6.1 Ionic Bonding
CHAPTER 6: CHEMICAL BONDS
STABLE ELECTRON CONFIGURATIONS
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If highest energy level of an atom is filled with e-, the
atom is stable and not likely to react
Chemical properties of an element depend on the
number of valence electrons
Electron (Lewis) dot diagram = model in which each
dot represents a valence electron
STABLE ELECTRON CONFIGURATIONS
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Highest energy level of a noble gas atom is
completely filled
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Noble gases have stable electron
configurations with 8 valence electrons (two
electrons in helium).
Elements tend to react to get electron
configurations similar to noble gases
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CHEMICAL BONDING
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http://www.youtube.com/watch?v=_M9khs87xQ8
CHEMICAL BONDING
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Elements can get a stable electron configuration by
transferring of electrons
Ex: A chlorine atom has one electron fewer than
an argon atom, adding one electron would give
chlorine a stable configuration
Ex: A sodium atom has one more electron than
a neon atom, removing one electron would give
sodium a stable configuration.
CHEMICAL BONDING
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When sodium reacts with chlorine, an
electron is transferred from sodium atom to
chlorine atom
Each atom ends up with a more stable
electron arrangement than it had before
transfer
CHEMICAL BONDS
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Electron moves from Na to CL
FORMATION OF IONS
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Ionic Bonds = transfer of electrons
When an atom gains or loses an electron, the number
of protons does not equal number of electrons
Charge on the atom is not balanced, and atom is not neutral
 Ion = Atom that with positive or negative charge
 Charge on an ion is represented by a plus or a minus sign
 Negative charge = anion
 Positive charge = cation
IONIC BONDS
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Ex: Ion that forms when a chlorine atom gains an
electron has 17 protons and 18 electrons
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This ion has a charge of 1–.
The symbol for the ion is written Cl1–, or Cl– for short.
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.
IONIC BONDS
Sodium ion has 11 protons and 10 electrons.
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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 cation.
A cation uses the element name, as in the sodium ion.
FORMATION OF IONIC BONDS
A particle with a negative charge will attract a particle
with a positive charge
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Chemical bond = force that holds atoms or ions together as
a unit
Ionic bond =force that holds cations and anions together,
forms when electrons are transferred from one atom to
another (metal and non-metal)
IONIZATION ENERGY
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Cations (+) form when electrons gain enough energy to
escape from atoms
Energy allows electrons to overcome the attraction of the
protons in the nucleus
Ionization energy = of energy used to remove an electrons
The lower the ionization energy, the easier it is to remove an
electron from an atom
Ionization Energy
IONIC COMPOUNDS
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Compounds that contain ionic bonds are ionic
compounds, can be represented by chemical formulas
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Chemical formula = shows what elements are in a
compound, and how many of each
Ex: Chemical formula for sodium chloride, NaCl, indicates
one sodium ion for each chloride ion in sodium chloride
BINARY IONIC COMPOUNDS
Compound made from only two elements is a binary
compound
The names have a predictable pattern:
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The name of the cation followed by the name of the anion.
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Examples: sodium chloride
DESCRIBING IONIC COMPOUNDS
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Formula of an ionic compound describes the ratio of the ions in
the compound
2 different compounds of copper and oxygen are below
Has to be at least two names to distinguish red copper oxide
from black copper oxide.
POLYATOMIC IONS
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Polyatomic ion = covalently bonded group of atoms that has a
positive or negative charge
Most simple polyatomic ions are anions
Ionic Compounds
What is the chemical formula for magnesium chloride?
Ionic Compounds
What is the chemical formula for magnesium chloride?
MgCl2
NAMING IONIC COMPOUNDS
Write the name of the metal first and then the
nonmetal.
2. Add an -ide ending to the non-metal
3. Use Roman Numerals to indicate charge on a
transition metal
 Ionic compounds involving polyatomic ions
follow the same basic rule:
1. Write the name of the metal first,
2. Then the name of the polyatomic anions
1.
Section 6.2 Covalent Bonds
CHAPTER 6: BONDING
COVALENT BOND
Sharing of valence electrons
 Non-metal and Non-metal
 Attraction between shared electrons and the
protons in each nucleus hold the atoms
together in a covalent bond
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COVALENT BOND
COVALENT BOND
SHARING ELECTRONS
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When two atoms share one pair of electrons,
the bond is called a single bond
Hydrogen atom has one electron, if 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
MOLECULES OF ELEMENTS
Molecule = neutral group of atoms that are
joined together by one or more covalent bonds
 Many nonmetal elements exist as diatomic
molecules
 Diatomic means “two atoms”
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MEMORY TRICK:
Br-I-N-Cl-H-O-F
Brinclhof
Sounds like a German name.
There’s also:
I Brought Clothes For Our New Hamster
… either way…
DIATOMIC MOLECULES
Bromine:
Iodine:
Nitrogen:
Chlorine:
Hydrogen:
Oxygen:
Fluorine:
MULTIPLE COVALENT BONDS
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2 pairs of electrons shared = double bond
3 pairs of electrons shared = triple 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
UNEQUAL SHARING OF ELECTRONS
Polar covalent bond = atom with the greater
attraction for electrons has a partial negative
charge
 Other atom has a partial positive charge
 Happens because the e- are closer to one atom
than the other (one atom attracts e- more)
 Type of atoms in a molecule and its shape are
factors that determine whether a molecule is
polar or nonpolar
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UNEQUAL SHARING OF ELECTRONS
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Except for noble gases, elements on the right of
the periodic table tend to have a greater
attraction for electrons than elements on the
left
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Elements at the top of a group tend to have a
greater attraction for electrons than elements
at the bottom of a group have.
POLAR COVALENT BOND
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Covalent bonds= atoms attract electrons
equally and are shared equally
ATTRACTION BETWEEN MOLECULES
Attractions between polar molecules are
stronger than attractions between nonpolar
molecules
 Bonds between polar molecule are stronger
than non polar
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NAMING COVALENT BONDS
Prefixes tell you how many of each atom you have
 Prefix goes in front of the element name
 Mono- 1
 Di -2
 Tri – 3
 Tetra -4
 Penta – 5
 Hexa – 6
 Hepta – 7
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