Answers for the work sheets

ELECTRONEGATIVITY AND POLARITY

Section 9.5

1. What is the meaning of the electronegativity?
The tendency of an atom to attract highest electronegativity electrons

2.Which element has the? What is the numerical value? What are the name and group number of the chemical family that has the highest overall electronegativity?
Fluorine; F; 3.98; halogens; group 7A

3. Which element has the lowest electronegativity? What is the numerical value? What are the name and group number of the chemical family that has the lowest overall electronegativity
Francine; 0.7; alkaline metals; group 1A

4. What general tend in electronegativity do you note going down a group? Across a period?
Decreasing – increasing

5. How are the electronegativity values used to determine the type of bond that exists between two atoms?
Electrons are subtracted.

6. Ionic compounds are usually soluble in polar substances- True

7. In a covalent molecular compound, the attraction between molecules tends to be strong- False

8. Unequal sharing of electrons between two bonded atoms always indicates
c. A polar covalent bond

9. When electronegativity of two bonded atoms differ greatly, the bond is
d. ionic

10. What is the electronegativity difference that usually is the dividing line between covalent and ionic bonds
b. 1.7

11. The Symbol δ is placed next to which of the following
a. The less electronegativity atom in a polar covalent bond

12. A nonpolar covalent bond is one in which
c. Electrons are shared equally.

13. Molecules containing only polar covalent bonds
b. May or May not be polar

14. What factor other than electronegativity determines whether a molecule as a whole is polar or not?
b. its geometry

15. Which of the following correctly describes the compound water, H₂O?
d. Polar overall, which polar covalent bonds

16. Which of the following correctly describes the compound carbon tetrachloride, CCl₄?
a. Nonpolar overall, with polar covalent bonds

17. A molecule of ammonia, NH₃, is
d. polar because there is an electronegativity difference and the molecule is trigonal pyramidal.

Periodic table trends and handout explanation

Sean here sorry for the late post, took me a while to figure out my password, anyway for thoses who missed what was done today we discussed the electronegativity of elements or if you will their ability to attract electrons by way of chemical bonding. I suggest you take out out your table of electronegativity, that would be that sheet package you got earlier in the year. As you can see fluorine has a electronegativity of 4.10 making it the most electronegative element on the table, if you do not see this you might have the wrong sheet. For those who missed today/yesterday's class take out one of the blank periodic tables received today, each element will have a subshell as seen in the electron configuration sheet (the one with the arrows in the boxes) this being said every element in groups I and II will have subshell on the outside with the exception of hydrogen and helium who are labeled as 2S. So if you want you can colour in the S, D,P and F sections, for instance as said before I and II should be labeled as S so fill in those columns along with 3 to 12 as D , 13 to 18 as P and finally the lanthanides and actinides (the bottom ones) as F, the colours you have to use won't matter as long as you can distinguish between them. Now for the second blank sheet you will need to point out a series of things. Now as we move from left to right on the electronegativites table we find that obviously the electronegativity is increasing so on the blank table draw an arrow pointing right and label it as eletronegativity increasing, the eletronegativity also decreases as you go down a group so you can label that. Now we go onto ionization energy AKA the energy needed for a element to take an electron from a gaseous atom. I won't go into a deep discussion about this so remember high ionization energy equal low possibility to form a positive ion and a low one means it will lose its outer electron with ease, so left to right on the table again draw a arrow pointing right and write ionization energy increases, this goes like the electronegativity going down a group, so arrow down ionization decreases. This same increase goes for the negative ions also, so left to right increase in ions you get the point anyhow lastly we go to atomic radius, now what would this be, atomic radius is the distance between the atoms nucleus to its outer most stable orbital. The atomic radius can be found by cutting the distance between the nuclei with the nuclei of a similar atom in half. You might not be able to find the distance of two nuclei yourself, apparently it takes equipment which is just out of the common student's hands to find said distance. Atomic radius is similar to ionic radius in the sense of distance between two things hence the radius part but ionic radius is the distance between cations and anions in crystal ions. Back to the table draw two arrows going down a group, one with atomic radius increasing and ionic radius increasing. Thus the table is pretty much done.

Reminder: test on wednesday
review: Do it, I guarantee it will not bite.
The scriber in line out of a random pick will be ...kayyy, due to user names of course it's random, good luck with the scribe and for those who haven't scribed the wait to be picked is worse than the actual scribe.