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Chapter 4 Compounds and Their Bonds

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1 Chapter 4 Compounds and Their Bonds
4.1 Valence Electrons 4.2 Octet Rule and Ions LecturePLUS Timberlake

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Chemical Bonds Attraction between two or more atoms Interaction between valence electrons Ionic bonds Covalent bonds LecturePLUS Timberlake

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Valence Electrons Electrons in the highest (outer) electron level Have most contact with other atoms Known as valence electrons Outer shells of noble gases contain 8 valence electrons (except He = 2) Example: Ne 2, 8 Ar 2, 8, 8 LecturePLUS Timberlake

4 Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell electrons 1A A 3A A A A 7A A H He:            Li Be  B   C   N   O  : F  :Ne :                    Na Mg  Al  Si  P S :Cl  :Ar :         LecturePLUS Timberlake

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Learning Check A. X would be the electron dot formula for 1) Na 2) K 3) Al   B  X  would be the electron dot formula 1) B 2) N 3) P LecturePLUS Timberlake

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Solution A. X would be the electron dot formula for 1) Na 2) K   B  X  would be the electron dot formula 2) N 3) P LecturePLUS Timberlake

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Octet Rule An octet in the outer shell makes atoms stable Electrons are lost, gained or shared to form an octet Unpaired valence electrons strongly influence bonding LecturePLUS Timberlake

8 Formation of Ions from Metals
Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions form when the number of electrons are less than the number of protons Group 1A metals  ion 1+ Group 2A metals  ion 2+ Group 3A metals  ion 3+ LecturePLUS Timberlake

9 Formation of Sodium Ion
Sodium atom Sodium ion Na  – e  Na + ( = Ne) 11 p p+ 11 e e- LecturePLUS Timberlake

10 Formation of Magnesium Ion
Magnesium atom Magnesium ion Mg  – 2e  Mg2+ (=Ne) 12 p p+ 12 e e- LecturePLUS Timberlake

11 Some Typical Ions with Positive Charges (Cations)
Group 1A Group 2A Group 3A H+ Mg2+ Al3+ Li+ Ca2+ Na+ Sr2+ K+ Ba2+ LecturePLUS Timberlake

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Learning Check A. Number of valence electrons in aluminum 1) 1 e ) 2 e- 3) 3 e- B. Change in electrons for octet 1) lose 3e ) gain 3 e ) gain 5 e- C. Ionic charge of aluminum 1) ) ) 3+ LecturePLUS Timberlake

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Solution A. Number of valence electrons in aluminum 3) 3 e- B. Change in electrons for octet 1) lose 3e- C. Ionic charge of aluminum 3) 3+ LecturePLUS Timberlake

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Learning Check Give the ionic charge for each of the following: A. 12 p+ and 10 e- 1) 0 2) 2+ 3) 2- B. 50p+ and 46 e- 1) 2+ 2) 4+ 3) 4- C. 15 p+ and 18e- 2) ) 3- 3) 5- LecturePLUS Timberlake

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Solution Give the ionic charge for each of the following: A. 12 p+ and 10 e- 2) 2+ B. 50p+ and 46 e- 2) 4+ C. 15 p+ and 18e- 2) 3- LecturePLUS Timberlake

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Learning Check A. Why does Ca form a Ca2+ ion? B. Why does O form O2- ion? LecturePLUS Timberlake

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Solution A. Why does Ca form a Ca2+ ion? Loses 2 electrons to give octet (like Ar) B. Why does O form O2- ion? Gains 2 electrons to give octet e (like Ne) LecturePLUS Timberlake

18 Ions from Nonmetal Ions
In ionic compounds, nonmetals in 5A, 6A, and 7A gain electrons from metals Nonmetal add electrons to achieve the octet arrangement Nonmetal ionic charge: 3-, 2-, or 1- LecturePLUS Timberlake

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Fluoride Ion unpaired electron octet     : F  e : F :     (= Ne) 9 p p+ 9 e e- ionic charge LecturePLUS Timberlake

20 LecturePLUS Timberlake
Learning Check Complete the names of the following ions: 5A A A N3 O2 F nitride __________ fluoride P3 S2 Cl ___________ __________ _________ Br  _________ LecturePLUS Timberlake

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Solution 5A A A N3 O2 F nitride oxide fluoride P3 S2 Cl phosphide sulfide chloride Br  bromide LecturePLUS Timberlake


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