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Do you have a favorite chemical or a
chemical you want to learn more about?
Ponder on this for a minute or two. List this
chemical on your paper as the warm-up and
let’s see how today’s lesson exposes some
things about your chemical.
Chemical Bonds
Ionic & Covalent
Bonding
Bond Polarity &
Electronegativity
Lewis Structures
and Kekule’
Structures
E.Q.: How do I compare and contrast types of chemical
bonds?
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When two or more atoms or ions are
strongly attached to each other.
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There are three types:
1. Ionic Bonds: Transfer of electrons.
2. Covalent Bonds: Sharing of electrons.
3. Metallic Bonds: Atoms in metal are bonded to
several neighboring atoms.
Chemical symbol represents the nucleus and core
electrons of the atom.
 Dots around the symbol represent valence electrons.
 First four dots are placed singly on each side of
chemical symbol.
 Lewis symbols are used primarily for elements that
acquire noble-gas configurations when they form
bonds.
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Atoms often gain, lose, or share electrons to
achieve noble gas electron configuration.
Why?
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They have eight valence electrons!
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Eight is the max amount of electrons that an
atom can possess in its outer shell.
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What does this mean? Once an atom has
eight valence e-, it is said to be completely
stable.
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* This rule has an exception (Transition
Metals!) but it does introduce many
concepts of bonding!
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All noble gases have eight valence
electrons!
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Illustrate the Lewis Symbol for Oxygen.
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Predict what would happen to the Lewis
symbol for oxygen if oxygen gained two
valance electrons.
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Define a chemical bond.
List the three types of chemical bonds.
Illustrate Lewis symbols for oxygen,
nitrogen, and sulfur.
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Chemical Party!
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By: Samantha Watt
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Chemical Bonds...
Lewis symbols...
Octet Rule...
Study Your Notes!
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List the three types of chemical bonds.
Chemical Bonds
Ionic & Covalent
Bonding
Bond Polarity &
Electronegativity
Lewis Structures
and Kekule’
Structures
E.Q.: How do I compare and contrast types of chemical
bonds?
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Metal + nonmetal
Electrons are transferred.
The transfer of e- from one atom to another.
Rxn of sodium chloride below...
The transfer of e- causes both ions to have
an octet.
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e- transfer to form oppositely charged ions.
Formation of Sodium Chloride!
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NaCl, KCl, and AlCl3...
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The principle reason that ionic compounds
are stable is the attraction between ions of
unlike charge.
Energy is released (exothermic) during the
rxn of Na and Cl.
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The sharing of e- between atoms.
Mostly between nonmetals.
Most substances that we come in daily
contact with!
Perfumes, water, plastic, gasoline, etc.
Sharing of e- causes both atoms to have an
octet.
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O2, CO2, and H2O...
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Glucose (C6H12O6)...
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Differentiate between an ionic bond and a
covalent bond.
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Chemical Bonding...
Ionic Bonding...
Energetics of Ionic Bonding
Covalent Bonding...
Study Your Notes!
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List the three types of bonds and
differentiate among them.
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Identify the following as covalent or ionic:
Chemical Bonds
Ionic & Covalent
Bonding
Bond Polarity &
Electronegativity
Lewis Structures
and Kekule’
Structures
E.Q.: Can I explain the effects of electronegativity on bond
polarity?
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Covalent bonds are the ___________of ebetween atoms.
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When identical atoms bonds, as Cl2 and H2,
e- pairs must be shared equally.
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Some covalent bonds, however, don’t always
have equal sharing of e- .
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Nonpolar covalent bond – Equal sharing of
e- pairs.
Polar covalent bond – Unequal sharing of epairs.
In nonpolar bonds,
electrons are shared
equally.
Polar bonds are also
depicted by partial positive
and partial negative
symbols …
Unequal sharing
in polar covalent
bonds.
Polar bonds are often
depicted using colors to show
electrostatic potential (blue =
positive, red = negative).
… or with a cross-based
arrow pointing to the more
electronegative element.
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ELECTRONEGATIVITY (EN) - Measure of the ability of
an atom to attract e- to itself.
EN is related to ionization energy.
The greater the EN of an atom in a molecule, the more
strongly the atom attracts e- in a covalent bond.
ELECTRONEGATIVITY generally
increases from left to right within a
period, and it generally increases from
the bottom to the top within a group.
It would be a good idea to
remember the four elements of
highest electronegativity: N, O, F,
Cl.
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The greater the difference in EN between two
atoms, the more polar their bond!
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Insert picture here
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Give two examples of polar covalent bonds
and nonpolar covalent bonds.
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Give two examples of ionic bonds.
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Bond Polarity...
Electronegativity...
Study Your Notes!
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Illustrate the Lewis symbols for all elements
on the third period of the periodic table.
Chemical Bonds
Ionic & Covalent
Bonding
Bond Polarity &
Electronegativity
Lewis Structures
and Kekule’
Structures
E.Q.: How can I represent the structure of atoms and nature of chemical
bonding through Lewis and Kekule’ structures?
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A combination of Lewis symbols...
Obey the octet rule...
Ex. CH4, NH3, H2O, and HF...
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Electrons not bonded – lone pairs.
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More Examples:
C2H6, H2O2, and C8H18...
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Lewis Structures...
Condensed Structures...
Study Your Notes!