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Chapter Menu

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Chapter Introduction Lesson 1 Electrons and Energy Levels Lesson 2 Compounds, Chemical Formulas, and Covalent Bonds Lesson 3 Ionic and Metallic Bonds – PowerPoint PPT presentation

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Title: Chapter Menu


1
Chapter Menu
Chapter Introduction Lesson 1 Electrons and
Energy Levels Lesson 2 Compounds, Chemical
Formulas, and Covalent Bonds Lesson 3 Ionic
and Metallic Bonds Chapter Wrap-Up
2
Chapter Introduction
  • How do elements join together to form chemical
    bonds?

3
Chapter Introduction
  • What do you think?

Before you begin, decide if you agree or disagree
with each of these statements. As you view this
presentation, see if you change your mind about
any of the statements.
4
Chapter Introduction
Do you agree or disagree?
  • 1. Elements rarely exist in pure form. Instead,
    combinations of elements make up most of the
    matter around you.
  • 2. Chemical bonds that form between atoms involve
    electrons.

5
Chapter Introduction
Do you agree or disagree?
  • 3. The atoms in a water molecule are more
    chemically stable than they would be as
    individual atoms.
  • 4. Many substances dissolve easily in water
    because opposite ends of a water molecule have
    opposite charges.

6
Chapter Introduction
Do you agree or disagree?
  • 5. Losing valence electrons can make some atoms
    more chemically stable.
  • 6. Metals are good electrical conductors because
    they tend to hold onto their valence electrons
    very tightly.

7
Lesson 1 Reading Guide - KC
Electrons and Energy Levels
  • How is an electrons energy related to its
    distance from the nucleus?
  • Why do atoms gain, lose, or share electrons?

8
Lesson 1 Reading Guide - Vocab
Electrons and Energy Levels
  • chemical bond
  • valence electron
  • electron dot diagram

9
Lesson 1-1
The Periodic Table
  • Elements on the periodic table are organized in
    periods (rows) and groups (columns).
  • The periodic table lists elements in order of
    atomic number, which increases from left to right
    as you move across a period.

10
Lesson 1-1
  • The three main regions of elements on the
    periodic table classify elements as metals,
    nonmetals, or metalloids.

11
Lesson 1-1
The Periodic Table (cont.)
  • Except for hydrogen, elements on the left side of
    the table are metals.
  • Nonmetals are on the right side of the table.
  • Metalloids form the narrow stair-step region
    between metals and nonmetals.

12
Lesson 1-2
Atoms Bond
  • A chemical bond is a force that holds two or more
    atoms together in a compound.
  • Atoms contain protons, neutrons, and electrons.
  • Each proton has a positive charge each neutron
    has no charge and each electron has a negative
    charge.

13
Lesson 1-2
  • Protons and neutrons are in an atoms nucleus.
    Electrons move around the nucleus.

14
Lesson 1-2
Atoms Bond (cont.)
  • The atomic number of an element is the number of
    protons in each atom of that element.
  • An electron moves around the nucleus at a
    distance that corresponds to its amount of energy.

15
Lesson 1-2
Atoms Bond (cont.)
  • Areas of space in which electrons move around the
    nucleus are called energy levels.
  • Electrons closest to the nucleus have the least
    amount of energy. Electrons farthest from the
    nucleus have the greatest amount of energy.

16
Lesson 1-2
Electron Energy Levels
17
Lesson 1-2
Atoms Bond (cont.)
How is an electrons energy related to its
position in an atom?
18
Lesson 1-2
Atoms Bond (cont.)
  • The attraction between the positive nucleus of
    one atom and the negative electrons of another
    atom is what creates a chemical bond.
  • A valence electron is an outermost electron of an
    atom that participates in chemical bonding.

19
Lesson 1-2
Atoms Bond (cont.)
valence from Latin valentia, means strength,
capacity
  • The number of valence electrons in each atom of
    an element can help determine the type and number
    of bonds that an atom can form.

20
Lesson 1-2
  • The periodic table can tell you how many valence
    electrons an atom has.

21
Lesson 1-2
Atoms Bond (cont.)
  • In 1916 an American chemist named Gilbert Lewis
    developed the electron dot diagram, a model that
    represents valence electrons in an atom as dots
    around the elements chemical symbol.

22
Lesson 1-3
23
Lesson 1-2
Atoms Bond (cont.)
  • Atoms with eight valence electrons are chemically
    stable and do not easily react with other atoms.
  • Atoms that have between one and seven valence
    electrons are reactive or chemically unstable and
    easily bond with other atoms to form chemically
    stable compounds.

24
Lesson 1-2
Atoms Bond (cont.)
  • The elements in group 18 are called noble gases.
  • With the exception of helium, noble gases have
    eight valence electrons and are chemically stable.

25
Lesson 1-2
  • Atoms gain, lose, or share valence electrons and
    become chemically stable.

26
Lesson 1-2
Atoms Bond (cont.)
Why do atoms gain, lose, or share electrons?
27
Lesson 1 - VS
  • Electrons are less strongly attracted to a
    nucleus the farther they are from it, similar to
    the way a magnet attracts a paper clip.

28
Lesson 1 - VS
  • Electrons in atoms are in energy levels around
    the nucleus. Valence electrons are involved in
    chemical bonding.

29
Lesson 1 - VS
  • All noble gases, except He, have four pairs of
    dots in their electron dot diagrams. Noble gases
    are chemically stable.

30
Lesson 1 LR1
Where on the periodic table are nonmetals located?
A. the left side B. the right side C. the
middle D. all of the above
31
Lesson 1 LR2
Which term refers to areas of space in which
electrons move around the nucleus?
A. electron dot diagram B. periodic
table C. neutron D. energy levels
32
Lesson 1 LR3
All of the elements in group 18 are called what?
A. metalloids B. valence electrons C. noble
gases D. metals
33
Lesson 1 - Now
Do you agree or disagree?
  • 1. Elements rarely exist in pure form. Instead,
    combinations of elements make up most of the
    matter around you.
  • 2. Chemical bonds that form between atoms involve
    electrons.

34
Lesson 2 Reading Guide - KC
Compounds, Chemical Formulas, and Covalent Bonds
  • How do elements differ from the compounds they
    form?
  • What are some common properties of a covalent
    compound?
  • Why is water a polar compound?

35
Lesson 2 Reading Guide - Vocab
Compounds, Chemical Formulas, and Covalent Bonds
  • covalent bond
  • molecule
  • polar molecule
  • chemical formula

36
Lesson 2-1
From Elements to Compounds
  • Compounds are chemical combinations of different
    types of atoms.
  • Chemical bonds join atoms together.

37
Lesson 2-1
From Elements to Compounds (cont.)
bond Science Use a force that holds atoms
together in a compound Common Use a close
personal relationship between two people
38
Lesson 2-1
From Elements to Compounds (cont.)
How is a compound different from the elements
that make it up?
39
Lesson 2-2
Covalent BondsElectron Sharing
  • A covalent bond is a chemical bond formed when
    two atoms share one or more pairs of valence
    electrons.
  • A compound formed from many covalent bonds is
    called a covalent compound.

40
Lesson 2-2
  • Atoms with less than eight valence electrons
    become chemically stable by forming a chemical
    bond.

41
Lesson 2-2
Covalent BondsElectron Sharing (cont.)
  • A single covalent bond exists when two atoms
    share one pair of valence electrons.
  • A double covalent bond exists when two atoms
    share two pairs of valence electrons
  • A triple covalent bond exists when two atoms
    share three pairs of valence electrons.

42
Lesson 2-2
  • The more valence electrons that two atoms share,
    the stronger the covalent bond is between the
    atoms.

43
Lesson 2-3
Covalent Compounds
  • When two or more atoms share valence electrons,
    they form a stable covalent compound.
  • Covalent compounds usually have low melting
    points and low boiling points.
  • They are usually gases or liquids at room
    temperature, but they can also be solids.
  • Covalent compounds are poor conductors of thermal
    energy and electricity.

44
Lesson 2-3
Covalent Compounds (cont.)
What are some common properties of covalent
compounds?
45
Lesson 2-3
Covalent Compounds (cont.)
  • A molecule is a group of atoms held together by
    covalent bonding that acts as an independent
    unit.
  • A molecule that has a partial positive end and a
    partial negative end because of unequal sharing
    of electrons is a polar molecule.

46
Lesson 2-3
Covalent Compounds (cont.)
polar from Latin polus, means pole
47
Lesson 2-4
  • Atoms of a polar molecule share their valence
    electrons unequally.

48
Lesson 2-4
  • Atoms of a nonpolar molecule share their valence
    electrons equally.

49
Lesson 2-4
Covalent Compounds (cont.)
Why is water a polar compound?
50
Lesson 2-3
Covalent Compounds (cont.)
  • A chemical formula is a group of chemical symbols
    and numbers that represent the elements and the
    number of atoms of each element that make up a
    compound.
  • A chemical formula describes the types of atoms
    in a compound or a molecule, but it does not
    explain the shape or appearance of the molecule.

51
Lesson 2-4
  • Chemical formulas and molecular models provide
    information about molecules.

52
Lesson 2 - VS
  • A chemical formula is one way to show the
    elements that make up a compound.

53
Lesson 2 - VS
  • A covalent bond forms when atoms share valence
    electrons. The smallest particle of a covalent
    compound is a molecule.

54
Lesson 2 - VS
  • Water is a polar molecule because the oxygen and
    hydrogen atoms unequally share electrons.

55
Lesson 2 LR1
Which term refers to chemical combinations of
different types of atoms?
A. covalent bond B. chemical formula C. compound D
. polar molecule
56
Lesson 2 LR2
When two atoms share one pair of valence
electrons, which of the following exists?
A. single covalent bond B. double covalent
bond C. triple covalent bond D. none of these
57
Lesson 2 LR3
Which term refers to a molecule that has a
partial positive end and a partial negative end
because of unequal sharing of electrons?
A. covalent bond B. polar molecule C. nonpolar
molecule D. covalent compound
58
Lesson 2 - Now
Do you agree or disagree?
3. The atoms in a water molecule are more
chemically stable than they would be as
individual atoms. 4. Many substances dissolve
easily in water because opposite ends of a water
molecule have opposite charges.
59
Lesson 3 Reading Guide - KC
Ionic and Metallic Bonds
  • What is an ionic compound?
  • How do metallic bonds differ from covalent and
    ionic bonds?

60
Lesson 3 Reading Guide - Vocab
Ionic and Metallic Bonds
  • ion
  • ionic bond
  • metallic bond

61
Lesson 3-1
Understanding Ions
  • An ion is an atom that is no longer electrically
    neutral because it has lost or gained valence
    electrons.

ion from Greek ienai, means to go
62
Lesson 3-1
Understanding Ions (cont.)
  • Because electrons have a negative charge, losing
    or gaining an electron changes the overall charge
    of an atom.
  • Atoms that lose valence electrons become ions
    with a positive charge.
  • Metal atoms, such as sodium, become more stable
    when they lose valence electrons and form a
    chemical bond with a nonmetal.

63
Lesson 3-1
  • Sodium atoms have a tendency to lose a valence
    electron. Chlorine atoms have a tendency to gain
    a valence electron.

64
Lesson 3-1
Understanding Ions (cont.)
  • Atoms are electrically neutral because they have
    the same number of protons and electrons.
  • Once an atom gains or loses electrons, it becomes
    a charged ion.

65
Lesson 3-2
Ionic BondsElectron Transferring
  • When forming a compound, the nonmetal atoms gain
    the electrons lost by the metal atoms.
  • The attraction between positively and negatively
    charged ions in an ionic compound is an ionic
    bond.

66
Lesson 3-2
  • An ionic bond forms between Na and Cl when an Na
    atom transfers an electron to a Cl atom.

67
Lesson 3-2
Ionic BondsElectron Transferring (cont.)
What holds ionic compounds together?
68
Lesson 3-3
Ionic Compounds
  • Individual ions in an ionic compound are strongly
    attracted to each other.
  • Covalent compounds are made up of many molecules.
  • When nonmetal ions bond to metal ions in an ionic
    compound there is a large collection of
    oppositely charged ions and no molecules.

69
Lesson 3-4
Metallic BondsElectron Pooling
  • A metallic bond is a bond formed when many metal
    atoms share their pooled valence electrons.
  • Valence electrons in metals are not bonded to one
    atom.
  • Instead, a sea of electrons surrounds the
    positive ions.

70
Lesson 3-4
  • Valence electrons are free to move among all the
    aluminum (Al) ions.

71
Lesson 3-4
Metallic BondsElectron Pooling (cont.)
How do metal atoms bond with one another?
72
Lesson 3-4
Metallic BondsElectron Pooling (cont.)
  • Metals are good conductors of thermal energy and
    electricity.
  • Metals are shiny because the valence electrons at
    the surface of a metal interact with light.

73
Lesson 3-4
74
Lesson 3-4
75
Lesson 3 - VS
  • Metal atoms lose electrons and nonmetal atoms
    gain electrons and form stable compounds. An atom
    that has gained or lost an electron is an ion.

76
Lesson 3 - VS
  • An ionic bond forms between positively and
    negatively charged ions.

77
Lesson 3 - VS
  • A metallic bond forms when many metal atoms share
    their pooled valence electrons.

78
Lesson 3 LR1
Which of these describes an atom that is no
longer electrically neutral because it has lost
or gained valence electrons ?
A. covalent compound B. proton C. ion D. molecule
79
Lesson 3 LR2
What is a bond formed when many metal atoms share
their pooled valence electrons?
A. ionic bond B. metallic bond C. covalent
compound D. ionic compound
80
Lesson 3 LR3
An ionic bond is the attraction between
positively and negatively charged ions in which
of these?
A. valence electrons B. covalent
compound C. ionic compound D. none of these
81
Lesson 3 - Now
Do you agree or disagree?
5. Losing valence electrons can make some atoms
more chemically stable. 6. Metals are good
electrical conductors because they tend to hold
onto their valence electrons very tightly.
82
Chapter Review Menu
Key Concept Summary Interactive Concept
Map Chapter Review Standardized Test Practice
83
The BIG Idea
  • Elements can join together by sharing,
    transferring, or pooling electrons to make
    chemical compounds.

84
Key Concepts 1
Lesson 1 Electrons and Energy Levels
  • Electrons with more energy are farther from the
    atoms nucleus and are in a higher energy level.
  • Atoms with fewer than eight valence electrons
    gain, lose, or share valence electrons and
    form stable compounds. Atoms in stable
    compounds have the same electron arrangement as
    a noble gas.

85
Key Concepts 2
Lesson 2 Compounds, Chemical Formulas, and
Covalent Bonds
  • A compound and the elements it is made from have
    different chemical and physical properties.
  • A covalent bond forms when two nonmetal atoms
    share valence electrons. Common properties of
    covalent compounds include low melting points and
    low boiling points. They are usually gas or
    liquid at room temperature and poor conductors of
    electricity.
  • Water is a polar compound because the oxygen atom
    pulls more strongly on the shared valence
    electrons than the hydrogen atoms do.

86
Key Concepts 3
Lesson 3 Ionic and Metallic Bonds
  • Ionic bonds form when valence electrons from a
    metal atom transfers to a nonmetal atom.
  • An ionic compound is held together by ionic
    bonds, which are attractions between positively
    and negatively charged ions.
  • A metallic bond forms when valence electrons are
    pooled among many metal atoms.

87
Chapter Review MC1
Which term refers to a force that holds two or
more atoms together in a compound?
A. valence electron B. positive
charge C. chemical bond D. negative charge
88
Chapter Review MC2
Which of these is the outermost electron of an
atom that participates in chemical bonding?
A. valence electron B. nucleus C. negative
electrons D. proton
89
Chapter Review MC3
Which of these is a group of atoms held together
by covalent bonding that acts as an independent
unit?
A. electron B. proton C. molecule D. valence
electrons
90
Chapter Review MC4
Which of these describes a chemical bond formed
when two atoms share one or more pairs of valence
electrons?
A. polar molecule B. covalent bond C. chemical
compound D. none of these
91
Chapter Review MC5
A metallic bond is a bond formed when many metal
atoms share what?
A. their pooled valence electrons B. ions C. charg
ed ions D. molecules
92
Chapter Review STP1
Which of these is a model that represents valence
electrons in an atom as dots around the elements
chemical symbol?
A. periodic table B. energy level C. atomic
number D. electron dot diagram
93
Chapter Review STP2
Which term describes atoms with unpaired dots in
their electron dot diagrams?
A. reactive B. chemically unstable C. chemically
stable D. A and B
94
Chapter Review STP3
Which of these describes a group of chemical
symbols and numbers that represent the elements
and the number of atoms of each element that make
up a compound?
A. chemical bond B. chemical formula C. covalent
bond D. molecule
95
Chapter Review STP4
Once an atom gains or loses electrons, it becomes
which of these?
A. charged ion B. covalent compound C. molecule D.
proton
96
Chapter Review STP5
Which of these refers to the attraction between
positively and negatively charged ions in an
ionic compound?
A. metallic bond B. ionic bond C. covalent
compound D. none of these
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