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Monday November 7, 2011

Monday November 7, 2011. (Covalent Bonding; Naming Covalent Compounds). Bell Ringer Monday, 11-7-11. Using your Periodic Table and your ion charts, name these chemical compounds:. HNO 3. AlBr 3. HCl. CaCl 2. H 3 PO 4. HF. GaI 3. H 2 SO 4. Announcements.

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Monday November 7, 2011

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  1. MondayNovember 7, 2011 (Covalent Bonding; Naming Covalent Compounds)

  2. Bell RingerMonday, 11-7-11 Using your Periodic Table and your ion charts, name these chemical compounds: HNO3 AlBr3 HCl CaCl2 H3PO4 HF GaI3 H2SO4

  3. Announcements I will not be available today after school.

  4. Salts - + - + H Cl Na OH A salt is an ionic compound composed of a cation from a base and the anion from an acid. For example, table salt (NaCl) contains the anion from hydrochloric acid (HCl) and the cation from the base sodium hydroxide (NaOH.) Salts are named in the same way as other ionic compounds.

  5. Covalent Bonding It’s nice to share!

  6. Covalent Bondingand Molecular Compounds A molecule is a neutral group of atoms that are held together by covalent bonds. A molecule may consist of two or more atoms of the same element, or two or more different types of atoms. A molecular compound is a chemical compound whose simplest units are molecules.

  7. Covalent Bondingand Molecular Compounds H2O A chemical formula indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts. A molecular formula shows the types and numbers of atoms combined in a single molecule of a molecular compound. A diatomic molecule is a molecule containing only two atoms. NaCl CO2 O2

  8. Formation of a Covalent Bond As atoms approach each other, their charged particles begin to interact. Nuclei and clouds attract each other - potential energy decreases. • The two nuclei and the two e- clouds repel each other – potential energy increases. • At a given distance, the repulsion equals the attraction, energy potential is at its lowest, and the bond forms.

  9. Characteristics of a Covalent Bond Bond length is the distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms. Example) The bond length of H-H is 75 pm. At this length, the one electron of each atom is shared by both atoms.

  10. Characteristics of a Covalent Bond Bond energy is the energy required to break a chemical bond and form neutral, isolated atoms. Example) The bond energy to break H2 is 436 kJ. Sharing electrons allows each atom to experience the effect of the stable electron configuration of a Noble Gas. Keep in mind that bond lengths and bond energies vary with the types of atoms that have bonded.

  11. Bond Length and Bond Energy

  12. Multiple Covalent Bonds A covalent bond produced by the sharing of two pairs of electrons between two atoms is called a double bond.

  13. Multiple Covalent Bonds A covalent bond produced by the sharing of three pairs of electrons between two atoms is called a triple bond.

  14. Multiple Covalent Bonds Double and triple bonds are referred to as multiple bonds.

  15. Multiple Covalent Bonds Sample Problem Draw the Lewis structure of methanal (formaldehyde) CH2O

  16. Chemical Formulas For a molecular compound, the chemical formula revels the type and number of atoms of each element contained in a single molecule of the compound.

  17. Naming Binary Molecular Compounds • Molecular compounds are composed of individual covalently bonded units, or molecules. • The prefix system is an older nomenclature for naming molecular compounds. • A Greek prefix is used in front of substance names in the compound to indicate the number of units of that substance that are present.

  18. Practice Name the following covalent compounds: CCl4 CO2 H2O carbon dioxide dihydrogen monoxide carbon tetrachloride Write the chemical formulas for the following covalent compounds: tetraphosphorus decaoxide dinitrogen trioxide N2O3 P4O10

  19. Naming Binary Molecular Compounds • The less-electronegative element is given first and is given a prefix only if it contributes more than one atom to a molecule of the compound. • The second element is named by combining a prefix indicating the number of atoms contributed by the element, the root of the name of the second element, and the ending –ide, which usually indicates that a compound contains only two elements. • The o or a at the end of a prefix is usually dropped when the word following the prefix begins with another vowel – for example, monoxide or pentoxide.

  20. Naming Binary Molecular Compounds

  21. Naming Binary Molecular Compounds In general, the order of nonmetals in compound names and formulas is: C, P, N, H, S, I, Br, Cl, O, F

  22. Naming Binary Molecular Compounds Examples • What is the name of As2O5? • Diarsenicpentoxide • Write the formula for oxygen difluoride • OF2

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