4. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
5. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
6. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
1.by losing electrons
7. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
1.by losing electrons
2.by gaining electrons
8. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
1.by losing electrons
2.by gaining electrons
3.by pooling electrons
9. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
1.by losing electrons
2.by gaining electrons
3.by pooling electrons
4.by sharing electrons with another element
10. Bonding
Atoms form bonds with other atoms using the
electrons in their outer energy levels.
Atoms have four ways to do form bonds.
1.by losing electrons
2.by gaining electrons
3.by pooling electrons
4.by sharing electrons with another element
We will be studying each of these in Section 2.
14. Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to
chlorine.What makes sodium so reactive?
15. Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to
chlorine.What makes sodium so reactive?
Sodium has only one electron in its outer level.
Removing this electron empties this level and leaves the
completed level below. Sodium is then stable.
16. Sodium and Chlorine
Sodium is a soft, silvery metal.
It can react violently when added to water or to
chlorine.What makes sodium so reactive?
Sodium has only one electron in its outer level.
Removing this electron empties this level and leaves the
completed level below. Sodium is then stable.
Chlorine forms bonds in a way that is the opposite
of sodium—it gains one electron. When chlorine
accepts an electron, its electron configuration becomes
stable.
19. Forming Ions
As sodium atoms lose an electron they become
more stable.
20. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
21. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
22. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
=
23. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
= 11 protons
11 electrons
(neutral)
24. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
= 11 protons
11 electrons
(neutral)
but
25. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
= 11 protons
11 electrons
(neutral)
but
after losing
one electron
26. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
= 11 protons
11 electrons
(neutral)
but
after losing 11 protons
one electron 10 electrons
(positively charged)
27. Forming Ions
As sodium atoms lose an electron they become
more stable.
But by losing an electron, the balance of electric
charges changes.
= 11 protons
11 electrons
(neutral)
but
after losing 11 protons
one electron 10 electrons
(positively charged)
Sodium becomes a positively charged ion because
there is now one fewer electron than there are
protons in the nucleus.
30. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
31. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
32. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
=
33. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
= 17 protons
17 electrons
(neutral)
34. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
= 17 protons
17 electrons
(neutral)
but
35. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
= 17 protons
17 electrons
(neutral)
after gaining
but one electron
36. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
= 17 protons
17 electrons
(neutral)
after gaining 17 protons
but one electron 18 electrons
(negatively charged)
37. Forming Ions
In contrast, chlorine becomes an ion by gaining an
electron.
= 17 protons
17 electrons
(neutral)
after gaining 17 protons
but one electron 18 electrons
(negatively charged)
It becomes negatively charged because there is one
more electron than there are protons in the nucleus.
40. Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
41. Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
Sodium ion is represented by the symbol Na+
42. Forming Ions
An atom that is no longer neutral because it has
lost or gained an electron is called an ion.
Sodium ion is represented by the symbol Na+
A chloride ion is represented by the symbol Cl-
44. Bond Formation
The positive sodium ion and the negative chloride
ion are strongly attracted to each other.
45. Bond Formation
The positive sodium ion and the negative chloride
ion are strongly attracted to each other.
This attraction, which holds the ions close
together, is a type of chemical bond called an
ionic bond.
46. Bond Formation
The positive sodium ion and the negative chloride
ion are strongly attracted to each other.
This attraction, which holds the ions close
together, is a type of chemical bond called an
ionic bond.
49. Bond Formation
Sodium and chloride ions form an ionic bond.
The compound sodium chloride, or table salt, is
formed. A compound is a pure substance
containing two or more elements that are
chemically bonded.
50. Bond Formation
Sodium and chloride ions form an ionic bond.
The compound sodium chloride, or table salt, is
formed. A compound is a pure substance
containing two or more elements that are
chemically bonded.
54. More Gains and Loses
Can elements lose or gain more than one electron?
55. More Gains and Loses
Can elements lose or gain more than one electron?
Yes!!
56. More Gains and Loses
Can elements lose or gain more than one electron?
Yes!!
Magnesium, Mg, in Group 2 has two electrons in its
outer energy level.
Magnesium can lose these two electrons and
achieve a completed energy level.
57. More Gains and Loses
Can elements lose or gain more than one electron?
Yes!!
Magnesium, Mg, in Group 2 has two electrons in its
outer energy level.
Magnesium can lose these two electrons and
achieve a completed energy level.
Oxygen, O, in Group 16 has six electrons in its outer
energy level.
Oxygen can gain two electrons and achieve a
completed energy level.
58.
59.
60. The two electrons, in magnesiums outer energy level, can be
gained by two chlorine atoms.
61. The two electrons, in magnesiums outer energy level, can be
gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to
the positively charged magnesium ion forming ionic bonds.
62. The two electrons, in magnesiums outer energy level, can be
gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to
the positively charged magnesium ion forming ionic bonds.
The compound magnesium chloride (MgCl2) is produced.
63. The two electrons, in magnesiums outer energy level, can be
gained by two chlorine atoms.
The two negatively charged chloride ions are attracted to
the positively charged magnesium ion forming ionic bonds.
The compound magnesium chloride (MgCl2) is produced.
67. Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic
bonds with atoms of nonmetals.
68. Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic
bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in
a different way.
69. Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic
bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in
a different way.
In a metal, the electrons in the outer energy levels of
the atoms are not held tightly to individual atoms.
Instead, they move freely among all the ions in the
metal, forming a shared pool of electrons.
70. Metallic Bonding - Pooling
We have just looked at how metal atoms form ionic
bonds with atoms of nonmetals.
Metals can form bonds with other metal atoms, but in
a different way.
In a metal, the electrons in the outer energy levels of
the atoms are not held tightly to individual atoms.
Instead, they move freely among all the ions in the
metal, forming a shared pool of electrons.
Metallic bonds form when metal atoms share
their pooled electrons.
72. Metallic Bonding - Pooling
This bonding affects the properties of metals.
73. Metallic Bonding - Pooling
This bonding affects the properties of metals.
For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of
atoms slide over one another.
74. Metallic Bonding - Pooling
This bonding affects the properties of metals.
For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of
atoms slide over one another.
An ounce of gold can be
stretched into a wire 50
miles long.
75. Metallic Bonding - Pooling
This bonding affects the properties of metals.
For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of
atoms slide over one another.
An ounce of gold can be
stretched into a wire 50
miles long.
76. Metallic Bonding - Pooling
This bonding affects the properties of metals.
For example, when a metal is hammered into sheets or
drawn into a wire, it does not break. Instead, layers of
atoms slide over one another.
A lump of pure gold
the size of a matchbox
can be flattened into a
sheet the size of a tennis
An ounce of gold can be court.
stretched into a wire 50
miles long.
78. Metallic Bonding - Pooling
The pooled electrons tend to hold the atoms together.
79. Metallic Bonding - Pooling
The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct
electricity well.
80. Metallic Bonding - Pooling
The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct
electricity well.
The outer electrons in metal atoms readily move
from one atom to the next to transmit current.
81. Metallic Bonding - Pooling
The pooled electrons tend to hold the atoms together.
Metallic bonding also is the reason that metals conduct
electricity well.
The outer electrons in metal atoms readily move
from one atom to the next to transmit current.
86. Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons
because the number of electrons in their outer levels
makes this difficult.
87. Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons
because the number of electrons in their outer levels
makes this difficult.
Carbon has six electrons,
four of the six electrons are in
its outer energy level.
88. Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons
because the number of electrons in their outer levels
makes this difficult.
Carbon has six electrons,
four of the six electrons are in
its outer energy level.
89. Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons
because the number of electrons in their outer levels
makes this difficult.
Carbon has six electrons,
four of the six electrons are in
its outer energy level.
To obtain a more stable
structure, carbon would either
have to gain or lose four
electrons.
90. Covalent Bonds - Sharing
Some atoms are unlikely to lose or gain electrons
because the number of electrons in their outer levels
makes this difficult.
Carbon has six electrons,
This is difficult
four of the six electrons are in because gaining &
its outer energy level. losing so many
electrons takes
To obtain a more stable
structure, carbon would either
so much energy.
have to gain or lose four The alternative is
electrons. sharing electrons.
92. The Covalent Bond
The chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
93. The Covalent Bond
The chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
Shared electrons are attracted to the nuclei of both
atoms.
94. The Covalent Bond
The chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
Shared electrons are attracted to the nuclei of both
atoms.
They move back and forth between the outer energy
levels of each atom in the covalent bond.
95. The Covalent Bond
The chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
Shared electrons are attracted to the nuclei of both
atoms.
They move back and forth between the outer energy
levels of each atom in the covalent bond.
Each atom has a stable outer energy level some of the
time.
96. The Covalent Bond
The chemical bond that forms between nonmetal
atoms when they share electrons is called a
covalent bond.
Shared electrons are attracted to the nuclei of both
atoms.
They move back and forth between the outer energy
levels of each atom in the covalent bond.
Each atom has a stable outer energy level some of the
time.
Covalently bonded compounds are called molecular
compounds.
100. The Covalent Bond
The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is
called a molecule.
101. The Covalent Bond
The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is
called a molecule.
102. The Covalent Bond
The atoms in a covalent bond form a neutral particle.
The neutral particle formed when atoms share electrons is
called a molecule.
No ions are involved in covalent bonding because no
electrons are gained or lost.
Ionic compounds, such as sodium chloride (NaCl), are
not referred to as molecules, because their basic units are
ions, not molecules.
105. Double and Triple Bonds
Sometimes an atom shares more than one
electron with another atom.
106. Double and Triple Bonds
Sometimes an atom shares more than one
electron with another atom.
When two pairs of electrons are involved in a
covalent bond, the bond is called a double
bond.
121. Double and Triple Bonds
Here is the sharing of three pairs of electrons
between two nitrogen atoms in the nitrogen
molecule.
122. Double and Triple Bonds
Here is the sharing of three pairs of electrons
between two nitrogen atoms in the nitrogen
molecule.
When three pairs of electrons are shared by two
atoms, the bond is called a triple bond.
123. Double and Triple Bonds
Here is the sharing of three pairs of electrons
between two nitrogen atoms in the nitrogen
molecule.
When three pairs of electrons are shared by two
atoms, the bond is called a triple bond.
127. Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
128. Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
The answer is no.
129. Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
The answer is no.
Some atoms have a greater attraction for
electrons than others do.
130. Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
The answer is no.
Some atoms have a greater attraction for
electrons than others do.
Why?????
131. Polar and Nonpolar Molecules
Do atoms always share their electrons equally?
The answer is no.
Some atoms have a greater attraction for
electrons than others do.
Why?????
Some atoms have more protons, therefore more
positive pull on the electrons.
133. Polar and Nonpolar Molecules
Chlorine attracts electrons more strongly than hydrogen
does.
134. Polar and Nonpolar Molecules
Chlorine attracts electrons more strongly than hydrogen
does.
When hydrogen and chlorine covalently bond, the shared
pair of electrons tends to spend more time near the chlorine
atom than the hydrogen atom.
135. Polar and Nonpolar Molecules
Chlorine - 17 protons Hydrogen - 1 proton
Chlorine attracts electrons more strongly than hydrogen
does.
When hydrogen and chlorine covalently bond, the shared
pair of electrons tends to spend more time near the chlorine
atom than the hydrogen atom.
136. Polar and Nonpolar Molecules
Chlorine - 17 protons Hydrogen - 1 proton
Chlorine attracts electrons more strongly than hydrogen
does.
When hydrogen and chlorine covalently bond, the shared
pair of electrons tends to spend more time near the chlorine
atom than the hydrogen atom.
138. Polar and Nonpolar Molecules
The unequal sharing makes one side of the bond more
negative than the other. Such bonds are called polar
bonds.
139. Polar and Nonpolar Molecules
The unequal sharing makes one side of the bond more
negative than the other. Such bonds are called polar
bonds.
A polar bond is a bond in which electrons are
shared unevenly.
140. Polar and Nonpolar Molecules
The unequal sharing makes one side of the bond more
negative than the other. Such bonds are called polar
bonds.
A polar bond is a bond in which electrons are
shared unevenly.
141. Water
The bonds between the oxygen atom and hydrogen
atoms in the water molecule are another example of
polar bonds.
143. “Get Away, Water!”
When water molecules are exposed to a negative
charge, the water molecules line up like magnets
with their positive ends facing the negative
charge.
They are drawn to the negative charge on the
balloon.
Water molecules also are attracted to each other.
This attraction between water molecules accounts
for many of the physical properties of water.
145. “Get Away, Water!”
Molecules that do not have these uneven charges
are called nonpolar molecules.
146. “Get Away, Water!”
Molecules that do not have these uneven charges
are called nonpolar molecules.
Because each element differs slightly in its ability
to attract electrons, the only completely nonpolar
bonds are bonds between atoms of the same
element.
147. “Get Away, Water!”
Molecules that do not have these uneven charges
are called nonpolar molecules.
Because each element differs slightly in its ability
to attract electrons, the only completely nonpolar
bonds are bonds between atoms of the same
element.
One example of a nonpolar bond is the triple bond
in the nitrogen molecule.
148. “Get Away, Water!”
Molecules that do not have these uneven charges
are called nonpolar molecules.
Because each element differs slightly in its ability
to attract electrons, the only completely nonpolar
bonds are bonds between atoms of the same
element.
One example of a nonpolar bond is the triple bond
in the nitrogen molecule.
149. Chemical Shorthand
In medieval times, alchemists were the first to
explore the world of chemistry.
They used symbols to represent elements.
150. Symbols for Atoms
Modern chemists also use symbols to represent
elements.
The symbols are universal.
Each element is represented by a one letter-, two letter-,
or three-letter symbol.
Many symbols are the first letters of the element’s name,
such as H for hydrogen and C for carbon.
Others are the first letters of the element’s name in
another language, such as K for potassium, which
stands for kalium, the Latin word for potassium.
151. Symbols for Compounds
Compounds can be described using element symbols
and numbers. The figure below shows how two
hydrogen atoms join together in a covalent bond.
The resulting hydrogen molecule is represented by the
symbol H2. The subscript 2 means that two atoms of
hydrogen are in the molecule.
153. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
154. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S
155. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S Ag2S
156. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S Ag2S NH3
157. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S Ag2S NH3
H2SO4
158. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S Ag2S NH3
H2SO4 NaOH
159. Chemical Formula
A chemical formula is a combination of chemical
symbols and numbers that shows which elements
are present in a compound and how many atoms of
each element are present.
When no subscript is shown, the number of atoms is
understood to be one.
H2S Ag2S NH3 H
H2SO4 NaOH
160.
161. Question 1
What is the term for an atom which has lost
or gained an electron and therefore has a net
charge?
A. compound
B. ion
C. molecule
D. polar compound
162. Answer
The answer is B. When this
happens to an atom, we say
it has become “ionized.”
163. Question 2
When two or more elements are
chemically bonded to form a
substance, that substance is called a
_______.
164. Answer
A compound is a pure substance
containing two or more elements that
are chemically bonded. An example of
a compound is salt, or sodium
chloride.
165. Question 3
A _______ bond occurs when atoms of
nonmetals share electrons.
A. covalent bond
B. ionic bond
C. metallic bond
D. polar bond
166. Answer
The answer is A. When this type of
bonding happens between metal atoms it
is called pooling.
