1. Periodic Table:

2. 1834- 1907 Russian Scientist

3. Dimitri Mendeleev: Mendeleev was the first to relate the elements in a systematic logical way. He listed them by order of increasing atomic mass

4. Peridic Table

5. Mendeleev: He also rearranged the columns so that the more similar elements were next to each other.

6. Periodic Table: An arrangement of the elements according to similarities in physical and chemical properties.

7. Henry Mosley 1887- 1915 British physicist Rearranged the periodic table

8. Henry Mosley Mosley arranged the table according to atomic number This is how we view the table today

9. Modern Periodic Table: Horizontal rows are called periods There are seven periods The number of elements ranges from 2 to 32

10. Periods The properties of the elements within a period change The pattern of properties within a period is repetitive

11. Periodic Law: When the elements are arranged in order of increasing atomic number, there is a repetition of physical and chemical properties.

12. Modern Periodic Table: Vertical columns are called groups Each group is identified by a number and a letter

13. Groups(two general categories) Identified by numbers and letters Group A- representative elements They exhibit a wide range of both physical and chemical properties

14. Representative elements: Divided into three groups: 1. Metals 2. Non metals 3. Metalloids

15. Types of metals: *Types of group A metals: 1. Alkali metals (group 1A) Li, Na, K, Rd, Cs, Fr 2. Alkaline earth metals (group 2A) Be, Mg, Ca, Sr, Ba, Ra

16. Other Metals: A variety of metals with varying chemical and physical properties.

17. Non- Metals: Elements such as Oxygen and Nitrogen are gases at room temperature Some non- metals such as sulfur are solids at room temperature and are very brittle One non- metal element, Bromine is liquid at room temperature

18. Halogens Group 7A non metals Include elements such as Fluorine, Chlorine and Iodine and Bromine

19. Noble Gases Elements that make up the last group of the periodic table Very stable elements that undergo few chemical reactions Inert gases Include, helium, neon, argon, krypton, xenon and radon

20. Groups continued: Group B Metals: represent the transition metals and inner transition metals

21. Metals: Properties of: 1. Have high electrical conductivity 2. Have a high luster 3. They are ductile: can be drawn into wires 4. They are malleable

22. Non- metals: Properties of: 1. Non- lustrous 2. Poor conductors of electricity

23. Non- metals: Some are gases; oxygen and chlorine Some are brittle solids; sulfur

24. Metalloids: Elements with properties that are intermediate between metals and nonmetals. Example; Silicon