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Chemical Bonding and Nomenclature Feb 5, 2013

Chemical Bonding and Nomenclature Feb 5, 2013. BW : How is the octet rule related to covalent bonding? Pg 217. Obj : Use the octet rule to diagram molecules. Reflection: Diagram CH4 showing LLD and (covalent) bonding. Chemical Bonding (covalent).

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Chemical Bonding and Nomenclature Feb 5, 2013

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  1. Chemical Bonding and NomenclatureFeb 5, 2013 BW : How is the octet rule related to covalent bonding? Pg 217. Obj: Use the octet rule to diagram molecules Reflection: Diagram CH4 showing LLD and (covalent) bonding.

  2. Chemical Bonding (covalent) After reading page 217, Discuss at your table, (1) how the octet rule is similar when comparing ionic bonds, and covalent bonds. (2) What is different when using the octet rule in ionic bonds vs covalent bonds? Take 7 minutes to discuss at your table. Be able to answer the question (talk out). Be able to draw a diagram that illustrates the answer. (participation pts hand-out)

  3. Chemical Bonding and Nomenclature The ELECTRONEGATIVITY of an element is: the tendency of an atom to attract electrons.

  4. Chemical Bonding and Nomenclature Review Transition metals:

  5. Chemical Bonding and Nomenclature Review Transition metals:

  6. Chemical Bond  Electronegativity: the degree to which an element can bond. Draw a molecule, using circles for atoms Draw a compound, using circle for atoms draw a diatomic molecule Draw the molecular formula for C2H6 I want you to meet a friend of mine?

  7. Chemical Bond .When to use numbers before a compound.  2NaCl = 2 molecules of NaCl…? NaCl2 = 2 atoms of Cl Now, molecule is frequently used, however, the accurate way to word the above is, 2 ions of NaCl have formed an ionic compound.

  8. Chemical Bond Video. In drawing out; they appear 1. H—H Draw the bonding arrangement for Fluorine, a diatomic molecule; I want you to meet a friend of mine?

  9. Chemical Bond 5. Methane: CH4 6. BCl3 boron Trichloride 7. HCl = Hydrogen chloride YOU DO THESE 8. H202 DihydrogenDioxide 11. PCl3 Phosphorus Trichloride video http://www.youtube.com/watch?v=6_YhSLnAmVo electronegativity page…. polar http://www.youtube.com/watch?v=IBtCV12i2BQ Double and Triple Bonds….. atoms form double or triple bond if they can form noble gas configuration. 12. 02 Diatomic molecule - - - - > is a double bond. 13. N is a triple bond , also a diatomic molecule 14. C02 Carbon Dioxide is a double bond. 15. NF3 16. SB2 8.2c Exceptions to the Octet Rule Although many Lewis structures follow the octet rule, there are exceptions. Electron-deficient compounds are compounds in which an element has an incomplete octet. Some elements, notably H, Be, and B, often have fewer than eight electrons in Lewis structures. Hydrogen has a single valence electron in a 1s orbital and therefore accommodates only two electrons when it forms covalent bonds. Therefore, it almost always forms only one chemical bond to another atom and does not accommodate lone pairs of electrons. Beryllium (two valence electrons) and boron (three valence electrons) often accommodate only four or six electrons, respectively, in Lewis structures. For example, BF3 is an electron-deficient compound. Each fluorine has a complete octet (six nonbonding electrons plus two bonding electrons), but boron has only six electrons (six bonding electrons and no lone pairs). Changing a fluorine lone pair to a bonding pair would alleviate the electron deficiency, but fluorine's high electron affinity means this element is unlikely to share its nonbonding electrons with boron. The electron deficiency means that BF3 is a highly reactive compound. For example, it reacts readily with NH3. In this reaction, the lone pair on N forms a new covalent bond between the compounds. In the new compound, both N and B have full octets and the neither compound is electron deficient. Free radicals are compounds with at least one unpaired electron. Free radicals can also be electron-deficient compounds. Nitrogen monoxide (nitric oxide, NO) is a free-radical compound because it is an odd-electron molecule with 11 valence electrons and 1 unpaired electron. Notice that the unpaired electron is placed on the nitrogen atom. In general, the odd electron in free radicals is not located on oxygen because of its high electron affinity. Free radicals are highly reactive species because the unpaired electrons react with other molecules. Pure NO, for example, reacts readily with halogens, O2, and other free radicals. Elements with an expanded valence (also called an expanded octet) have more than 8 electrons (often 10 or 12) in a Lewis structure. Elements in the third period and below, such as phosphorus, sulfur, and bromine, often have an expanded valence because of their larger radii (when compared to the second-row elements) and the availability of empty d orbitals in the valence shell. Consider the Lewis structure of SF4. Each fluorine has a satisfied octet (6 nonbonding electrons plus 2 bonding electrons), but the central sulfur atom has an expanded octet with 10 electrons around it (8 bonding electrons and 2 nonbonding electrons). Example Problem: Draw Lewis Structures (Octet Rule Exceptions) Draw the Lewis structure for ClO IBr3 You are asked to draw the Lewis structure for a molecule or ion with a central atom that can have an expanded valence. You are given the chemical formula for a molecule or ion. Step 1: 7 + 6 = 13 valence electrons (or 6 pairs and 1 unpaired electron) Steps 2 and 3: Steps 4 and 5: This is an odd-electron molecule (a free radical). The unpaired electron is placed on chlorine because oxygen has a high electron affinity. Step 1: 7 + (3 × 7) = 28 valence electrons (or 14 pairs) Steps 2 and 3: Iodine has a lower affinity for electrons that bromine, so it is the central atom. Steps 4 and 5: Iodine is in the fifth period and therefore can have an expanded valence. exceptions to octet rule http://s-owl.cengage.com/ebooks/vining_owlbook_prototype/ebook/videos/VS_8_2_3.htm C02 octet = yes to obtain octet, C, needs to obtain 4 Oxygen needs 2 octet = yes S03 NEW Polyatomic ion configuration also can obtain octet … H30+ How? It can do this if H is an ion 3 + and 2 – ends up with a + charge 0H - Hydrogen ion BF4- S04 2- carbonate ion = C03 2- HC03- Double Bonds…. I want you to meet a friend of mine?

  10. Chemical Bond electronegativity page 238 Can you predict bonding type? (discuss in your table) Can you predict Covalent? Ionic? Polar covalent? (Or polar) polar http://www.youtube.com/watch?v=IBtCV12i2BQ I want you to meet a friend of mine?

  11. Chemical Bond 14. C02 Carbon Dioxide is a double bond. 15. NF3 16. SB2 8.2c Exceptions to the Octet Rule Although many Lewis structures follow the octet rule, there are exceptions. I want you to meet a friend of mine?

  12. Chemical Bond Therefore, it almost always forms only one chemical bond to another atom and does not accommodate lone pairs of electrons. Beryllium (two valence electrons) and boron (three valence electrons) often accommodate only four or six electrons, respectively, in Lewis structures. I want you to meet a friend of mine?

  13. Chemical Bond The electron deficiency means that BF3 is a highly reactive compound. For example, it reacts readily with NH3. In this reaction, the lone pair on N forms a new covalent bond between the compounds. In the new compound, both N and B have full octets and the neither compound is electron deficient. I want you to meet a friend of mine?

  14. Chemical Bond In general, the odd electron in free radicals is not located on oxygen because of its high electron affinity. Free radicals are highly reactive species because the unpaired electrons react with other molecules. Pure NO, for example, reacts readily with halogens, O2, and other free radicals. I want you to meet a friend of mine?

  15. Chemical Bond Consider the Lewis structure of SF4. Each fluorine has a satisfied octet (6 nonbonding electrons plus 2 bonding electrons), but the central sulfur atom has an expanded octet with 10 electrons around it (8 bonding electrons and 2 nonbonding electrons). Example Problem: Draw Lewis Structures (Octet Rule Exceptions) Draw the Lewis structure for ClO IBr3 You are asked to draw the Lewis structure for a molecule or ion with a central atom that can have an expanded valence. You are given the chemical formula for a molecule or ion. Step 1: 7 + 6 = 13 valence electrons (or 6 pairs and 1 unpaired electron) Steps 2 and 3: Steps 4 and 5: This is an odd-electron molecule (a free radical). The unpaired electron is placed on chlorine because oxygen has a high electron affinity. Step 1: 7 + (3 × 7) = 28 valence electrons (or 14 pairs) Steps 2 and 3: Iodine has a lower affinity for electrons that bromine, so it is the central atom. Steps 4 and 5: Iodine is in the fifth period and therefore can have an expanded valence. exceptions to octet rule http://s-owl.cengage.com/ebooks/vining_owlbook_prototype/ebook/videos/VS_8_2_3.htm C02 octet = yes to obtain octet, C, needs to obtain 4 Oxygen needs 2 octet = yes S03 NEW Polyatomic ion configuration also can obtain octet … H30+ How? It can do this if H is an ion 3 + and 2 – ends up with a + charge 0H - Hydrogen ion BF4- S04 2- carbonate ion = C03 2- HC03- Double Bonds…. I want you to meet a friend of mine?

  16. Chemical Bond You are asked to draw the Lewis structure for a molecule or ion with a central atom that can have an expanded valence. You are given the chemical formula for a molecule or ion. Step 1: 7 + 6 = 13 valence electrons (or 6 pairs and 1 unpaired electron) I want you to meet a friend of mine?

  17. Chemical Bond Step 1: 7 + (3 × 7) = 28 valence electrons (or 14 pairs) Steps 2 and 3: Iodine has a lower affinity for electrons that bromine, so it is the central atom. Steps 4 and 5: Iodine is in the fifth period and therefore can have an expanded valence. exceptions to octet rule http://s-owl.cengage.com/ebooks/vining_owlbook_prototype/ebook/videos/VS_8_2_3.htm C02 octet = yes to obtain octet, C, needs to obtain 4 Oxygen needs 2 octet = yes S03 NEW Polyatomic ion configuration also can obtain octet … H30+ How? It can do this if H is an ion 3 + and 2 – ends up with a + charge 0H - Hydrogen ion BF4- S04 2- carbonate ion = C03 2- HC03- Double Bonds…. I want you to meet a friend of mine?

  18. Chemical Bond Can you predict bonding? BW> What is van del wahls forces (pg 240) read and answer. I want you to meet a friend of mine?

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