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Covalent compounds

Covalent compounds. A covalent compound consists of two or more nonmetals . They are able to bond together by sharing their valence electrons. Covalent compounds. Atoms will share 1, 2, or 3 pairs of electrons so that each valence level has a stable octet .

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Covalent compounds

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  1. Covalent compounds A covalent compound consists of two or more nonmetals. They are able to bond together by sharing their valence electrons.

  2. Covalent compounds Atoms will share 1, 2, or 3 pairs of electrons so that each valence level has a stable octet. This sharing of electrons is the bond that keeps the atoms together.

  3. Covalent compounds Single covalent bond – Atoms share 1 pair of electrons. Double covalent bond – Atoms share 2 pairs of electrons. Triple covalent bond – Atoms share 3 pairs of electrons.

  4. Covalent compounds We can determine how many pairs of electrons are shared by drawing an Electron-Dot Diagram.

  5. Covalent compounds Steps for drawing Electron-Dot Diagrams; 1.) Add up the number of valence electrons that each atom brings to the compound. 2.) Arrange the atoms in the compound next to each other. If there are more than two atoms in the compound, arrange them symetrically with the atom that was listed first as the central atom. 3.) Place 1 pair of electrons between each atom that will be bonded together.

  6. Covalent compounds Steps for drawing Electron-Dot Diagrams (cont.); 4.) Use the remaining electrons to satify the octet rule for each element in the compound. 5.) If there are not enough electrons, place another pair of electrons between 2 atoms. 6.) If there are extra electrons, place them on the central atom, even if it already has 8 electrons.

  7. Covalent compounds Electron-Dot Diagrams; Draw the EDD for chlorine gas (Cl2). Each atom brings 7 valence electrons for a total of 14 electrons. Bond the chorine atoms with a single pair of electrons. Now there are 12 electrons left. Cl:Cl

  8. Covalent compounds Electron-Dot Diagrams; Place 6 more electrons around each chlorine atom. The Octet Rule is satisfied for both atoms. Cl:Cl

  9. Covalent compounds Electron-Dot Diagrams; Draw the EDD for bromine (Br2).

  10. Covalent compounds Electron-Dot Diagrams; Draw the EDD for carbon tetrachlorde (CCl4).

  11. Covalent compounds Electron-Dot Diagrams; Draw the EDD for Oxygen gas (O2).

  12. Covalent compounds Electron-Dot Diagrams; Draw the EDD for Nitrogen gas (N2).

  13. Covalent compounds Electron-Dot Diagrams; Draw the EDD for Carbon monoxide (CO).

  14. Covalent compounds Electron-Dot Diagrams; Draw the EDD for carbon dioxide (CO2).

  15. Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Just like everything else in Chemistry, there are exceptions to the Octet Rule. Hydrogen – Stable with only 2 valence electrons. Boron – Stable with 6 valence electrons. Sulfur and Phosphorous – Stable with 8, 10, or 12 valence electrons.

  16. Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of Hydrogen Chloride (HCl).

  17. Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of boron trifluoride (BF3).

  18. Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of phophorouspentachloride (PCl5).

  19. Covalent compounds Draw the electron dot diagram for the ammonium ion.

  20. Covalent compounds Resonant Structures Resonant structures are multiple ways of drawing an EDD for a molecule. The nitrate ion, NO3-1, has three different ways to draw its dot diagram;

  21. Covalent compounds Resonant Structures Which molecule has resosnant structures, SO3 or SO3-2?

  22. Covalent compounds Coodinate Covalent Bonds A coordinate covalent bond forms when one atom donates both electrons that are used to form a covalent bond.

  23. Covalent Compounds • Naming Covalent Compounds • Prefixes have to be used since different compounds can have different ratios of the same elements. mono = 1, di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa = 8, nona = 9, and deca = 10

  24. Covalent Compounds • Naming Covalent Compounds • Use a prefix to indicate the number of atoms of each element in the covalent compound and add the suffix ‘ide’ to the name of the last element. • N2O4 = dinitrogen tetroxide • P2O10 = diphophorousdecoxide • CO2 = carbon dioxide * • CO = carbon monoxide * *If there is only one of the first element, don’t use a prefix. It is implied that there is only 1 atom in the compound.

  25. Covalent Compounds • Naming Covalent Compounds • Name these covalent compounds; • H2O • CCl4 • CS2 • CCl4 • S2O6

  26. Covalent Compounds • Naming Covalent Compounds • There is a special type of covalent compounds called acids. • An acid will always contain hydrogen. • The hydrogen will be listed first. • Acids have a different naming system.

  27. Covalent Compounds • Naming Covalent Compounds • Naming Acids that do not contain oxygen; • Use the prefix ‘hydro’ on the name of the second element with the suffix ‘ic’. • HCl = hydrochloric acid • HF = hydrofluoric acid • H2S = hydrosulfic acid • HBr = hydrobromic acid

  28. Covalent Compounds • Naming Covalent Compounds • Naming Acids that contain oxygen; • If the anion ends in ‘ate’, then use the suffix ‘ic’ on the name of the anion. • H2SO4 = sufuric acid • If the anion ends in ‘ite’, then use the suffix ‘ous’ on the name of the anion. • H2SO3 = sulfurous acid

  29. Covalent Compounds • Naming Covalent Compounds • Name these acids; • HI • HCl • H3PO4 • H2C2O4 • HC2H3O2

  30. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Bonding electrons and lone pairs of electrons will repel themselves so that they will separate by the maximum distance possible.

  31. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • The shape of a molecule is determined by these repulsive forces.

  32. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Linear Shape • A molecule consisting of just 2 atoms will always be linear. • A molecule with 3 atoms can be linear if there are no lone pairs of electrons on the central atom.

  33. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Bent Shape • A molecule that has 3 atoms but there is a lone pair(s) of electrons on the central atom.

  34. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Trigonal Planar Shape • A molecule that has 4 atoms with no lone pairs on the central atom.

  35. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Trigonal Pyramidal Shape • A molecule that has 4 atoms with a lone pair of electrons on the central atom.

  36. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • Tetrahedral Shape • A molecule that has 5 atoms with no lone pairs of electrons on the central atom.

  37. Covalent Compounds • VSEPR Theory • Valence Shell Electron Pair Repulsions • TrigonalBipyrimidal Shape • A molecule that has 5 atoms with no lone pairs of electrons on the central atom.

  38. Covalent Compounds • Bond Polarity • Polar – having two distinct ends. • Sometimes, there is an unequal sharing of the electrons that make up a covalent bond. As a result, the bonding electrons can spend more time with atom compared to the other one.

  39. Covalent Compounds • Bond Polarity • The atom with the higher electronegativity value will have the bonding electrons most of the time. • The atom with the higher electronegativity will have a partial negative charge (δ-).

  40. Covalent Compounds • Bond Polarity • The atom with the lower value of electronegativity will appear to have a positive charge (δ+).

  41. Covalent Compounds • Bond Polarity • If two bonding atoms have the same electronegativity, the bond will not appear to be polar.

  42. Covalent Compounds • Bond Polarity • When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. • CO2 is nonpolar. δ-δ+δ- O = C = O

  43. Covalent Compounds • Bond Polarity • When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. • CCl4 is nonpolar.

  44. Covalent Compounds • Bond Polarity • When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. • H2O is polar.

  45. Covalent Compounds • Bond Polarity • When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. • HCl is polar.

  46. Covalent Compounds • Bond Polarity • When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. • Is NH3 polar or nonpolar?

  47. Covalent Compounds • Bond Polarity • Electronegativity Table

  48. Covalent Compounds • Are the following compounds polar or non polar? • PH3: • SO3: • H2S: • I2: • CS2:

  49. Covalent Compounds • Intermolecular Forces • Forces of attraction between 2 or more other molecules in a substance.

  50. Covalent Compounds • Intermolecular Forces • 3 types: London Dispersion Forces (weakest), Dipole-Dipole, and Hydrogen Bonding (strongest).

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