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Elements and Chemical Bonds 49
Lesson 2
Predict three facts that will be discussed in Lesson 2 after reading the headings. Record your
predictions in your Science Journal.
Copyright © McGraw-Hill Education.
Compounds, Chemical Formulas, and Covalent Bonds
From Elements
to Compounds
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Recall information about elements and compounds. Read each
statement. If it is true, write T in the center column. If it is false, write
F in the center column and rewrite the underlined words to make the
statement true.
Statement T or F Correction
Compounds are chemical
combinations of elements.
Compounds usually have the
same properties as the bonds
they are made from.
Atoms form bonds by sharing
physical properties.
Define covalent bond.
Describe types of covalent bonds.
Covalent
Bond
Description of
Valence Electron
Sharing
Comment on the
Strength of the
Bond
Single
Double
Triple
Covalent Bonds—
Electron Sharing
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T
F
Is a chemical bond formed when two atoms share one
or more electrons.
When two hydrogen
atoms bond, they form a
single covalent bond
In a single covalent bond, 1p
Covalent Bond
electrons is shared between)
H:H
atoms. Each H atom shares 1,
electron with the other.
When one carbon atom bonds with
two oxygen atoms, two double In a double covalent bond, 2 pairs
of electrons are shared between two
atoms. One O atom and the C atom
each share 2 valence electrons with
the other.
F The sharing of
electrons causes
bonds
The book says the
don’t have the
same property’s
When two nitrogen
atoms bond they form
a triple covalent bond
In a triple covalent bond, 3 pairs of
electrons are shared between two
atoms. Each N atom shares 3 valene
electrons with the other.
50 Elements and Chemical Bonds
Lesson 2 | Compounds, Chemical Formulas, and Covalent Bonds (continued)
Copyright © McGraw-Hill Education.
Identify 4 common properties of covalent compounds.
1.
2.
3.
4.
Covalent Compounds
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Complete the analogy.
Atom is to element as is to
compound.
Summarize the structure of polar molecules.
sharing of
results in
polar
molecule
a partial
and a partial
Explain why water is a polar molecule.
Differentiate polar and nonpolar molecules with regard to shared
electrons.
Polar Molecules Nonpolar Molecules
Relate the saying “like dissolves like” to the ability of compounds to
dissolve one another.
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The boiling/melting points of covalent compounds are low.
They are soft in nature and relatively flexible.
These compounds do not possess electrical conductivity.
They have lower values of enthalpy of fusion/vaporization.
Share
Molecules
Bonding
Adds
Be removed
A molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons
A water molecule is polar because the shared
electrons are pulled closer to the oxygen atom
than the hydrogen atoms.
A carbon dioxide molecule is non-
polar because the shared electrons
are pulled equally by the carbon
atom and the oxygen atoms
Suger dissolves in water l
Elements and Chemical Bonds 51
Lesson 2 | Compounds, Chemical Formulas, and Covalent Bonds (continued)
Copyright © McGraw-Hill Education.
Explain why there are many more covalent compounds than there are pure
elements.
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Define chemical formula.
Explain the chemical formula for a molecule of water. Describe
what each symbol represents.
H2O
Identify four types of molecular models.
Molecular
Models
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t
Is a group of chemical symbols and number of atoms of each element that makes up a compound.
Hydrogen Hydrogen Oxygen
Dot Diagram Structural Formula
Ball-and-Stick Model Space-Filling Model
Because you have to mix chemicals to form a compound