Three Types of Bonding (1) Metallic (2) Ionic (3) Covalent
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Three Types of Bonding
(1) Metallic
(2) Ionic
(3) Covalent
Sea of electrons model used to explain bonding between metal atoms; it is also useful in explaining characteristics of metals (they conduct electricity, are maleable, are ductile, etc.)
The valence electrons of metal atoms can be modeled as a sea of electrons.
The model involves a positively charged kernel (nucleus and nonvalence electrons) and valence electrons that are free to move or drift freely from one part of the metal to another. In this model the valence electrons are mobile.
Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged kernel of the metal atom
Metallic Bonding
Metallic Bonds and Metallic Properties• Metals are ductile—that is,
they can be drawn into wires.
7.3
Metallic Bonds and Metallic Properties
• A force can change the shape of a metal. A force can shatter an ionic crystal.
7.3
Formation of Ionic Compounds
•Formation of Ionic Compounds
–What is the electrical charge of an ionic compound?
• Compounds composed of cations and anions are called ionic compounds.•
7.2
Formation of Ionic Compounds
•Formation of Ionic Compounds
–What is the electrical charge of an ionic compound?
• Compounds composed of cations and anions are called ionic compounds.• Although they are composed of ions, ionic compounds are electrically neutral.
7.2
Formation of Ionic Compounds• Aluminum metal and
the nonmetal bromine react to form an ionic solid, aluminum bromide.
7.2
Formation of Ionic Compounds• NaCl is the chemical formula for sodium chloride.
7.2
Properties of Ionic Compounds–Most ionic compounds are crystalline solids at room temperature. –Ionic compounds generally have high melting points.
–Other points to Know?
7.2
–Ionic compounds can conduct an electric current when melted or dissolved in water.
Molecules and Molecular Compounds• In nature, matter takes many forms.
The noble gases, including helium and neon, are monatomic. That means they exist as single atoms. • Represented by symbols: He, Ne, etc)• the noble gases are not molecules
8.1
Molecules and Molecular Compounds
• A molecule is a neutral group of atoms joined together by covalent bonds. Air contains oxygen molecules.• A diatomic molecule is a molecule consisting of two
atoms. An oxygen molecule is a diatomic molecule.
8.1
Molecules and Molecular Compounds
Some elements do exist as diatomic molecules. Hydrogen H2 (g)Oxygen O2 (g) Fluorine F2 (g)Bromine Br2 (l)Iodine I2 (s)Nitrogen N2 (g) Chlorine Cl2 (g)
8.1
(note these are molecules but they are not compounds)
Molecular Formulas• Formulas of Some Molecular Compounds
8.1
Bond Polarity and Polarity of Molecules
• Bond Polarity can be predicted by differences in Electronegativity (Use table S)
• Molecules with Polar Bonds may be either polar or nonpolar
• Use SNAP to predict molecule polarity
• Examples CH4, CO2, H2, are all nonpolar molecules
• (H2O, HCl, NH3 are all polar molecules
Molecules and Molecular Compounds8.1
Molecular Formulas8.1
•Chapter 8: Covalent Bonding
Types of Bonding ?
(review)
Metallic Bonding
(ch 7)
BONDING
•Sea of electrons model used to explain bonding in metals•Kernel & delocalized mobile valence electrons
Metallic Bonding
(ch 7)
Ionic Bonding
(ch 7)
BONDING
Electrostatic attraction of negatively and positively charged ions
Can be formed as a result of the transfer of electrons between metal and nonmetal atoms to form cations and anions
Metallic Bonding
(ch 7)Ionic
Bonding (ch 7)
Covalent Bonding
(ch 8)
•Electrons are shared between atoms•Covalent bonds may be nonpolar (equal sharing of electrons) or polar (unequal sharing of electrons )
BONDING
8.2
The Octet Rule in Covalent Bonding
•The Octet Rule in Covalent Bonding
–In covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases.
Single Covalent Bonds• The halogens form single covalent bonds in their
diatomic molecules. Fluorine is one example.
8.2
Single Covalent Bonds• The hydrogen and oxygen atoms attain noble-gas
configurations by sharing electrons.
8.2
Single Covalent Bonds• The ammonia molecule has one unshared pair of
electrons.
8.2
Single Covalent Bonds• Methane has no unshared pairs of electrons.
8.2
Section Assessment
for Conceptual Problem 8.1
8.2
Double and Triple Covalent Bonds
•Double and Triple Covalent Bonds– How do atoms form double or triple
covalent bonds?
–Atoms form double or triple covalent bonds if they can attain a noble gas structure by sharing two pairs or three pairs of electrons.
8.2
Double and Triple Covalent Bonds• A bond that involves two shared pairs of electrons is a
double covalent bond. (ex: O2 has a double covalent bond between the two oxygen atoms)
• A bond formed by sharing three pairs of electrons is a triple covalent bond. (ex. N2 has a triple covalent bond between the two nitrogen atoms)
Double and Triple Covalent Bonds
• O2 molecule: Each oxygen atom has two unshared pair of electrons. N2 molecule: Each nitrogen has one pair of unshared electrons• Lewis dot structure of O2 and N2
8.2
8.2
Double and Triple Covalent Bonds• Carbon dioxide gas is soluble in water and is used to
carbonate many beverages. A carbon dioxide molecule has two carbon-oxygen double bonds.
Coordinate Covalent Bonds
• A polyatomic ion, such as NH4+, is a tightly bound group
of atoms that has a positive or negative charge and behaves as a unit. One of its bonds is a coordinate covalent bond.• Most plants need nitrogen that is already combined in
a compound to grow.
8.2
Metallic Bonding
(ch 7)
Ionic Bonding (ch 7)
Covalent Bonding
(ch 8)
Bonding in:NaCl ?HCl ? H2O ?
Bonding in ionic compounds containing polyatomic ions:Na2CO3 ?BaSO4 ? NH4Cl ?
Polyatomic Ions
•Polyatomic Ions– What are the two endings of the names of most
polyatomic ions? – (Hint: use Table E)
9.1
Polyatomic Ions• These models show the structures of four common
polyatomic ions.
9.1
Polyatomic Ions• Sodium hydrogen carbonate can relieve an upset
stomach.
9.1
• Carbon and oxygen combine to form carbon monoxide (CO) and carbon dioxide (CO2), but these two invisible gases are very different.
9.3 Naming Binary Molecular Compounds
•A prefix in the name of a binary molecular compound tells how many atoms of an element are present in each molecule of the compound.
9.3 Naming Binary Molecular Compounds
You MUST know these Prefixes
•Some guidelines for naming binary molecular compounds:»Name the elements in the order listed in the
formula.
»Use prefixes to indicate the number of each kind of atom.
»Omit the prefix mono- when the formula contains only one atom of the first element in the name.
»The suffix of the name of the second element is -ide.
9.3 Naming Binary Molecular Compounds
– 1. Which of the following compounds is named INCORRECTLY?• CS2, carbon disulfide
• BCl3, boron trichloride
• IF7, iodine heptafluoride
• PCl5, phosphorus hexachloride
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