Name
Date
Class
Lesson Outline
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
A. From Elements to Compounds
1. Compounds are chemical combinations of two or
more
.
2. Compounds and the elements that form them often have very different chemical
and physical
.
3. Atoms can bond to form compounds by
valence
electrons.
4. A(n)
is a group of chemical symbols and numbers that
represent the elements and the numbers of atoms of each element in a compound.
5. The letters in a chemical formula represent
6.
.
show the shape and appearance of the arrangement of
atoms in a compound.
B. Covalent Bonds—Electron Sharing
1. A(n)
is a chemical bond formed when two or more
atoms share one or more pairs of valence electrons.
2. When forming water, valence electrons are
between
oxygen and hydrogen atoms, thereby forming covalent bonds to make three stable
atoms.
C. Covalent Compounds
1. A(n)
is a group of atoms held together by covalent
bonding that acts as an independent unit.
2.
generally have low melting points and low boiling
points. They are
conductors of electricity.
a. In a hydrogen molecule, a(n)
covalent bond forms
when each atom shares its valence electrons with the other.
b. In a carbon dioxide molecule, a double covalent bond forms when the carbon
atom shares
pairs of valence electrons with each
oxygen atom.
Elements and Chemical Bonds
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Name
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Lesson Outline continued
c. In a(n)
covalent bond, three pairs of valence
electrons are shared between two atoms.
d.
covalent bonds are stronger than
covalent bonds, which are stronger than single
covalent bonds.
3. In a covalent bond, one atom can attract the shared electrons more
than the other atom can.
a. In a molecule of water, the
atom attracts the
electrons more strongly than each hydrogen atom does.
b. Because the electrons have a slight negative charge, there is a slight negative
charge near the
atom; there is a slight
charge near the hydrogen atoms.
c. A molecule that has a slight positive end and a slight negative end because of
unequal sharing of electrons is a(n)
d. Polar molecules, such as sugar and water,
.
easily in
one another because of the attraction of opposite charges.
4. Molecules made up of atoms of the same element are
because the atoms are identical. So, they share electrons equally.
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Elements and Chemical Bonds
Name
Date
Class
Content Practice A
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Directions: On the line before each statement, write T if the statement is true or F if the statement is false.
1. A compound is a substance that is composed of two or more different kinds
of molecules.
2. Compounds are held together by chemical bonds.
3. CO2 is the structural formula of carbon dioxide.
4. When nonmetals combine with other nonmetals, they usually form covalent
bonds.
5. A covalent bond is a chemical bond formed when two or more atoms share
one or more pairs of valence electrons.
6. A molecule is a group of atoms held together by covalent bonding that acts as
an independent unit.
7. Compounds formed with covalent bonds usually have high melting and
boiling points.
8. Compounds formed with covalent bonds are good conductors of electricity.
9. A polar molecule has a slight positive end and a slight negative end because of
the unequal sharing of electrons.
10. Water is an example of a polar molecule.
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Elements and Chemical Bonds
Name
Date
Class
Content Practice B
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Directions: On each line, write the term that correctly completes each sentence.
1.
is the chemical formula of carbon dioxide.
2. One carbon dioxide molecule consists of
and
carbon atom(s)
oxygen atom(s).
3. When nonmetals form compounds by joining with other nonmetals, they tend to
establish
bonds.
4. A(n)
is a group of atoms held together by covalent bonding
that acts as an independent unit.
5. These compounds are usually
or
at room temperature.
6. These compounds usually have low
and
points.
7. In addition, they are poor conductors of
.
8. A molecule that has a slight positive end and a slight negative end is called a(n)
molecule.
Elements and Chemical Bonds
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Name
Date
Class
School to Home
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Directions: Use your textbook to answer each question.
1. A chemical formula represents a substance called a compound. For
example, the chemical formula for table salt is NaCl. The chemical
compound for water is H2O.
What does a chemical formula tell you? What information about the compound is not
part of a chemical formula?
2. When nonmetal atoms join with other nonmetal atoms, they tend to form
covalent bonds.
What makes nonmetals more likely to form covalent bonds?
3. A molecule is a group of atoms held together by covalent bonding that acts
as an independent unit.
Which properties do molecules usually share?
4. Charges on polar molecules affect the properties of the molecule.
What is a polar molecule?
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Elements and Chemical Bonds
Name
Date
Class
Key Concept Builder
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Key Concept How do elements differ from the compounds they form?
Directions: Complete this spider map by choosing terms and phrases from the word bank and writing them in
the correct spaces. On each top line, give the name of the model. On each bottom line, give its main function. The
map has been started for you.
ball-and-stick model
shows elements and shared pairs of electrons
shows number of atoms in elements
electron dot diagram
shows elements and valence electrons
structural formula
chemical formula
2.
1.
3.
Describing
Chemical
Compounds
4.
5.
6.
shows bond angles
Directions: Answer the question on the lines provided.
7. In a chemical formula, such as H2O (water), what does a small number next to an
element’s symbol tell you?
Elements and Chemical Bonds
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Name
Date
Class
Key Concept Builder
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Key Concept What are some common properties of a covalent compound?
Directions: This diagram is a schematic drawing of the top six rows of the periodic table. Use the diagram to
answer each question on the lines provided.
1. Which elements are in the shaded area?
2. What kind of bonds do these elements tend to make when they combine with one
another?
3. What is the definition of this kind of bond?
4. Which element located outside the shaded area forms many of this same kind of bond?
5. Where is that element in the diagram?
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Elements and Chemical Bonds
Name
Date
Class
Key Concept Builder
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Key Concept What are some common properties of a covalent compound?
Directions: Put a check mark on the line before each property that is typical of a covalent compound.
1. liquid or gas at room temperature
2. metallic luster
3. low melting point
4. always solid at room temperature
5. poor conductor of electricity
6. very high boiling point
7. chemically unstable
8. made up of molecules
Directions: On the line before each description, write S if it is held together by a single bond, D if it is held
together by a double bond, and T if it is held together by a triple covalent bond.
9. molecular nitrogen (N2)
10. molecular hydrogen (H2)
11. carbon dioxide (CO2)
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Name
Date
Class
Lesson Quiz A
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
True or False
Directions: On the line before each statement, write T if the statement is true or F if the statement is false.
1. A compound can have different chemical and physical properties than those
of the elements it is made from.
2. A chemical formula shows the total number of atoms in a sample of a
compound.
3. A molecule is a group of atoms held together by covalent bonding that acts as
an independent unit.
4. A polar molecule is one that has equal electron attraction between atoms.
Multiple Choice
Directions: On the line before each question or statement, write the letter of the correct answer.
5. In the chemical formula H2O, how many atoms of oxygen are represented?
A. one
B. two
C. three
6. Which compound is a polar molecule?
A. H2
B. H2O
C. CO2
7. A double covalent bond is created when
A. two atoms share one pair of valence electrons.
B. two atoms share bonds with four other atoms.
C. two atoms share two pairs of valence electrons.
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Elements and Chemical Bonds
Name
Date
Class
Lesson Quiz B
LESSON 2
Compounds, Chemical Formulas, and Covalent Bonds
Completion
Directions: On each line, write the term that correctly completes each sentence.
1. A(n)
can have different chemical and physical properties
than those of the elements it is made from.
2. A(n)
is a group of chemical symbols and numbers that
represent the elements and the numbers of atoms of each element that make up a
compound.
3. A(n)
is a group of atoms held together by covalent bonding
that acts as an independent unit.
4. A polar molecule has a slight
charge near the atom that
attracts the shared electron more strongly.
Short Answer
Directions: Respond to each statement on the lines provided.
5. List the types and numbers of atoms represented in the chemical formula for
methane, CH4.
6. Describe how polar and nonpolar liquids can be used to dissolve different substances.
7. Explain how double and triple covalent bonds occur.
Elements and Chemical Bonds
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