Study Guide for PS-B #1
KEY
Name:____________________________________________________________________ per_____
Be able to define:
 Ion- a charged particle made when an atom loses or gains electrons to get a full outer shell
 Isotope- atoms with different atomic masses because they have a different number of neutrons
 Covalent Bond- bond between two nonmetals in which electrons are shared
 Ionic Bond- bond btwn a metal and a non in which electrons are transferred and ions are made
 Metallic Bond- bond btwn two metals
1. An atom has 8 protons and 10 electrons. Write the chemical symbol for this ion. Be sure to indicate the
proper charge.
O
2-
2. Why are Lewis Dot structures more useful than Bohr models when predicting bonding?
Lewis dot structures help us focus on the VALENCE electron. Since these are the electrons are the ones
involved in bonding, it helps us predict if they will form ions and how they will react with other atoms.
Bohr models are misleading because they do not show the actual valence shell.
3. Predict the ion that will form for each of the following. Draw the lewis dot structure to help you.
a. Fluorine
F1-
b.Oxygen
O2-
Mg+2
c. Magnesium
4. How many atoms of each element are present in the following molecules?
a. H2O
2 Hydrogen, 1 Oxygen
b. CaCl2 1 Calcium, 2 Chlorine
c. C6H12O6
5.
6 Carbon, 12 Hydrogen, 6 Oxygen
Circle the correct words to complete the sentences.
a. A cation is formed when an atom (loses/gains) electrons to have a (positive/negative) charge.
b. When an atom gains electrons, it gets more (positive/negative).
c. When an atoms gains electrons, it becomes an (ion/isotope).
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6. State the octet rule. Why does it not apply to Helium?
Atoms want to have 8 valence electrons (8 electrons in their outer shell)
because most atoms will have a full outer shell with 8.
The octet rule works for most atoms
Helium only fills the first shell and 2 electrons makes it “full”…so He only needs 2 electrons to be nonreactive.
7. How many protons, neutrons and electrons are in the following:
a. C-14
p=__6___
n=___8___ e=__6____
b. C-12
p=__6___
n=___6____ e=___6___
c. O 2-
p=__8___
n=___?____ e=___10___
8. What is the “rule of thumb” when determining if atoms will form an ionic or covalent bond?
Metal with a Metal metallic
Metal with a NONmetal ionic
NONmetal with a NONmetal covalent
9. What kind of bond will form for each of the following compounds:
Metals/Nonmetals
Electronegativity diff
Molecule
Type of bond
(ionic, metallic, nonpolar covalent, or
polar covalent)
HCl
Non/Non
2.1-4=1.9
Polar covalent
Cu2
Metal/Metal
1.9-1.9=0
Metallic
MgO
Metal/Non
1.2-3.5=2.3
Ionic
NO2
Non/Non
3-4=1
Polar covalent
H2O
Non/Non
2.1-3.5=1.4
Polar covalent
CaCl2
Metal/Non
1-3=2
Ionic
NaCl
Metal/Non
.9-3=2.1
Ionic
O2
Non/Non
3.5-3.5=0
Nonpolar covalent
Remember…
Electronegativity difference of:
Greater than 1.7= ionic
Between .4 and 1.6= polar covalent
0-0.3= nonpolar covalent
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Determine whether the following molecules will have ionic or covalent bonds, draw the appropriate Lewis
structure, and name the compound (or write the formula)
1. CH4
H
Ionic or Covalent
Lewis
H
C
H
H
Chemical name: Carbon tetrahydride
2. Sodium Oxide
Ionic or Covalent
Lewis
[Na+]2[ O 2-]
Chemical Formula: Na2O
3.
Phosphorus Trichloride
Ionic or Covalent
Lewis
Chemical formula: PCl3
3
4. BaCl2
Ionic or Covalent
Lewis
[Ba+2][ Cl -]2
Chemical name: Barium Chloride
Name the following compounds:
1. P2O5 (covalent) Diphosphorus pentoxide
2. SrO (ionic) Strontium oxide
3. SiF4 (covalent) Silicon tetrafluoride
4. CO (covalent) Carbon monoxide
5. KCl (ionic) Potassium chloride
Write the following formulas:
1.
Magnesium Oxide
2.
Carbon dioxide
MgO
CO2
3. Dinitrogen trioxide N2O3
4. Francium Sulfide Fr2S
5. Barium Iodide BaI2
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