1. The Periodic Table

2. Elements are arranged and identified on the periodic table by the number of protons they have in their nucleus. The ATOMIC NUMBER is equal to the number of protons in an element.

3. Quick ReviewQuick Review While the total number of electrons is important, it is even more important that you understand how many valence electrons an atom has. What are valence electrons?

4. Valence electrons are the electrons in the outer energy level. How many valence electrons do each of the following atoms have? 1 valence electron 2 valence electrons 3 valence electrons Quick ReviewQuick Review

5. Elements in the same column or group have similar physical and chemical properties. This because they all have the same number of valence electrons!

6. Reading Roman numerals: I = 1 II = 2 III = 3 IV = 4 V = 5 VI = 6 VII = 7 VIII = 8 How many valence electrons do the elements of group 2 have? II = 2 You will ignore the A’s and B’s.

7. How many valence electrons do the elements of group 17 have? VII = 7 How many valence electrons do the elements of group 14 have? IV = 4

8. How many valence electrons do the elements of group 16 have? VI = 6 How many valence electrons does phosphorous have? V = 5 Remember: We can determine the number of valence electrons in the atom of an element by using the Roman numerals on the periodic table.

9. Lewis Dot Diagrams: Lewis dot structures show the number of valence electrons in an atom using an atoms symbol surrounded by dots representing the valence electrons. Use the Roman numerals on your periodic table to determine the number of valence electrons for elements below. Decide which Lewis dot diagram is an accurate representation. Which Lewis Dot Diagram below accurately represents hydrogen? HHH

10. Which Lewis Dot Diagram below accurately represents nitrogen? NN N Which Lewis Dot Diagram below accurately represents carbon? CC C

11. Which Lewis Dot Diagram below accurately represents boron? BB B Which Lewis Dot Diagram below accurately represents phosphorous? PP P

12. There are several things you will need to memorize about the periodic table. Find the dark jagged line on the Periodic Table On the left side of this line are all of the metals On the right side of this line are all of the nonmetals

13. Chemical reactions occur when atoms gain, lose, or share electrons. Metals ________________ electrons. This always gives them a ____ charge. lose or donate + Nonmetals _________ electrons. This always gives them a ____ charge. gain _ Nonmetal can also share electrons with one another, and this is what makes a covalent compound.

14. You need to understand the pattern of elements gaining and losing electrons on the periodic table. donate 1 electron donate 2 electron gains 1 electrons Does NOT gain or lose gains 2 electrons Think about counting from the outside to the inside!

15. Metals lose or donate electrons and nonmetals gain electrons Because of this metals react with nonmetals! sodiumchlorinesodium chloride +1

16. sodiumchlorinesodium chloride +1 We can see that it is a 1:1 ratio between sodium and chlorine, but why does it work out that way? Once again, it has to do with the valence electrons! Since sodium donates 1 electron and chlorine gains 1 electron, they join together in a 1:1 ratio.

17. This is true for all of the combinations of Group 1 and Group 17 elements! HCl LiF NaBr KF CsI RbCl HBr KCl LiF RbBr KBr NaI LiCl FrCl HF They are all 1:1 ratios!

18. magnesiumsulfidemagnesium sulfide +2-2 This is also true between metals that lose 2 valence electrons and the nonmetals that gain 2 valence electrons. Since magnesium donates 2 electrons and sulfur gains 2 electrons, they join together in a 1:1 ratio.

19. This is true for all of the combinations of Group 2 and Group 16 elements! BeO MgS SrO BaSe CaTe CaS BeSe MgO SrS BaO MgSe CaO BeS BaTe SrSe They are all 1:1 ratios!

20. The Periodic Table can be used to determine the charge of all of the principal elements! +1 +2+3 +4 or -4 -3-2-1 0

21. The elements that lay on either side of the dark, jagged have rather unique properties. Sometimes they act like metals, and sometimes they act like nonmetals. Because of this, they are called Metalloids

22. The metals in the middle of the periodic table are known as the transition metals. Transition Metals

23. There are several groups on the periodic table whose name you should have memorized. Alkali Metals Alkaline Earth Metals Halogens Noble Gases Group 1 = Alkali Metals Group 2 = Alkaline Earth Metals Group 17 = Halogens Group 18 = Noble Gases

24. You also need to know that Iron, Cobalt, and Nickel have special properties such as the ability to be made into magnets. Together, these three elements are known as the. Iron Triad Iron Triad

25. Which group on the periodic table undergoes the fewest chemical reactions? Group 18 The Noble Gases They are inert gases. This is a chemical property that means they will not react with other substances. Inert means inactive!

26. Ionic compounds are ALWAYS between a metal and a nonmetal. On the left side of this line are all of the metals On the right side of this line are all of the nonmetals

27. Covalent compounds are ALWAYS between nonmetals. On the right side of this line are all of the nonmetals

28. Understanding the previous facts at a conceptual level is critical to your success in chemistry. Using this knowledge, determine the identity of each of the following unknown elements. The formula above shows the ratio of an unidentified element, X, to chlorine in a covalent molecule. Which element below is most likely the identity of Element X? A sodiumB neonC phosphorousD copper XCl 3 Since it is a covalent molecule, it has to be a nonmetal. It cannot be neon since neon is an inert noble gas that would not react with chlorine.

29. The formula above shows the ratio of an unidentified element, X, to sodium in an ionic salt. In which group on the periodic table does Element X most likely belong? A Group 1 B Group 2 C Group 17 D Group 18 NaX Since it is an ionic salt, it has to be a nonmetal since sodium is a metal. It cannot be group 18 since group 18 is the inert noble gases that would not react with sodium.

30. The formula above shows the ratio of an unidentified element, X, to fluorine in an ionic salt. Which group below is most likely the identity of Element X? A sulfur B lithium C arsenic D krypton XF Since it is an ionic salt, it has to be a metal since fluorine is a nonmetal.

31. The Law of Conservation of Mass

32. Scientist Mass of Reactant 1 Mass of Reactant 2 Mass of Product Scientist A19 g22 g42 g Scientist B19.4 g22.4 g41.7 g Scientist C19.36 g22.37 g41.74 g Scientist D19.364 g22.372 g41.736 g According to the Law of Conservation of Mass, the mass of the reactants should equal the mass of the products. Reactant 1 + Reactant 2 Product Which scientist’s results below best support the Law of Conservation of Mass?

33. Hydrogen + Oxygen Water 16.0 g 128 g ? g 16.0 grams of hydrogen reacts with 128 grams of oxygen. Assuming all of the reactants are used up, how much water will be produced? Solving for Mass When this concept is shown with a chemical equation, nothing changes about how it should be solved. 16.0 g + 128 g = 144 g