CHEMISTRY 1
STUDY GUIDE FOR UNIT 7 with Answers!!
CHEMICAL BONDING AND NOMENCLATURE
Guiding Questions:
1. How can the number of valence electrons in an element be found?
2. How can the periodic table be used to predict the type of bond that can be
made between two elements?
3. How is polarity related to bonding?
4. How are elements combined to make chemical formulas?
5. Why is it important that there is a consistent way to name chemical
compounds?
6. What information can be derived from the name of a compound?
7. How are ionic compounds different from covalent ones?
Key Vocabulary Terms (Chapters 8 and 9 in text):
Valence electrons
Oxidation number
Anion
Cation
Metallic bond
Law of Definite Proportion
polyatomic ion
hydrates
Electrolyte
Formula Unit
Oxyacid
Binary Compound
Covalent Bond
Ionic bond
Diatomic molecule
Chemical Bond
Oxyanion
1. State the Octet Rule.
Neutral atoms tend to gain or lose electrons in chemical reactions so
that they have 8 valence electrons.
2. What is a chemical bond?
A strong attachment of elements or ions to each other that makes all
species involved follow the octet rule is called a chemical bond.
3. What is the Law of Definite Proportion?
The electronegativity of an element indicates the relative ability of its atoms to
attract electrons in a chemical bond.
4. Distinguish between a covalent bond, and ionic bond, and a metallic
bond.
In a covalent bond, electrons are shared between two atoms. In an ionic
bond, electrons are transferred from a metal to a nonmetal. In metallic
bonding, atoms at the surface of a metal have valence electrons that
move freely around the whole sample—a sea of electrons.
5.
What type of bond do nonmetals generally form with other nonmetals?
Metals with nonmetals?
They form covalent molecules because their electronegativities are
similar. Metals with nonmetals form ionic bonds because metals are
willing to give up their electrons to nonmetals to reach an octet.
6. What type of bond produces a dipole? Describe what is meant by a
dipole for a molecule consisting of only two atoms.
Polar covalent bond in which the electronegativity is different for the
two nonmetals makes a dipole. That means the electrons are going to
be around the more electronegative element more often than the less
electronegative one, causing a charge difference at either end of the
molecule.
7. Draw a representation of a binary (two atom) molecule in which the
bonding is:
a. nonpolar covalent, b. polar covalent, and c. ionic bond
a.
b.
c.
8. Electronegativity difference can be used to determine bond type. What is
the rule for determining bond type from electronegativity?
1. If electronegativities are equal or almost (i.e. if the electronegativity
difference is 0-0.2), the bond is pure covalent.
2. If electronegativity difference between the two atoms is greater than 0.2,
but less than 1.7, the bond is polar covalent.
3. If electronegativity difference between the two atoms is 1.7, or greater,
the bond is ionic.
9. According to the general rules of electronegativites, what type of bond is
formed by each of the following pairs of elements?
a. potassium and chlorine
3.0 - .8 = 2.2 ionic
b. sulfur and sulfur
2.5 - 2.5= 0 pure covalent
c. carbon and bromine
2.5 – 2.8 = .3 polar covalent
d. zinc and oxygen
3.5 – 1.7 = 1.8 ionic
10. Predict what type of bond is likely to be formed between atoms of alkali
metals and atoms of halogens. What type of bond would most likely form
between halogens and the oxygen group elements (O, S, Se, Te, Po)?
Ionic bonds will form between alkali metals and halogens, covalent
bonds (polar or nonpolar) will form between halogens and oxygen
group elements.
11. Write the Lewis electron dot structure for elements 1-10.
12. Identify each of the following as an atom, molecule, or ion.
a. N2 molecule
b. Ne atom
c. Cu+2 ion
d. OH-1 polyatomic ion
e. Al atom
f. CO2 molecule
13. What is the process for naming a binary ionic compound or writing its
formula? Remember ionic compounds exchange electrons!
Naming
a. Write the name of the metal
b. Write the root of nonmetal + -ide suffix
Formulas
a. Write the symbols for each element and their charges from the
periodic table.
b. Crisscross the charges to get the subscripts.
c. Reduce to lowest terms
14. What is the process for naming or writing the formula for an ionic
compound that has polyatomic ions?
Naming
a. Write the name of the metal or polyatomic ion, use RN as needed.
b. Write the name of the negative polyatomic ion or nonmetal + -ide.
Formulas
a. Write the symbols for the positive ions and negative ions with their
charges.
b. Crisscross the charges for subscripts. If you need a subscript on
a polyatomic ion, put parentheses around it first.
c. Reduce the subscripts to lowest terms.
15. Copper forms two different compounds with chlorine, CuCl and CuCl2. In
writing their names, how do we distinguish them?
CuCl is copper(I) chloride and CuCl2 is copper(II) chloride
16. A polyatomic ion is a group of bonded atoms that acts as a single unit
with a net charge. For the eleven polyatomic ions listed below, give the
chemical formula and the charge. THESE MUST BE MEMORIZED!!
a. Ammonium, NH4 +1
g. Acetate, C2H3O2-1 or CH3COOH-1
b. Bicarbonate, HCO3-1
h. Carbonate, CO3-2
-1
c. Nitrite, NO2
i. Sulfite, SO3-2
d. Nitrate, NO3-1
j. Sulfate, SO4-2
-1
e. Hydroxide, OH
k. Phosphate, PO4-3
f. Cyanide, CN-1
17. What is the process for naming or writing the formula for an ionic
compound that has transition metals?
Transition metals vary in their charges, so the same element can have
many different charges. If the charge changes, the compound changes.
Naming
a. Write the name of the metal and its charge in Roman Numerals.
b. Write the name of the polyatomic ion, or the nonmetal + -ide.
Formulas
a. Write the symbols for the positive metal with its charge and the
nonmetal or polyatomic ion and its charge.
b. Crisscross the charges for subscripts. If you need a subscript on
a polyatomic ion, put parentheses around it first.
c. Reduce the subscripts to lowest terms.
18. What is the difference between Co3 and CO3 when written in a formula?
What is the difference between (OH)2 and OH2 in a chemical formula?
Co3 means that you have three atoms of cobalt. CO3 means that you
have a carbonate polyatomic ion made up of one carbon atom and
three oxygen atoms covalent bonded together.
19. Why is it necessary to use parentheses in writing the formula for calcium
nitrate?
Since calcium is a +2 and nitrate is -1, two nitrate ions are needed. If you
didn’t put the parentheses, you would have two subscripts. Ca(NO3)2 and
not CaNO32
20. What is the process for naming or writing the formula for a binary
covalent compound?
Naming
a. Write the name of the first nonmetal. Put a prefix on it if it has a
subscript.
b. Write a prefix for the second nonmetal + root of nonmetal + -ide.
Formulas
a. Write the symbols of each nonmetal.
b. Use the prefixes to determine the subscript. Never use charges!!
21. Name the following compounds:
a. NaCl
sodium chloride
b. SrCl2
strontium chloride
c. SF6
sulfur hexafluoride
d. Ca3(PO4)2
calcium phosphate
e. AuBr
gold (I) bromide
f.
beryllium nitride
Be3N2
g. Ag2S
silver sulfide
h. CO
carbon monoxide
22. Write formulas for the following compounds:
a. magnesium hydroxide
Mg(OH)2
b. silver acetate
AgC2H3O2
c. aluminum sulfate
Al2(SO4)3
d. tin(IV) chloride
SnCl4
e. calcium oxide
CaO
f. nickel(II) bromide
NiBr2
g. chromium(III) phosphate
CrPO4
h. dinitrogen pentoxide
N2O5
23. What is the process for naming or writing the formula for a binary acid?
Binary acids have hydrogen + a nonmetal.
Naming
i. Write hydro + root of second nonmetal + -ic acid.
Formulas
a. Write the symbols for hydrogen and the second nonmetal with their
charges.
b. Crisscross the charges to get hydrogen’s subscript.
24. What is the process for naming or writing the formula for an oxyacid?
Oxyacids have hydrogen + a polyatomic ion
Naming
a. Look at the polyatomic ion. If it ends with –ate, write the root of the
polyatomic ion name + -ic + acid.
b. If the polyatomic ion ends with –ite, write the root of the polyatomic
ion name + -ous + acid.
Formulas
a. Write the symbols for hydrogen and the polyatomic ion with their
charges.
b. Crisscross the charges for hydrogen’s subscript.
25. Provide the names or the formula for each of the following common
acids.
Name
Formula
a. acetic acid
b. __sulfuric acid_________
c. phosphoric acid
______HC2H3O2____
H2SO4
_____H3PO4______
d. _____Nitric Acid_______
HNO3
e. ___nitrous acid_________
HNO2
26. What are some physical characteristics of ionic vs. covalent
compounds?
Ionic
Covalent
Brittle crystals
Soft and sometimes flaky
High melting point
Low melting point
Conduct a current when dissolved—
strong electrolytes
Nonconductor that doesn’t dissolve
in water
27. How do you determine the oxidation number for elements in a
compound?
Check location on periodic table.
1. Metal groups 1A, 2A, aluminum, zinc, and silver are the same as their
charge.
2. Oxygen is always -2, unless it is with fluorine (+2), or is a peroxide (-1).
3. Hydrogen is always +1 unless it is with a metal (-1).
4. All the rest of the elements are subject to change, so determine these
first, then use these to make the overall charge of the compounds zero.
28. Chromium atoms can take a charge of +2, +3, or +6. Write all of the
possible oxides of chromium.
CrO +2
Cr2O3 +3
CrO3 +6