Chemical Bonding Study Guide: Pre-AP
Test Date: Wednesday, Feb. 1st
Name:____________________________________________________
1.
Write the electron configuration for each atom below and circle which ones are stable.
a. Fe
b. P3c. Ar
d. Cs1+
[Ar]4s23d6-not stable
[Ne]3s23p6-stable
[Ne] 3s23p6-stable
[Xe]6s2-not stable
2. Circle the atoms below that are stable.
a. Cu
b. Zn2+
c. Ne
d. F1+
e. Pb2+
f. S2Not stable stable
stable
not stable stable
stable
3. What is the Octet Rule? Elements that are not naturally stable will become stable by gaining
(anions), losing (cations), or sharing valence electrons. (Most elements outer s and p-orbitals
filled).
4. What is an oxidation number? The charge on an atom when it becomes stable.
5. Why are compounds more common in nature than elements? Elements within a compound are
more stable than when they exist as an element.
6. Determine if the following are monatomic or polyatomic ions.
a. (OH)b. Clc. sulfate ion
d. sulfide ion
Poly
mono
poly(-ate ending)
mono (-ide ending)
7. Why are ionic compounds neutral? Because the ions making up the compound combine in such
a ratio that the overall charge on the compound is zero.
8. What is a molecule? A compound that consists of only non-metals = covalent compound
9. Draw the Lewis dot transfer between Ca and P. When you draw the Lewis Dot structure you
should get the following ratio of ions: Ca2P3
10. Determine which compounds below are ionic and which are covalent , and then give the
chemical name of each.
a. CCl4 : covalent, carbon tetrachloride
b. Fe(OH)3 : ionic, iron (III) hydroxide
c. SrS : ionic: strontium sulfide
d. N2 : covalent; nitrogen
e. PCl5 : covalent phosphorus pentachloride
f. Ca3P2 : ionic; calcium phosphide
11. Determine which compounds below are ionic and which are covalent, and give the chemical
formula of each.
a. oxygen disulfide: covalent: OS2
b. beryillium nitride: ionic; Be3N2
c. hydrogen: covalent; H2
d. Chromium (III) nitrate : ionic Cr(NO3)3
12. Circle the ionic compounds below that would occur in nature. (would form to reach stability)
a. magnesium phosphide
b. copper (II) calcide
could occur in nature
could not(2 metals)
c. FeAr
could not (noble gas)
d. V(PO4)
could occur in nature
13. a. What is a diatomic molecule? Usually two atoms of the same element.
b. What are the seven diatomic molecules?
H2, N2, O2, F2, Cl2, Br2, I2
14. What is electronegativity? The degree of attraction one element has for another element’s valence
electrons.
15. Use the graph below to answer questions on electronegativity.
a. What is the trend (pattern) for electronegativity across a period? Increases, except noble gases
b. What is the trend (pattern) for electronegativity down a group? Decreases
c. Rank the following elements in increasing order based on electronegativity.
N, Ne, B, Li (same period) Ne, Li, B, N
d. According to the graph, would ionic compounds or covalent compounds have a larger
electronegativity difference? Ionic compounds, because the atoms consisting an ionic bond
have very large differences in electronegativity values: metal and a nonmetal, compared to
covalent compounds where they consists of non-metals with closer electronegativity values.
16. Complete the table below on covalent compounds.
*Cannot draw molecular structures via compouter, so if have question e-mail me or we can go over
it tomorrow after test.
Molecular
Formula
Electron Dot Sharing
Molecular Structure
P2
Bonding Orbitals
(Sigma, Pi, or both)
1 sigma
2 pi
Polar or Non-polar
Bonds
p-p: non-polar bond
(share equally)
4 sigma
C-F: polar bond
(share unequally)
3 sigma
N-H: polar bond
(share unequally)
2 sigma
2 pi
C-S: polar bond
(share unequally)
CF4
NH3
CS2
17. Use the table above to answer these questions:
a. Which molecules above have a: a. single bond: CF4, NH3
b. double bond : CS2
c. triple bond :P2
b.What is the molecular geometry and bond angle of each of the following molecules above.
P2: linear; :180 degrees
CF4: tetrahedral (4 bonds with no lone pairs on central atom); 109.5 degrees
NH3: trigonal pyramidal (3 bonds with one lone pair on centra atom); 109.5 degrees
CS2: linear (2 bonds with central atom having no lone pairs); 180 degrees.
c. Which molecules above are polar molecules? Polar molecule: a region with a partial (+) charge and a
region with a partial (-) charge.
NH3: assymetrical in shape, lone pair on central atom, force vectors (arrows) are all pointing toward
nitrogen, the most electronegative element.
d.Which molecules above are non-polar molecules?
P2: non-polar bonds because atom of the same element.
CF4: symmetrical shape; force vectors (arrows) point in opposite directions cancelling their forces, no
lone pair on central atom.
CS2: symmetrical in shape; force vectors(arrows) pointing in opposite directions canceling their forces;
no lone pairs on central atom.
18. a. Illustrate the difference between sigma and pi bonds.
b. Which one is weaker and why? Pi is weaker because the atomic orbitals overlap above and below
the plane of the nucleus instead of along the same plane as the nucleus as with sigma bonds. The
distance weakens the attractive forces between the atoms and paired electrons in pi bonds.
19. Why are there different molecular geometries for molecules with the same number of bonds?
Lone pairs on the central atoms also influence the geometry of the molecule. The presence of the lone
pairs on the central atom will decrease the angles between the bonds in order to minimize electron
repulsion. In so doing, different types of geometrical structures are created.
20. What is the difference between polar covalent compounds and ionic compounds?
Polar covalent: unequal sharing of paired valence electrons, causing partial charges between the atoms
Ionic compounds: transfer of valence electrons, causing full charges (cation and anion)
21. Circle the compound in each example below that makes the statement true.
a. Would NaF or CH4 conduct electricity when dissolved in water? Explain your answer.
An ionic compound would conduct electricity, so it will be NaF because it is an ionic compound.
b. Is LiBr or P2O5 crystal lattice more brittle when stress is applied to it? Explain your answer.
Ionic compound’s crystal lattice is more brittle because it is composed of charged ions that must be
aligned to minimize repulsion. If stress is applied and the crystal lattice of the ions is shifted where
repulsion force is greater the compound will break or crack. Therefore, LiBr is more brittle because it is
an ionic compound.
c. Would C6H12O6 or Na(HCO3) crystal lattice grow faster? Explain your answer.
From the lab, we observed that ionic compounds grew faster because they consist of charged ions that
are strongly attracted to one another. Since Na(HCO3) is ionic it will grow faster. Sugar, C6H12O6, is
composed of neutral compounds and therefore will not form the crystal structure as quick.
22. Identify and define the types of intermolecular forces that are responsible for holding a group of
covalent compounds together in a sample of matter.
Intemolecular forces: forces between or that hold molecules together in a sample of matter.
Dispersion Forces: Temporary dipole forces due to random electron movement in the atoms making up
the molecules. The temporary dipoles can fluctuate back and forth depending on the constant motion
of the electrons. Since all molecules have mobile electrons, both polar and non-polar molecules can
have dispersion forces They are also the weakest since they are temporary dipole forces.
Dipole Forces: This only occurs with polar molecules. Polar molecules have partial charges, and it these
partial charges that attract molecules to one another (opposites attract).
Hydrogen Forces: Special type of dipole force where the molecules involved must have a hydrogen
atom that is covalently bonded to a very electronegative element (N, O, F). When this is present, the
strong partial charge on the Hydrogen can exhibit attraction (hydrogen bond) with a region of a
molecule with a strong partially negative charge. Hydrogen forces /bonds are the strongest type of
dipole forces.
23 . Label the following statements as either ionic or covalent.
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
Transfer of valence electrons to reach stability-Ionic
Prefixes are included with chemical name.-Covalent
–ate or –ite endings –Ionic (polyatomic ions)
Crystal lattice composed of ions: Ionic
Sharing of valence electrons to reach stability: Covalent
Roman numerals might be included with chemical name: Ionic (metals with multiple charges)
Crystal lattice composed of neutral atoms: Covalent
Compounds composed of non-metals only: Covalent
Compounds that have higher melting points: Ionic
Compounds that cannot conduct electricity when dissolved in water.: Covalent
Compounds that are composed of usually a metal and a non-metal.: Ionic
Compounds that can conduct electricity when dissolved in water. : Ionic