BONDING

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BONDING

• Chapters 4 12

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Ionic vs. Covalent Bonds

• Ionic
• result from the attraction between opposite
  charges of ions

• Covalent
• result from sharing of electrons between atoms

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The Octet Rule

• Atoms will gain, lose, or share electrons to
  achieve a noble gas configuration
• If the atom has 1-3 valence electrons, it will
  LOSE those electrons and become a positive ion
  (CATION).
• If the atom has 5-7 valence electrons, it will
  GAIN electrons until it has EIGHT, becoming a
  negative ion (ANION).

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Practice Forming Ions

• Complete the table below for each of the atoms

ATOM of Valence Electrons GAIN or LOSE electrons? ION CATION or ANION?
Magnesium
Chlorine
Potassium
Nitrogen
Oxygen
Lithium
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What are Ionic Compounds?

• Compound made of only ions
• Formed by the gaining or losing of electrons
• Typically between a metal and a non-metal
• Ionic Bonding
• A positively charged ion (anion) will be
  attracted to and will form a bond with a
  negatively charged ion (cation)
• The ions will exchange electrons to achieve their
  charge (and reach the noble gas configuration)

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Properties of Ionic Compounds

• Overall neutral
• High melting points
• Generally brittle solids
• Dissolve in water to form electrolytes

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Types of Ions

• Monoatomic cations ( positive)
• Monoatomic anions (- negative)
• Polyatomic ions

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Monoatomic cations

• Positively charged, ions formed from ONE atom
• To name the cation, simply add the word ion
  after the elements name
• Li Lithium ion
• Mg2 Magnesium ion
• Some atoms have the ability to form multiple ions
  (most of these are transition metals)
• To name, simply name the element, indicate the
  charge in roman numerals and then add the word
  ion
• Fe2 Iron (II) ion
• Fe3 Iron (III) ion

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Monoatomic anion

• Negatively charged, ions formed from ONE atom
• To name the anion, replace the ending of the
  elements name with -ide
• F - Fluorine ? Fluoride
• O -2 Oxygen ? Oxide

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Monoatomic ion Practice

• Complete the table below for each of the atoms

ATOM ION CATION or ANION? NAME of ION
Magnesium
Chlorine
Potassium
Nitrogen
Oxygen
Lithium
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Polyatomic ions

• Multiple atoms that, TOGETHER, carry a charge.

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IONIC COMPOUNDS

• WRITING FORMULAS
• Write the symbol for the cation first.
• Write the symbol for the anion second.
• Add subscripts so the charges equal zero when
  added.
• NAMING COMPOUNDS
• Write the name of the cation unchanged first.
• Write the root of the anion with the ide ending.

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How do I write a formula for an ionic compound?

• Use the CRISS-CROSS METHOD
• Write the ions in order of metal then nonmetal
• Take the ionic charge number (written as the
  superscript) of each element and criss cross it
  to the subscript of the other element

2
-1
Ca
Cl
Ca_Cl_
2
1
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Ionic Compound Formula Practice

• Write the ionic formula for the following ions
• Mg2 with P-3
• B3 with S-2
• Li1 with S-2
• Ga3 with Se-2
• B3 with At-1

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How do I name ionic compounds?

• Compounds are named from the ions that form them
• The first element (metal) keeps its name
• If its a transition metal, you must use a roman
  numeral to indicate its charge
• The second element (nonmetal) keeps the first
  syllable of its name and the ending is changed to
  -ide

NaCl Sodium Chloride
Fe2O3
Since Fe is a transition metal, you must find
its charge UNCRISS CROSS
Fe2O3
-2
3
Iron (III)
Oxide
Fe
O
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Ionic Compound Naming Practice

• Write the ionic compound name for the following
• BaCl2
• NaF
• Ag2O
• CuBr
• CuBr2

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Binary Ionic Compounds

• Binary Compound
• Ionic compound composed of two atoms
• Formula Unit
• Smallest representative unit

ATOMS FORMULA NAME of COMPOUND
Magnesium Chlorine IONS
Potassium Nitrogen IONS
Lithium Oxygen IONS
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Tertiary Ionic Compounds

• Tertiary Compound
• Ionic compound composed of three atoms

IONS FORMULA NAME of COMPOUND
K and NO3-
Mg2 and OH-
Cu2 and PO4-3
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Hydrates
PREFIX NUMBER
mono- 1
di- 2
tri- 3
tetra- 4
penta- 5
hexa- 6
hepta- 7
octa- 8
nona- 9
deca- 10

• Ionic compounds that absorb water into their
  solid structures
• CuSO4 ? 5H2O

Copper Sulfate Pentahydrate
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Covalent Compounds

• Covalent Bond
• Formed by the sharing of electrons
• Molecule
• Smallest representative unit
• Molecular Compound
• Compounds composed of molecules
• Molecular Formula
• Shows the kind and numbers of atoms present in a
  molecule

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Properties of Covalent Compounds

• made of two nonmetals
• low melting and boiling points
• solid, liquid, or gas at room temp.
• do not dissociate in water

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Naming Covalent Compounds

• Write the less electronegative element first.
• Write the root of the more electronegative
  element with the -ide ending second.
• REVIEW Electronegativity
• - the attraction to electrons involved
  in a chemical bond
• Add prefixes to both indicating the number of
  atoms of each element

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Exceptions when Naming Covalent Compounds

• Exceptions
• Do not use mono-with the first element in the
  compound
• Prefixes are sometimes shortened.
• CO (Carbon Monoxide)
• Chemist use common names for some compounds other
  than the formal names.
• NH3 (Ammonia)

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Naming Covalent Compounds
FORMULA NAME of COMPOUND
CO
CO2
CO3-2
C2O4-2
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Types of Covalent Bonds

• Polar Covalent Bond
• one atom in a molecule is significantly more
  electronegative
• causes a slight positive and negative charge on a
  molecule.
• Nonpolar Covalent Bond
• electrons are shared equally
• Electronegativity Differences Bond Type
• ? 0.4 nonpolar
• 0.5-1.9 polar
• ? 2.0 ionic

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Covalent Bonds

• Single Covalent Bond
• two atoms share 1 pair of electrons
• Double Covalent Bond
• two atoms share 2 pair of electrons
• Triple Covalent Bond
• two atoms share 3 pair of electrons

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Acid

• A molecular substance that dissolves in water to
  produce a hydrogen ion
• Acts like an ionic compound because they break
  down into cations and anions in water
• Produces a characteristic anion for which it is
  named.
• If the anion ends with
• -ide (i.e. chloride or fluoride)
• Add the prefix hydro- and change the ending to
  ic and add the word acid
• -ate (i.e. phosphate or sulfate)
• Change the ending to ic and add the word acid
• -ite (i.e. sulfite and phosphite)
• Change the ending to ous and add the word acid