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Unit I – The Nature of Matter
Chapter 4 – The Structure of Matter
Objectives:
Students will be able to:
1. Relate the chemical formula of a compound to
the relative numbers of atoms or ions present in
the compound.
2. Use models to visualize a compound’s chemical
structure.
3. Describe how the chemical structure of a
compound affects its properties.
4. Explain why atoms sometimes join to form
bonds.
5. Explain why some atoms transfer their valence
electrons to form ionic bonds, while other atoms
share valence electrons to form covalent bonds.
6. Name simple ionic and covalent compounds.
7. Identify the names and structures of groups of
simple organic compounds.
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I. Compounds
A. Compounds
1. chemical bonds
a. the attractive force that holds
atoms or ions together
2. a compound always has the same
chemical formula
a. water – H2O
b. salt – NaCl
c. table sugar – C12H22O11
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3. Molecular formula
a. a chemical formula that shows
the number and kinds of atoms
in a molecule, but not the
arrangement of atoms
1) H2O
2) NaCl
3) C12H22O11
4. Chemical structure/Structural
formula
a. a formula that indicates the
location of the atoms, groups,
or ions relative to one another
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in a molecule and that indicates
the number and location of
chemical bonds
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B. How does structure affect properties?
1. compounds with network
structures are strong solids
a. quartz and sand – SiO2
b. high melting and boiling points
c. requires a lot of energy to break
the bonds
2. some networks are made of
bonded positive and negative ions
a. salt – NaCl
b. Na+ and Cl- ions are bonded
together forming large
networks
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c. increases strength, high melting
and boiling points
3. some compounds are made of
molecules
a. table sugar – C12H22O11
b. strong attraction between the
atoms, but weak attraction
between the molecules
II. Ionic and Covalent Bonding
A. What holds bonded atoms together?
1. the outermost energy level of a
bonded atom is full of electrons
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2. bonds can bend and stretch without
breaking
B. Ionic Bonds
1. a bond formed by the attraction
between oppositely charged ions
a. ion – an atom or group of atoms
that has lost or gained one or
more electrons and has a
negative (anion) or a positive
(cation) charge
b. Lithium – 3 e-
if it loses its one valence e-,
then it has a positive charge
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3 p+, 4 n0, 2 e- = 1+ charge
c. Fluorine – 9 e-
if it gains one valence e-, then it
has a negative charge
9 p+, 10 n0, 10 e- = 1- charge
2. formed by the transfer of e-
3. ie – NaCl
4. ionic compounds are in the form of
networks, not molecules
5. when melted or dissolved in water,
ionic compounds conduct
electricity
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C. Metallic Bonds
1. a bond formed by the attraction
between positively charged metal
ions and the electrons around them
D. Covalent Bonds
1. a bond formed when atoms share
one or more pairs of electrons
2. often formed between non-metals
3. water (H2O) and sugar (C12H22O11)
4. usually have a low melting point
5. do not conduct electricity because
they are not charged
6. bonding
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7. atoms are not always shared
equally
E. Polyatomic Ions
1. an ion made of two or more atoms
a. OH- hydroxide ion
b. CO32- carbonate ion
c. NH4+ ammonium ion
2. some compounds have both ionic
and covalent bonds – made of
polyatomic ions
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III. Compound Names and Formulas
A. Naming Ionic Compounds
1. Names of cations (+) include the
elements of which they are
composed
2. Names of anions are altered names
of elements
3. Some cations must show their
charge
4. Determining the charge of a
transition metal cation
a. the total charge of an ionic
compound must be zero
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b. for example
Iron (III) ion and Oxide ion
Fe charge of 3+
oxide ion 2-
total charge of iron 6+
need two iron ions
total charge of oxide ions 6-
need three oxide ions
Fe2O3
5. Writing Ionic Formulas
* What is the chemical formula
for aluminum floride?
a. list the symbols for each ion
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aluminum Al3+
fluoride F-
b. write the symbols for the ions
with the cation first
Al3+ F-
c. find the least common multiple
of the ions’ charges
least common multiple of 3 and
1 is 3
to get three positive charges,
need only one Al3+
to get three negative charges,
need three F-
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d. write the chemical formula,
indicating with subscripts how
many of each ion are needed to
make a neutral compound
AlF3
6. Problems
1. lithium oxide Li2O
2. beryllium chloride BeCl2
3. titanium (III) nitride TiN
4. cobalt (III) hydroxide Co(OH)3
5. magnesium bromide MgBr2
6. rubidium oxide Rb2O
7. lithium nitride Li3N
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8. potassium sulfate K2SO4
B. Naming Covalent Compounds
1. Numerical prefixes are used to
name covalent compounds of two
elements
2. mono is not used on the first
element in the formula
3. Examples
1. N2O4 Dinitrogen tetroxide
2. BF3 boron trifluoride
3.
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IV. Organic and Biochemical
Compounds
A. Organic compound
1. a covalently bonded compound
that contains carbon
2. organism – a living thing
3. living things are made of organic
compounds
B. Carbohydrates
C. Proteins
1. amino acids
2. DNA – deoxyribonucleic acid
3. RNA – ribonucleic acid
D. Lipids
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