6.1 Ionic Bonding
Stable Electron Configurations
When is an atom unlikely to react?
When the highest occupied energy level of
an atom is filled with _________________,
the atom is stable and not likely to react.
6.1 Ionic Bonding
Stable Electron Configurations
The chemical properties of an element depend
on the number of ______________________.
An electron _________ diagram is a model of
an atom in which each dot represents a
valence electron. The symbol in the center
represents the nucleus and all the other
electrons in the atom.
6.1 Ionic Bonding
Stable Electron Configurations
6.1 Ionic Bonding
Stable Electron Configurations
Noble gases are the most ____________
elements.
• The highest occupied energy level of a
noble gas atom is completely ________.
• The noble gases have stable electron
configurations with ____ valence electrons
(two electrons in the case of helium).
• Elements tend to react to achieve electron
configurations ______________ to those
of noble gases.
6.1 Ionic Bonding
Ionic Bonds
What is one way in which elements can
achieve stable electron configurations?
Some elements achieve stable electron
configurations through the ___________ of
electrons between atoms.
6.1 Ionic Bonding
Ionic Bonds
Transfer of Electrons
• A chlorine atom has ______ electron fewer
than an argon atom. _________________
one electron would give chlorine a stable
configuration.
• A sodium atom has ______ more electron
than a neon atom. ________________
one electron would give sodium a stable
configuration.
6.1 Ionic Bonding
Ionic Bonds
When sodium reacts with chlorine, an electron is
transferred from each sodium atom to a chlorine
atom. Each atom ends up with a __________
stable electron arrangement than it had before the
transfer.
6.1 Ionic Bonding
Ionic Bonds
Formation of Ions
When an atom gains or loses an electron, the number
of protons is no longer ____________ to the number
of electrons.
• The charge on the atom is not balanced, and the
atom is not neutral.
• An atom that has a net positive or negative
electric charge is called an ______.
• The charge on an ion is represented by a plus or
a minus sign.
6.1 Ionic Bonding
Ionic Bonds
The ion that forms when a chlorine atom gains an
electron has 17 protons and 18 electrons.
• This ion has a charge of 1–.
• The symbol for the ion is written Cl1–, or Cl–
for short.
• An ion with a negative charge is an
________.
• Anions like the Cl– ion are named by using
part of the element name plus the suffix –ide.
Thus, Cl– is called a chloride ion.
6.1 Ionic Bonding
Ionic Bonds
A sodium ion has 11 protons and 10 electrons.
• The sodium ion has a charge of 1+.
• The symbol for the ion is written Na1+, or Na+
for short.
• An ion with a positive charge is a
___________.
• A cation uses the element name, as in the
sodium ion.
6.1 Ionic Bonding
Ionic Bonds
Formation of Ionic Bonds
A particle with a negative charge will attract a
particle with a positive charge.
• A __________________________ is the force
that holds atoms or ions together as a unit.
• An _________________________ is the force
that holds cations and anions together. An ionic
bond forms when electrons are transferred from
one atom to another.
6.1 Ionic Bonding
Ionic Compounds
How does the structure of an ionic
compound affect its properties?
Solids whose particles are arranged in a
___________ structure are called
_____________.
The properties of an ionic compound can be
explained by the strong _________________
among ions within a crystal lattice.
6.1 Ionic Bonding
Ionic Compounds
Compounds that contain ionic bonds are ionic
compounds, which can be represented by chemical
formulas.
• A _________________________ is a notation
that shows what elements a compound contains
and the ratio of the atoms or ions of those
elements in the compound.
• The chemical formula for sodium chloride, NaCl,
indicates one sodium ion for each chloride ion in
sodium chloride.
6.1 Ionic Bonding
Ionic Compounds
What is the chemical formula for magnesium chloride?
A magnesium atom cannot reach a stable electron configuration by
reacting with just one chlorine atom. It must transfer electrons to two
chlorine atoms. After the transfer, the charge on the magnesium ion is
2+ and its symbol is Mg2+.
6.1 Ionic Bonding
Ionic Compounds
The formula for magnesium
chloride is MgCl2. The ____
written to the right and slightly
below the symbol for chlorine
is used to show the relative
numbers of atoms of the
elements present.
Magnesium chloride is used
to control dust on unpaved
roads.
6.1 Ionic Bonding
Ionic Compounds
Properties of Ionic Compounds
The properties of sodium chloride are typical of ionic
compounds.
• Sodium chloride has a
_______________________ (801°C).
• Solid sodium chloride is a ________ conductor
of electric current. When melted, it is a good
conductor of electric current.
• Sodium chloride crystals __________ when
struck with a hammer.
6.1 Ionic Bonding
Ionic Compounds
The arrangement of particles in a substance is the
result of two opposing factors: the attractions among
particles in the substance and the kinetic energy of
the particles.
• The stronger the attractions among the particles,
the more kinetic energy the particles must have
before they can separate.
• Ionic compounds have ___________ attractions
between particles and high melting points.
6.1 Ionic Bonding
Assessment Questions
1. When is an atom stable?
a. when its electrons are evenly distributed through its
energy levels
b. when its lowest occupied energy level is filled with
electrons
c. when its highest unoccupied energy level is filled with
electrons
d. when its highest occupied energy level is filled with
electrons
6.1 Ionic Bonding
Assessment Questions
2. Which description applies to an element that has
two valence electrons?
a.
b.
c.
d.
reactive metal
nonreactive metal
reactive nonmetal
nonreactive nonmetal
6.1 Ionic Bonding
Assessment Questions
3. How do sodium and chlorine both achieve stable
electron configurations when they react?
a. An electron is transferred from the sodium atom to the
chlorine atom.
b. An electron is transferred from the chlorine atom to the
sodium atom.
c. Both atoms gain one electron.
d. Both atoms lose one electron.
6.1 Ionic Bonding
Assessment Questions
4. Why do ionic compounds tend to have high melting points?
a. Ionic compounds contain more than one element, which causes a
high melting point.
b. Ionic compounds cannot absorb energy efficiently because they
contain ions.
c. An ionic compound contains metal atoms that raise its melting
point.
d. A strong electrical attraction means ions require a lot of energy to
move apart.
6.1 Ionic Bonding
Assessment Questions
1. The ratio of aluminum ions to chloride ions in
aluminum chloride (AlC13) is 3:1.
True
False
6.1 Ionic Bonding
Covalent Bonds
How are atoms held together in a
__________________ bond?
The attractions between the
__________________ electrons and the
protons in each nucleus hold the atoms
together in a __________________ bond.
A __________________ bond is a chemical
bond in which two atoms __________________
a pair of valence electrons.
6.1 Ionic Bonding
Covalent Bonds
Sharing Electrons
A hydrogen atom has one electron. If it had two
electrons, it would have the same electron
configuration as a helium atom.
Two hydrogen atoms can achieve a stable
electron configuration by sharing their
electrons and forming a covalent bond.
When two atoms share ______ pair of
electrons, the bond is called a _______ bond.
6.1 Ionic Bonding
Covalent Bonds
There are several ways to show a covalent
bond.
• In the electron ____ model, the bond is shown by
a pair of dots in the space between the symbols
for the hydrogen atoms.
• In the structural formula, the pair of dots is
replaced by a line.
6.1 Ionic Bonding
Covalent Bonds
Molecules of Elements
Two hydrogen atoms bonded together form a
unit called a molecule.
A ______________ is a neutral group of
atoms that are joined together by one or more
covalent bonds.
6.1 Ionic Bonding
Covalent Bonds
Many nonmetal
elements exist as
diatomic molecules.
___________ means
“two atoms.”
6.1 Ionic Bonding
Covalent Bonds
Multiple Covalent Bonds
When two atoms share ______ pairs of
electrons, the bond is called a ___________
bond. When two atoms share _____ pairs of
electrons, the bond is called a ________ bond.
Nitrogen has five valence electrons. When the
atoms in a nitrogen molecule (N2) share three
pairs of electrons, each atom has eight valence
electrons. Each pair of shared electrons is
represented by a long dash in the structural
formula NN.
6.1 Ionic Bonding
Unequal Sharing of Electrons
What happens when atoms don’t share
electrons ___________?
What factors determine whether a molecule
is __________?
6.1 Ionic Bonding
Unequal Sharing of Electrons
When atoms form a _______ covalent bond,
the atom with the greater attraction for
electrons has a partial negative charge. The
other atom has a partial positive charge.
The type of atoms in a molecule and its
shape are factors that determine whether a
molecule is ______ or ______________.
6.1 Ionic Bonding
Unequal Sharing of Electrons
Except for noble gases, elements on the right
of the periodic table tend to have a _________
attraction for electrons than elements on the
left.
Elements at the top of a group tend to have a
greater attraction for electrons than elements
at the bottom of a group have.
6.1 Ionic Bonding
Unequal Sharing of Electrons
Polar Covalent Bonds
In a molecule of an element, the atoms that
form covalent bonds have the same ability to
attract an electron. Shared electrons are
attracted _________ to the nuclei of both
atoms.
In a molecule of a compound, electrons may
not be shared ____________.
6.1 Ionic Bonding
Unequal Sharing of Electrons
A covalent compound forms when hydrogen
reacts with chlorine.
• A chlorine atom has a greater _____________
for electrons than a hydrogen atom does.
• In a hydrogen chloride molecule, the shared
electrons spend more time near the chlorine
atom than near the hydrogen atom.
• A covalent bond in which electrons are not
shared equally is called a _________ covalent
bond.
6.1 Ionic Bonding
Attraction Between Molecules
How do attractions between polar molecules
compare to attractions between nonpolar
molecules?
Attractions between polar molecules are
_________________ than attractions
between nonpolar molecules.
6.1 Ionic Bonding
Attraction Between Molecules
Dashed lines
represent attractions
between partially
positive hydrogen
atoms and partially
negative oxygen
atoms. The symbols
– and + are used to
indicate a partial
charge.
6.1 Ionic Bonding
Attraction Between Molecules
Attractions among nonpolar molecules are
______________ than attractions among polar
molecules, but they do exist.
Attractions among nonpolar molecules explain
why carbon dioxide can exist as dry ice and
why nitrogen can be stored as a liquid at low
temperatures and high pressures.
6.1 Ionic Bonding
Assessment Questions
1. What attractions hold two atoms in a molecule
together?
a. attraction between ions with opposite charges
b. attraction between the nuclei of the atoms and shared
electrons
c. attraction between each nucleus and the electrons of
the other atom
d. attraction between the molecule and other molecules
6.1 Ionic Bonding
Assessment Questions
2. What determines whether a molecule is polar?
a.
b.
c.
d.
type of atoms and shape of molecule
mass of atoms and number of valence electrons
type and mass of atoms
ionization energy and number of covalent bonds
6.1 Ionic Bonding
Assessment Questions
1. Why does water have a much higher boiling point
than methane?
a. Methane molecules are more polar, so its molecules
have stronger attractive forces.
b. Partial charges on the polar water molecules increase
attractive forces between molecules.
c. A water molecule has much more mass than a methane
molecule, so water has a higher boiling point.
d. Water has a higher boiling point because its molecules
do not contain carbon atoms.
6.1 Ionic Bonding
Describing Ionic Compounds
What information do the name and formula
of an _______________ compound provide?
The name of an ionic compound must
_______________ the compound from other
ionic compounds containing the same
elements. The formula of an ionic compound
describes the ____________ of the ions in
the compound.
6.1 Ionic Bonding
Describing Ionic Compounds
Binary Ionic Compounds
A compound made from only _____ elements
is a binary compound.
Naming binary ionic compounds, such as
sodium chloride and cadmium iodide, is easy.
The names have a predictable pattern: the
name of the _________ followed by the name
of the __________.
6.1 Ionic Bonding
Describing Ionic Compounds
This table lists
eight common
anions. The name
of an anion is
formed by adding
the
suffix –ide to the
stem of the name
of the nonmetal.
6.1 Ionic Bonding
Describing Ionic Compounds
Metals With Multiple Ions
Many __________________ metals form more
than one type of ion. Many paint pigments
contain compounds of transition metals.
6.1 Ionic Bonding
Describing Ionic Compounds
The table shows a copper(I) ion with a 1+ charge
and a copper(II) ion with a 2+ charge. These ion
names can distinguish red copper(I) oxide from
black copper(II) oxide.
• The formula for “copper one oxide” is Cu2O
because it takes two Cu1+ ions to balance the
charge on an O2– ion.
• The formula for “copper two oxide” is CuO
because it takes only one Cu2+ ion to
balance the charge on an O2– ion.
6.1 Ionic Bonding
Describing Ionic Compounds
Polyatomic Ions
This electron dot diagram models
a group of atoms that includes one
nitrogen atom and four hydrogen
atoms.
The ammonium ion loses a
valence electron as it forms. This
loss leaves only 10 electrons to
balance the charge on 11 protons,
so the ion has a positive charge.
6.1 Ionic Bonding
Describing Ionic Compounds
A covalently bonded group of atoms that has a
positive or negative charge and acts as a
unit is a ___________________ ion. Most simple
polyatomic ions are anions.
6.1 Ionic Bonding
Describing Ionic Compounds
Writing Formulas for Ionic Compounds
• Use the name of an ionic compound to
write its formula. The symbol of the cation
is first, followed by the symbol of the anion.
• Use subscripts to show the ratio of the ions
in the compound.
• Parentheses are used with the subscript for
polyatomic ions. The formula for iron(III)
hydroxide is Fe(OH)3.
6.1 Ionic Bonding
Describing Ionic Compounds
Because all compounds are neutral, the total
charges on the cations and anions must add
up to zero. Suppose an atom that gains two
electrons, such as sulfur, reacts with an atom
that loses one electron, such as sodium.
• There must be two sodium ions (Na+) for each
sulfide ion (S2–).
• The formula for sodium sulfide is Na2S. The 2–
charge on one sulfide ion is balanced by the 1+
charges on two sodium ions.
6.1 Ionic Bonding
Describing Molecular Compounds
What information do the name and formula
of a ________________ compound provide?
The name and formula of a
________________ compound describe the
type and number of atoms in a molecule of
the compound.
6.1 Ionic Bonding
Describing Molecular Compounds
Naming Molecular Compounds
• The general rule is that the most metallic element
appears first in the name. These elements are
farther to the _______ in the periodic table.
• If both elements are in the same group, the more
metallic element is closer to the bottom of the group.
• The name of the second element is changed to end
in the suffix -ide, as in carbon dioxide.
6.1 Ionic Bonding
Describing Molecular Compounds
There may be more than one
molecular compound that can exist
with the same two elements.
The Greek prefixes in the table are
used to name molecular
compounds. The prefix octa-means
“eight,” as in the eight tentacles of
an octopus.
6.1 Ionic Bonding
Describing Molecular Compounds
Two compounds that contain nitrogen and
oxygen have the formulas N2O4 and NO2.
• The name of the compound with the formula
N2O4 is dinitrogen tetraoxide.
• The name for the compound with the formula
NO2 is mononitrogen dioxide. The prefix monooften is not used for the first element in the
name, so a more common name is nitrogen
dioxide.
6.1 Ionic Bonding
Describing Molecular Compounds
Writing Molecular Formulas
To write the formula for a molecular compound, write
the symbols for the elements in the order the
elements appear in the name.
• The prefixes indicate the number of atoms of
each element in the molecule.
• The prefixes appear as subscripts in the
formulas.
• If there is no prefix for an element in the name,
there is only one atom of that element in the
molecule.
6.1 Ionic Bonding
Describing Molecular Compounds
What is the formula for diphosphorus
tetrafluoride?
• Because the compound is molecular, look for
elements on the right side of the periodic table.
• Phosphorus has the symbol P. Fluorine has the
symbol F.
• Di- indicates two phosphorus atoms, and tetraindicates four fluorine atoms.
• The formula for the compound is P2F4.
6.1 Ionic Bonding
Assessment Questions
1. Which of these formulas describes a binary ionic
compound?
a.
b.
c.
d.
O2
MgCl2
NO2
Fe(OH)3
6.1 Ionic Bonding
Assessment Questions
2. What is the correct name for CCl4?
a.
b.
c.
d.
carbon(IV) chloride
carbon tetrachlorine
carbon tetrachloride
monocarbon tetrachloride
6.1 Ionic Bonding
Metallic Bonds
What are the forces that give a ___________
its structure as a solid?
The _____________ in a metal form a lattice
that is held in place by strong metallic bonds
between the cations and the surrounding
____________________________.
6.1 Ionic Bonding
Metallic Bonds
Metal atoms achieve stable electron
configurations by __________________
electrons. What happens if there are no
nonmetal atoms available to accept the
electrons?
In a metal, valence electrons are free to
_________ among the atoms. In effect, the
metal atoms become cations surrounded by a
pool of shared electrons.
6.1 Ionic Bonding
Metallic Bonds
A _______________ bond is the attraction
between a metal cation and the shared
electrons that surround it.
Although the _______________ are moving
among the atoms, the total number of electrons
does not change. So, overall, the metal is
neutral.
6.1 Ionic Bonding
Explaining Properties of Metals
How do _______________ bonds produce
some of the typical properties of metals?
The ________________ of electrons within a
metal lattice explains some of the properties
of metals.
6.1 Ionic Bonding
Explaining Properties of Metals
The mobility of electrons within metals affects
the properties of metals. The ability to
_____________ an electric _____________
and _____________________ are two
important properties of metals.
A metal has a built-in supply of charged
particles that can flow. An electric current can
be carried through a metal by the free flow of
the shared electrons.
6.1 Ionic Bonding
Explaining Properties of Metals
In a metal, cations are surrounded by shared
valence electrons. If a metal is struck, the ions
_____________ to new positions, but the ions are
still surrounded by electrons.
Hammer strikes metal.
Metal changes shape
but does not break.
6.1 Ionic Bonding
Alloys
How are the properties of __________
controlled?
Scientists can design alloys with specific
properties by varying the types and amounts
of elements in an alloy.
An _____________ is a mixture of two or more
elements, at least one of which is a metal.
Alloys have the characteristic properties of
__________________.
6.1 Ionic Bonding
Alloys
Steel Alloys
Steel is an alloy of iron that contains small
quantities of carbon, ranging from less than 0.2
percent to about 3 percent by mass.
The smaller carbon atoms fit in the spaces
between the larger iron atoms in the lattice.
The carbon atoms form bonds with neighboring
iron atoms. These bonds make the lattice
harder and stronger than a lattice that contains
only iron.
6.1 Ionic Bonding
Alloys
The properties of steel depend on which elements
in addition to iron and carbon are used to make
the steel and how much of those elements are
included.
• Stainless steels contain more than 10 percent
chromium by mass, but almost no carbon.
• Stainless steels are durable and do not rust.
• Stainless steels are more brittle than steels with
more carbon.
6.1 Ionic Bonding
Assessment Questions
1. What force holds the atoms of a metal together?
a. the attraction of a positively charged atom to a
negatively charged atom
b. the sharing of electrons between two atoms
c. the gravitational force between dense metal atoms
d. the attraction between metal cations and a pool of
shared electrons
6.1 Ionic Bonding
Assessment Questions
2. Why are solid metals good conductors of electric
current?
a. Metals are good conductors because they can be drawn
into wires.
b. Metals are good conductors because they are solids at
room temperature.
c. The nuclei of metal atoms can move easily because
they repel one another.
d. Shared electrons are able to flow freely through the
metal.
6.1 Ionic Bonding
Assessment Questions
1. The properties of bronze depend on the ratio of
iron, carbon, and small amounts of other elements
in the alloy.
True
False