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Explore the types of bonding in chemistry - ionic, covalent, polar - and learn about electron sharing, polarity, ion formation, and polyatomic ions.
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Section 12.1(A&B)Section 12.2 (All) Period 1 Group #1
Bonds • Ionic bonding-oppositely charged ions • Ionic compound-metal and nonmetal • Covalent bonding-electrons shared in nuclei • Polar covalent bond-unequal sharing of electrons • Stronger attractions for shared electrons Ex. Hydrogen Fluoride (HF) H – F S + S¯
Questions • Compare the three types of bonding. • The unequal sharing of electrons is due to what type of attraction between elements?
Electro-negativity • Unequal sharing between two atoms • Increases left to right across the periodic table • Decreases down a group • Polarity of a bond depends on the difference between electro-negativity • Higher electro-negativity means close electrons sharing values
Questions • How can you find the polarity of bonds? • Solve the polar bond of F- Au
Electron Configuration of Ions • Representative metals form ions by losing electrons to achieve configuration of previous noble gases • Ex. Mg→Mg² + 2e- (Ne) 3s² - 2e- • Nonmetals form ions by gaining electrons to achieve next noble gases • Ex. Br → Br- + 1+ (Kr) • Cation and anion have end results of noble gases
Questions • How do representative metals form ions to achieve electron configurations? • Solve Fluorine (Fe) to achieve configuration.
Ionic compounds • Ions packed specifically to maximize attraction • Described by a model with a closely packed ions as spheres • Cation loses all valence electrons – becomes smaller • Anion gains – becomes bigger
Model of Ionic Compound Cl- is the anion and Na+ is the cation
Review Questions • Why are cations smaller than an anions? • Explain why ions are formed in specific ways.
Polyatomic Ions • Compounds contain polyatomic ions • charged species of several atoms • Individual polyatomic ions held by covalent bonds • behave as unit • free movement when dissolved in water
Polyatomic Ion Example NH4+ → ammonium nitrate and NO3- ions
Quiz ?’s • Shared electrons determine what type of bond? • Which area of the periodic table has the most electro-negativity? • How are the configurations of metals and nonmetals different? • Describe the model depicting the ions’ attraction. • What is the relationship between compounds and polyatomic ions?
Answers • Covalent bonds • The upper right corner • Metals form electron configurations of the previous noble gas while nonmetals form those of the next noble gas. • Tightly packed (hard) spheres; small ions occupy gaps formed by larger ions • Compounds contain polyatomic ions.
References • http://library.tedankara.k12.tr/chemistry/vol1/molecule/trans55.jpg • http://www.chemistry.wustl.edu/~edudev/LabTutorials/PeriodicProperties/Ions/images/ammonium3a.jpg • http://mypchem.com/myp9/myp9c/myp9c_img/ionic_bonding5.gif