REVIEW: Chapter 8 ‐ Covalent Bonding 1. Typically, how many bonds & lone pairs will each have when covalently bonding? a. Boron d. Iodine – 1 bond; 3 lone pairs b. Silicone – 4 bonds; 0 lone pairs e. Phosphorous – 3 bonds; 1 lone pair c. Hydrogen – 1 bond; 0 lone pairs f. Oxygen – 2 bonds; 2 lone pairs
2. Which elements do not follow the octet rule? __H__ & __He__ never follow the octet rule. 3. What type of bond will each combination of atoms form? a. F & N – 2 nonmetals, therefore covalent d. B & Cl – 2 nonmetals, therefore covalent b. Al & O – 1 metal/1 nonm., therefore ionic e. Ca & I – 1 metal/1 nonm., therefore ionic c. Na & S – 1 metal/1 nonm., therefore ionic f. Fe & Cu – 2 metals, therefore metallic 4. What is the difference between: a. Molecules & Compounds? Compounds can be made using all types of bonds (ionic, covalent or metallic), but molecules can only be made using covalent bonds b. Monatomic elements & Diatomic molecules ? Monatomic elements exist as single atoms; diatomic molecules are made up of two of the same Atom. Monatomic are the noble gases; diatomic are BrINClHOF c. Empirical formulas, & Molecular formulas? Molecular gives the actual number of atoms in the molecule; Empirical is reduced It is possible for the empirical to be the same as the molecular if the formula can’t be reduced d. Polar bonds & Non‐polar bonds? Both describe covalent bonds. In a polar bond the electrons are NOT shared equally; in a non‐polar bond electrons are shared equally 5. Classify each of the following as an atom or a molecule: a. Be, atom b. CO, molec. c. N2, molec. d. H2O,molec. e. Ne, atom
6. How many diatomic elements are there? __7__ List the diatomic elements: Br, I, N, Cl, H, O, F 7. How many monatomic elements are there? __6__ List them: He, Ne, Ar, Kr, Xe, Rn 8. Complete the table with differences between ionic & covalent compounds: Covalent Ionic Non‐metals Metal & non‐metal Bond strength… weaker stronger Melting point… Lower Higher Gas or liquid Solid Shared Gained/lost Type of element… State @ room temp… Electrons are… 9. Draw the structure of each covalent molecules. They may contain single, double, or triple bonds: See drawing posted in classroom 10. Would a bond between the following elements be polar or non‐polar? a. C & I – non‐polar, because they have the same electronegativity & they will share electrons equally b. Si & N – polar, b/c they have diff. electronegatity & nitrogen will ‘hog’ the electrons they are sharing c. H & H – non‐polar, b/c they’re the same atom & have the same electronegatity & will share e‐ equally
11. Draw each molecules; label the dipoles, if any; identify each molecule as polar or non‐polar See drawing posted in classroom a. PH3 – polar b/c bonds are not all opposite each other (the lone pair on P is throwing it off) b. CF4 ‐ nonpolar b/c all the bonds are equal and opposite of each other c. SiHF3 – polar b/c the bonds are not all equal (3 are to F, but 1 is to H) d. N2 – nonpolar b/c all the same atom, therefore they share the e‐ equally
e. ClCN – nonpolar, b/c the atoms are different but Cl & N have the same electronegativity, therefore they are equal and opposite each other
12. Write formulas for the following covalent compounds: a. hexaboron nonasilicide – B6Si9 d. triIodine octafluoride – I3F8 b. chlorine dioxide – ClO2 e. dicarbon monosulfide – C2S c. hydrogen diiodide – HI2 f. dinitrogen heptoxide – N2O7
13. Write the names for the following covalent compounds: a. P4S5 – tetraphosphorous pentasulfide d. NF7 – nitrogen heptaflouride b. SeF6 – selenium hexaflouride e. S3O9 – trisulfur nonaoxide c. B2Si7 – diboron heptasilicide f. Si4O8 – tetrasilicon octaoxide 14. Arrange the following bonds from least (1) to most (6) polar: *The bigger the difference in polarity of the atoms, the more polar the bond is
4 H‐Cl (2.1) – (3.0), difference of .9 1 H‐H (2.1) – (2.1), difference of 0 5 H‐O (2.1) – (3.5), difference of 1.4 6 H‐F (2.1) – (4.0), difference of 1.9 2 H‐C (2.1) – (2.5), difference of .4 3 S‐Cl (2.5) – (3.0), difference of .5