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3. Organizing the Elements periodic table- elements are arranged by increasing atomic number and by changes in physical and chemical properties. The Periodic Table 17.3

4. The Atom and the Periodic Table groups the vertical columns in the periodic table numbered 1 through 18. The Periodic Table Elements in each group have similar properties. 17.3

5. Electron Cloud Structure Most elements have a neutral charge ….the number of protons equals the electrons The Periodic Table Therefore, a carbon atom, with an atomic number of six, has six protons and six electrons. 17.3

6. Electron Cloud Structure The Periodic Table 17.3

7. Electron Cloud Structure Elements in the same group have the same number of electrons in their outer energy level. The Periodic Table The number of electrons in the outer energy level determines the chemical properties of the element. 17.3

8. Rows on the Table The Periodic Table 17.3

9. Rows on the Table Each new row on the table starts a new energy level The Periodic Table 17.3

10. Electron Dot Diagrams electron dot diagram uses the symbol of the element and dots to represent the electrons in the outer energy level. The Periodic Table Shows how the electrons are bonded when elements combine. 17.3

11. Same Group—Similar Properties The elements in Group 17, the halogens, have electron dot diagrams similar to chlorine. The Periodic Table All halogens have seven electrons in their outer energy levels. 17.3

12. Same Group—Similar Properties A common property of the halogens is the ability to form compounds readily with elements in Group 1. The Periodic Table Sodium has 1 electron in its outer shell Chlorine has 7 electrons in its outer shell = 8 Electron shell is full so its happy and forms NaCl— ordinary table salt. 17.3

13. Same Group—Similar Properties Not all elements will combine with other elements. (Complete energy Level) The Periodic Table The elements in Group 18 have complete outer energy levels. This special configuration makes Group 18 elements relatively unreactive. 17.3

14. Regions on the Periodic Table The periodic table has several regions with specific names. The Periodic Table periods - horizontal rows of elements on the periodic table Elements increase by one proton and one electron as you go from left to right 17.3

15. Regions on the Periodic Table All of the elements in the blue squares are metals. The Periodic Table 17.3

16. Regions on the Periodic Table The Periodic Table Those elements on the right side of the periodic table, in yellow, are classified as nonmetals. 17.3

17. Regions on the Periodic Table The Periodic Table The elements in green are metalloids or semimetals. 17.3

18. Section Check 17.3 Question 1 How are the elements arranged in the periodic table?

19. Section Check 17.3 Answer The elements are arranged by increasing atomic number and by changes in physical and chemical properties.

20. Section Check 17.3 Question 2 What do the elements in a vertical column of the periodic table have in common?

21. Answer 17.3 Section Check The vertical columns in the periodic table are called groups; elements in the same group have similar properties, such as electrical conductivity.

22. Section Check 17.3 Question 3 What do the dots in this electron dot diagram represent?

23. Section Check 17.3 Answer The dots represent the electrons in the outer energy level.

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25. End of Chapter Summary File