Chemical Bonds

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Chemical Bonds
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Octet Rule atoms tend to gain, lose or share
electrons so as to have 8 electrons

• C would like to
• N would like to
• O would like to

Gain 4 electrons
Gain 3 electrons
Gain 2 electrons
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Chemical bonds an attempt to fill outer electron
shells. Bonds can occur between like elements and
unlike elements.

• There are three types we will look at
• Ionic bonds
• Covalent bonds
• Metallic bonds

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IONIC BONDbond formed between two ions
(opposite in charge) by the transfer of
electrons
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Ionic Bond

• Between metals and nonmetals with very different
  electronegativity (opposite charges)
• Bond formed by transfer of electrons
• Produce charged ions (all states of matter).
• Ionic compounds are conductors and have high
  melting points.
• Examples NaCl, CaCl2, K2O

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What are some characteristics of an ionic bond?

• Crystalline at room temperature
• Have higher melting points and boiling points
  compared to covalent compounds
• Conduct electrical current in molten or solution
  state but not in the solid state
• Polar bonds

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1). Ionic bond electron from Na is transferred
to Cl, this causes a charge imbalance in each
atom. The Na becomes (Na) and the Cl becomes
(Cl-), charged particles or ions.
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Commonly referred to as salt.
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COVALENT BONDbond formed by the sharing of
electrons
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Covalent Bond

• Between nonmetals of similar electronegativity
  (same charge).
• Formed by sharing electron pairs
• Compounds are stable non-ionizing particles
• They are not conductors at any state.
• Examples O2, CO2, C2H6, H2O, SiC

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What are some characteristics of a covalent bond?

• Covalent bonds have definite and predicable
  shapes.
• Very strong
• Low melting and boiling points

CH4, methane gas
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Covalent Bonds can have multiple bonds, so you
should be familiar with the following
Single Covalent Bond- chemical bond resulting
from sharing of an electron pair between two
atoms.
Double Covalent Bond- chemical bond resulting
from sharing of two electron pairs between two
atoms.
Triple Covalent Bond-chemical bond resulting from
sharing of three electron pairs between two
atoms.
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• Bonds in all the polyatomic ions are all covalent
  bonds

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when electrons are shared equally
NONPOLAR COVALENT BONDS
H2 or Cl2
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Share one or more pairs of outer-shell electrons.
Oxygen Atom
Oxygen Atom

Oxygen Molecule (O2)
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when electrons are shared but shared unequally
POLAR COVALENT BONDS
Ex. H2O
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- water is a polar molecule because oxygen is
more electronegative than hydrogen, and therefore
electrons are pulled closer to oxygen.
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METALLIC BONDbond found in metals holds metal
atoms together very strongly
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Metallic Bond

• Formed between atoms of metallic elements
• Electron cloud forms around atoms.
• Good conductors at all states, lustrous, very
  high melting points
• Examples Na, Fe, Al, Au, Co

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Metallic Bond, A Sea of Electrons
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Metals Form Alloys

• Metals do not combine chemically with metals.
• They form alloys, which are a solution of a metal
  within a metal.
• Examples are steel, brass, bronze and pewter.