. Musico 44

45 Atomic Size Engr. Yvonne Ligaya F. Musico 45

46 Ionization Energy The amount of energy required to remove an electron from an atom. Going down the group in the table, the ionization energy decreases from one atom to the next. Going across a period, there is a general increase of ionization energy. Engr. Yvonne Ligaya F. Musico 46

47 Ionization Energy INCREASES I N C R E A S E S Engr. Yvonne Ligaya F. Musico 47

48 Ionization Energy Example: Choose the one with the highest ionization energy: Na, Al, Cl, Br Solution: Cl since this has the smallest atomic size (that is the valence electron is closer to the nucleus) ionization energy is highest. Engr. Yvonne Ligaya F. Musico 48

49 Electron Affinity The amount of energy released when an electron is added to an atom. Going down a group of non-metals such as halogen (Group VIIA) the electron affinity decreases. Going across the period such as from nitrogen to oxygen to flourine, the electron affinity increases. Engr. Yvonne Ligaya F. Musico 49

50 Electron Affinity INCREASES I N C R E A S E S Engr. Yvonne Ligaya F. Musico 50

51 Electronegativity It is defined as the tendency of that atom to attract electrons toward itself Going down a group electronegativity decreases Going down across the period electronegativity increases Engr. Yvonne Ligaya F. Musico 51

52 Electronegativity Low electronegativity is characteristic of metals The lower electronegativity are found at the lower left of the Periodic Table. High electronegativity is a characteristic of non-metals. Fluorine is the most electronegative element. Oxygen is the second. The electronegativity ranges 2.2 to 4.0 Engr. Yvonne Ligaya F. Musico 52

53 Electronegativity INCREASES I N C R E A S E S Engr. Yvonne Ligaya F. Musico 53

54 Electronegativity Example: Arrange the following elements in order of increasing electronegativity: Ba, Br, I, Sn, Sr Solution: Looking at position in the periodic table including the group and period, gives the following order. Ba, Sr, Sn, I, Br Electronegativity ranges between 1.8 & 2.1 Engr. Yvonne Ligaya F. Musico 54

55 ENGR. YVONNE LIGAYA F. MUSICO