1. Chemical Bonds and Compounds
CHAPTER
NEW CHAPTER
Chemical Bonds and Compounds
the BIG idea
The properties of compounds depend on their atoms and chemical bonds.
8.1
Elements combine to form compounds.
8.2
Chemical bonds hold compounds together.
8.3
Substances’ properties depend on their bonds.
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2. Elements combine to form compounds.
8.1
Elements combine to form compounds.
CALIFORNIA
Content Standards
8.3.b Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements.
8.5.a Students know reactant atoms and molecules interact to form products with different chemical properties.
chemical formula
subscript
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3. Elements combine to form compounds.
8.1
Elements combine to form compounds.
• Compounds have different properties from the elements that made them.
chemical formula
• Atoms combine in predictable numbers.
subscript + =
calcium (Ca)
chlorine (Cl2)
calcium chloride
(CaCl2)
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4. Compounds have different properties from the elements that make them.
Elements can combine in different combinations, or in different proportions, to make compounds.
Just as the 26 letters of the alphabet can form thousands of words, the 100 or so naturally occurring elements can form millions of compounds.
Compounds have different properties from the elements that make them.
The way the atoms are arranged in a compound also determines some of its properties.

5. 8.1 Atoms combine in predictable numbers. chemical formula
subscript
An expression that shows the number and type of atoms joined in a compound.
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6. 8.1 Atoms combine in predictable numbers. subscript
chemical formula
subscript
subscript
A number written slightly below and to the right of a chemical symbol that shows how many atoms of an element are in a compound.
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7. Chemical bonds hold compounds together.
8.2
Chemical bonds hold compounds together.
CALIFORNIA
Content Standards
8.3.b Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements.
8.3.c Students know atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers.
ionic bond
covalent bond
molecule
polar covalent bond
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8. Chemical bonds hold compounds together.
8.2
Chemical bonds hold compounds together.
• Chemical bonds between atoms involve electrons.
ionic bond
• Atoms can transfer electrons.
• Atoms can share electrons.
covalent bond
• Chemical bonds give all materials their structure.
molecule
polar covalent bond
ionic bond
polar covalent
bond
covalent bond
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9. Chemical bonds hold compounds together.
8.2
Chemical bonds hold compounds together.
• Chemical bonds between atoms involve electrons.
ionic bond
• Atoms can transfer electrons.
• Atoms can share electrons.
covalent bond
• Chemical bonds give all materials their structure.
molecule
polar covalent bond
VISUALIZATON
Examine how electrons move in a polar covalent molecule.
VISUALIZATION
Watch an animation showing ionic and covalent bonding.
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10. 8.2 ionic bond Chemical bonds hold compounds together.
covalent bond
The electrical attraction between a negative ion and a positive ion.
molecule
polar covalent bond
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11. 8.2 covalent bond Chemical bonds hold compounds together.
ionic bond
covalent bond
covalent bond
A pair of electrons shared by two atoms.
molecule
polar covalent bond
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12. 8.2 molecule Chemical bonds hold compounds together.
ionic bond
molecule
covalent bond
A group of atoms that are held together by covalent bonds so that they move as a single unit.
molecule
polar covalent bond
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13. 8.2 polar covalent bond Chemical bonds hold compounds together.
ionic bond
polar covalent bond
covalent bond
The unequal sharing of electrons between two atoms that gives rise to negative and positive regions of electric charge.
molecule
polar covalent bond
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14. Substances’ properties depend on their bonds.
8.3
Substances’ properties depend on their bonds.
CALIFORNIA
Content Standards
8.3.c Students know atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers.
8.7.c Students know substances can be classified by their properties, including their melting temperature, density, hardness, and thermal and electrical conductivity.
metallic bond
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15. Substances’ properties depend on their bonds.
8.3
Substances’ properties depend on their bonds.
• Metals have unique bonds.
• Ionic and covalent bonds give compounds certain properties.
metallic bond
• Bonds can make the same element look different.
copper
graphite fragment
diamond fragment
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16. 8.3 metallic bond Substances’ properties depend on their bonds.
A certain type of bond in which nuclei float in a sea of electrons.
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17. Metallic Bonds Metals have unique bonds.
Metal atoms share electrons equally in all directions.
this allows the electrons to move among the atoms of the metal.

18. Properties of Metals
good conductors of electricity and heat due to the free movement of electrons.
high melting points.
solid at room temperature, except for mercury.
easy to shape by pounding, and easy to draw into a wire.

19. Ionic Bonds Compounds with ionic bonds are hard and brittle.
have very high melting and boiling points.

20. Covalent Bonds
Covalent compounds have much lower boiling and melting points and will not conduct a current when in solution.

21. Bonds can make the same element look different.
Carbon, for example, has three forms: diamond, graphite, and fullerene.
The three forms differ only in the way the carbon atoms are linked together.

22. 8.1 Elements combine to form compounds.
I. Elements combine to form compounds.
chemical formula
A. Compounds have different properties from the elements that make them.
subscript
B. Atoms combine in predictable numbers.
1. Chemical Formulas
2. Same Elements, Different Compounds
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23. Chemical bonds hold compounds together.
8.2
Chemical bonds hold compounds together.
II. Chemical bonds hold compounds together.
ionic bond
A. Chemical bonds between atoms involve electrons.
covalent bond
B. Atoms can transfer electrons.
molecule
1. Ionic Bonds
polar covalent bond
2. Names of Ionic Compounds
C. Atoms can share electrons.
1. Covalent Bonds
2. Polar Covalent Bonds
D. Chemical bonds give all materials their structures.
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1. Ionic Compounds
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2. Covalent Compounds

24. Substances’ properties depend on their bonds.
8.3
Substances’ properties depend on their bonds.
III. Substances’ properties depend on their bonds.
metallic bond
A. Metals have unique bonds.
B. Ionic and covalent bonds give compounds certain properties.
C. Bonds can make the same element look different.
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