CHEMICAL KINETICS

CHEMICAL KINETICS

Today we spend the time going over the answers of the homework(pg.424-425;Q's.17-23), and the answers should be on the blog.

Then we had a new lesson; and here are the sheets:

This is Kinetis Assignment #1 which is homework:

PERIODIC TRENDS

On Tuesday we spent time going over the work sheets, or test review- and here are the answers.

Section 6.3

1. Atomic radii cannot be measured directly because the electron cloud surrounding the nucleus does not have a clearly defined
c. Outer edge

2. Which diagram best represents the group and period trends in atomic radii in the periodic table?
c. diagram c

3. The general trend in the radius of an atom moving down a group is partially accounted for by the
d. Shielding of the outer electrons by inner electrons.

4. A------ is an atom, or bonded group of atoms, that has a positive or negative charge.
b. Ion

5. An atom becomes negatively charged by
a. Gaining an electron

6. Which diagram best represents the relationship between the diameter of a sodium atom and the diameter of a positive sodium ion?
a. Diagram a

7. What is ionization energy?
Energy required to remove an electron from a gaseous form

8. Explain why an atom with a high ionization-energy value is not likely to form a positive ion?
A high ionization-energy value indicates that the atom has a strong hold on it’s electron and is not likely to lost an outer electron and form a positive ion

9. What is the period trend in the first ionization energies? Why?
The 1st ionization energies generally increases as you move left to right across a period. The increased nuclear change of each successive element produces and increased hold on the valence electrons.

10. What is the group trend in the first ionization energies? Why?
The 1st ionization energies generally decrease as you move down a group because atomic size increases down a graph, the valence electrons are far then from the nucleus and there for less strongly attached to the nucleus as a result, less energy is required to remove the valence electron.

11. State the Octet rule.
Atoms tend to gain, lose, or share electron to a quire a full set of eight valence electron.

12. What does the electro negativity of an element indicate?
Its atom’s ability to attract electron in a chemical bond
13. What are the period and group trends in electronegativities?
Increases left to right across a period and decreased as you move down a group.

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.