Chapter #2 The Periodic Table

Transcription

1 Chapter #2 The Periodic Table Mendeleeve ( ), arranged the elements within a group in order of their atomic mass. He noted repeating patterns in their physical and chemical properties Periodic Table of Elements Chemistry: A Volatile History BBC Four Element Song in Japanese Element Song Nov 17 10:47 AM Henry Moseley ( ), Arranged the elements in a table by order of Atomic Numbers. Alternative Periodic Tables Nov 17 10:47 AM 1

2 Periods the horizontal rows of the periodic table Groups or Families the vertical columns of the periodic table Periodic Law when elements are arranged in order of increasing atomic number, a periodic pattern occurs in their physical and chemical properties Nov 17 10:50 AM Metals Most elements on the P.T. are metals. Physical Properties of Metals: Luster (shininess) Good conductors of heat and electricity High density (heavy for their size) High melting point Ductile (most metals can be drawn out into thin wires) Malleable (most metals can be hammered into thin sheets) Chemical Properties of Metals: Easily lose electrons Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting) Nov 17 10:51 AM 2

3 Nonmetals Nonmetals are found to the right of the stair step line. Their characteristics are opposite those of metals. Physical Properties of Nonmetals: No luster (dull appearance) Poor conductor of heat and electricity Brittle (breaks easily) Not ductile Not malleable Low density Low melting point Many are gases at room temperature. Chemical Properties of Nonmetals: Tend to gain electrons Since metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other. Nov 17 10:57 AM Metalloids Elements on both sides of the steps have properties of both metals and nonmetals. These elements are called metalloids or semimetals. Physical Properties of Metalloids: Solids Can be shiny or dull Ductile Malleable Conduct heat and electricity better than nonmetals but not as well as metals Nov 17 10:57 AM 3

4 The transition metals are the metallic elements that serve as a bridge, or transition, between the two sides of the table. The lanthanides and the actinides at the bottom of the table are sometimes known as the inner transition metals Nov 17 10:57 AM Main Blocks of the P.T Groups 1 and 2 of the P.T are referred to as the s block because these elements have outer electrons in an s orbital. Groups are the p block because these elements have outer electrons in the p orbitals. Also called the representative elements. Groups 3 12 are referred to as the d block and the inner transition elements are f block. Jan 5 10:29 AM 4

5 Valence Electron(s) electron(s) in the outermost energy level of an atom. In a period from L to R on the P.T the number of valence electrons increases by one. In a group, the group number is related to the umber of valence electrons. Nov 17 10:53 AM The Alkali metals group 1 of the P.T, are very reactive metals. They do not occur freely in nature. They have only 1 valence electron in their last energy level. The Alkaline Earth metals group 2 of the P.T. These metals have 2 valance electrons in their last energy level. THE NOBLE GASES The gases in column 18 or 8. All of the Noble gases are inert. They have 8 electrons on their last energy level, (except for He with 2 electrons). Noble gases rarely combine with other elements. Nov 17 10:58 AM 5

6 HALOGENS Located in column 7 or 17 of the P.T. The halogens have 7 e in their last energy level. They are all just one electron short of having a full shell. (8 valance electrons) They often bond with metals and elements from Group 1 of the P.T When a halogen combines with another element, the resulting compound is called a halide. Nov 17 2:14 PM Boron Family Group 3 or 13. They have 3 e s in the last energy level. Boron is a metalloid. The other members of this family are metals. The Carbon family Group 4 or 14. All members of the carbon family have 4 e s in their last energy level. The Nitrogen family Group 5 or 15. All members of the nitrogen family have 5 e s in their last energy level. The Oxygen family Group 6 or 16. All members of the nitrogen family have 6 e s in their last energy level. Their properties go from nonmetallic in oxygen and sulfur to metalloid in tellurium to metallic in polonium. Nov 17 2:14 PM 6

7 Periodic Trends: Reactivity Alkalie Metals Li, Na, K Alkaline Metals Halogens Reaction of Na & Cl 2 Reactivity of Halogens Nov 22 11:49 PM Atomic Radius is half the distance between the nuclei of two atoms in a homonuclear diatomic molecule. Atomic Radius Trends Atomic size generally increase as we move down the group. Atomic size generally decrease as we move from left to right across the period. Nov 22 11:49 PM 7

8 Jan 13 9:27 PM Atomic Radius Trend Graph Atomic Radius Trends Practice: 1. Which of the following has a greater atomic radius? a. Na, Li b. Sr, Sb c. C, Te d. Se, Po 2. Arrange the elements in order of increasing atomic radius a. S, Cl, Al, Na b. Mg, Sr, F, B c. Bi, Cs, Ba, I d. P, F, Ra, Cs Nov 23 12:04 AM 8

9 Ionic Radius Ions will have a different size than the atoms they come from. Positive ions are smaller than the atoms they come from. Nov 23 12:06 AM Negative ions are bigger than the atoms they come from. Ionic Radius Trends Practice 1. Which of the following has a greater ionic radius? a. Na +, Li + b. Sr 2+, Al 3+ c. O 2, S 2 d. K +, P 3 2. Arrange the elements in order of decreasing ionic radius a. S 2, Cl, Al 3+, Na + b. Mg 2+, Sr 2+, F, B 3+ Nov 23 12:06 AM 9

10 The Octet Rule and Common Ions Draw the Bohr ring models for: Li and F Jul 14 10:32 AM Ionization Energy the energy required to remove an electron from a gaseous atom. I. E. Trends The first ionization energy generally decreases as we move down the group. The first ionization energy generally increases as we move from left to right across the period. Nov 29 7:37 AM 10

11 I. E. Trends Practice Arrange the elements in order of increasing ionization energy a. S, Cl, Al, Na b. Mg, Sr, F, B c. Bi, Cs, Ba, I d. P, F, Ra, Cs Successive IE Nov 29 7:39 AM Second Ionization Energy Second ionization energy is defined by the equation: It is the energy needed to remove a second electron from gaseous 1+ ion to give gaseous 2+ ion. You can then have as many successive ionization energies as there are electrons in the original atom. The first four ionization energies of aluminum, for example, are given by 1st I.E. = 577 kj mol 1 2nd I.E. = 1820 kj mol 1 3rd I.E. = 2740 kj mol 1 4th I.E. = kj mol 1 Dec 6 9:55 PM 11

12 Electron Affinity Trend the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion. H(g) + e H (g); ΔH = 73 kj/mol. Electron Affinity Trends Electron Affinity energy generally decreases as we move down the group. Electron Affinity energy generally increases as we move from left to right across the period. Jul 25 1:47 PM Electron Affinity Trends Practice Arrange the elements in order of increasing electron affinity a. O, F, N, Mg b. K, Si, Cl, Al c. Rb, Sn, Sr, I d. P, Br, Ca, Li Jul 25 1:56 PM 12

13 Electronegativity the ability of an atom to attract electrons to itself when it is chemically combined with another element. Values are 0 4 Electronegativity Trends: Generally decreases as you go down the family. Generally increases as you move from left to right across a period Dec 2 10:41 AM Electronegativity Trends Practice Arrange the elements in order of increasing electron affinity a. O, F, N, Mg b. K, Si, Cl, Al c. Rb, Sn, Sr, I d. P, Br, Ca, Li Dec 2 10:41 AM 13

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