1. History, Groups, and Info on the Periodic Table 8/24/10 GPS Standards: SC4. Students will use the organization of the Periodic Table to predict properties of elements. b.Compare and contrast trends in the chemical and physical properties of elements and their placement on the Periodic Table

2. Part I: History of the PT by 1860, more than 60 elements had been discovered (this is almost 40 years before the Thomson model debuted). however, there was no uniform way established to measure atomic masses accurately, and therefore… chemical formulas were almost impossible to determine correctly. September 1860—Germany—group of chemists assembled to settle the issue of atomic mass (and other misunderstood atomic matters). Cannizarro, Stanislao—presented accurate method to measure atomic mass. Mendeleev, Dimitri—1869—used this new information to organize and arrange the elements (this is the 1st time it was attempted). Cannizarro

3. arranged the elements according to known properties and in order of increasing atomic weight he noticed a trend—by arranging elements in 6 rows, he noticed a repeat in their properties down each column (this is known as a periodic pattern). Mendeleev

4. some elements had not yet been discovered, so he left spaces for them. He also predicted what properties these undiscovered elements would have. later on, the elements that would fit in those spaces were discovered, and their properties matched what he predicted. some discrepancies existed (iodine and tellurium).

5. Moseley, Henry—1911—used Mendeleev’s PT to write the periodic law. periodic law: the physical and chemical properties of the elements are periodic functions of their atomic numbers. he arranged elements in order of atomic number, not weight. Today’s PT is arranged by atomic number, thanks to Moseley. Part II: Groups of the PT on the PT, a horizontal row is called a period, and a vertical column is a group. sometimes, other parts (other than single columns) are referred to as “groups.” each group of the PT shares similar chemical and physical properties. intensity of these properties tends to increase down a group. Moseley

6. each group of the PT shares similar chemical and physical properties. intensity of these properties tends to increase down a group. H

7. alkali metals = very reactive with most substances, especially water and air. Form oxides easily, have a silvery appearance. Soft in pure form —can be cut with knife. Stored under kerosene. (EC ends in s 1 ) HNa Na reacting with H 2 O

8. alkaline-earth metals = not as reactive as alkali metals. Harder, denser, and stronger. Have higher melting points. (EC ends in s 2 ) H Mg Ba in oil

9. transition metals = good conductors of electricity and heat. High luster. Less reactive than first 2 groups. Some exist as free elements (Pd, Pt, Au, Cu, Ag). Ductile (can be pulled into a wire), malleable (can be hammered, rolled into thin sheets) (EC ends in d 1-10 ) H Mn Cu

10. The p-block is divided into three types of elements: p-block metals: elements below the metalloid line. Very similar to the s- and d-block metals. nonmetals: elements above the metalloid line. Are brittle, non-conductors, some gases (includes H) H Ga P

11. metalloids: on the metalloid line = B, Si, Ge, As, Sb, Te. Have properties of metals and nonmetals. Semiconductors. halogens = highly reactive nonmetals. React with metals to form salts. Used in halogen lighting. (EC ends in s 2 p 5 ) H Si I

12. noble gases: unreactive. Very rarely form compounds with any element. Used in neon signs. lanthanides = top row of f-block. Very similar in chemical properties. Mostly natural. (EC ends in 6s 2 4f 1-14 ). actinides = bottom row of f-block. Very similar in chemical properties. Mostly synthetic. Some used in nuclear chemistry. (EC ends in 7s 2 5f 1-14 ). H Xe Nd U