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1. Count the total number of valence electrons present. Remember number that an

ID: 1043977 • Letter: 1

Question

1. Count the total number of valence electrons present. Remember number that an element's group (1-8) gives the number of valence electrons it contributes to the total number. For polyatomic ions: add electrons to the total number to account for negative charges subtract electrons from the total number to account for positive charges. Step CH CCI4 H20 CN- 2. Draw the skeletal structure. From the molecular formula, draw the skeletal structure of the compound, using chemical symbols and placing bonded atoms next to one another. In general, the least electronegative atom will be the central atom (H cannot be a central atom because it only forms one covalent bond). Draw a single covalent bond (dash) between the central atom and each of the surrounding atoms. Step CH CCI4 H2O CN- 3. Subtract two electrons for each bond. For each bond (dash) in the skeletal structure, subtract two electrons (determined in step 1) to determine the number of remaining electrons. To determine the number of electron pairs, divide the number of remaining electrons by two. Step CH4 H20 CN- 4. Distribute remaining electrons. Use the remaining electrons to complete the octets of the terminal atoms (those bonded to the central atom) by placing pairs of electrons on each atom. (Remember that an H atom only requires two electrons to complete its valence shell). If there is more than one type of terminal atom, complete the octets of the most electronegative first. Step CHa CCl4 H20 O2 CN

Explanation / Answer

Answer 1.

a) Methane has = 0 valence electrons.

b) CCl4= 6*4 = 24 valence electrons.

c) Water = 4 valence electrons.

d) O2= 4*2= 8

e) CN- = 4.