Two types of chemical bonds are Ionic Bonds and Covalent Bonds
Chemical Bonding: Covalent Bonding
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Chemical Bonds Two types of chemical bonds are Ionic Bonds and
Covalent Bonds
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Covalent Bonding The chemical bond formed when two atoms share
electrons Covalent means share Way to remember: CO together like a
couple or companion Way to remember: VALENT valence electrons What
is the difference between a covalent bond and an ionic bond?
Electron sharing occurs when atoms such as Hydrogen bond to other
nonmetals or with the same element
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Covalent Bonding By sharing electrons, each atom has a stable
set of eight The force that holds atoms together in a covalent bond
is the attraction of each atoms nucleus for the shared pair
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Covalent Bonding: Molecules What is a molecule? Neutral group
of atoms joined by covalent bonds Ex. 2 Fluorine atoms form a
Fluorine molecule
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Covalent Bonding Except for Hydrogen, the number of covalent
bonds that nonmetal atoms can form equals the number of electrons
needed to make a total of eight Ex. Nitrogen has 5 valence
electrons and Hydrogen has 1 valence electron
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Covalent Bonding Double bonds are when two atoms share two
pairs of electrons Ex. CO2 Triple bonds are when atoms share three
pairs of electrons Ex. Nitrogen What is the difference between a
double bond and a triple bond? A double bond shares 4 electrons and
a triple bond shares 6 electrons
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Covalent Bonding: Molecular compounds What is a molecular
compound? A molecular compound is a compound that is composed of
molecules The molecules of a molecular compound contain atoms that
are covalently bonded What are the properties of molecular
compounds? Low melting points and boiling points Do not conduct
electricity when dissolved in water
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Covalent Bonding: Molecular Compounds What is unequal sharing
of electrons? Atoms of some elements pull more strongly on shared
electrons than do atoms of other elements As a result, the
electrons are pulled more towards one atom, causing the bonded
atoms to have slight electrical charges which are not as strong as
the charges on ions
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Covalent Bonding Polar Bonding A covalent bond in which
electrons are shared unequally The unequal sharing of electrons is
enough to make the stronger pull slightly negative and the weaker
pull slightly positive Ex. H2O Nonpolar Bonding A covalent bond in
which electrons are shared equally If two atoms pull equally on the
electrons, neither atom becomes charged Ex. F2
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Covalent Bonding: Bonding in Metals What is an alloy? Mixture
made of two or more elements that has the properties of a metal In
every alloy, at least one of the elements is a metal Alloys are
generally stronger and less likely to react with water than are the
pure metals from which they are made
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Covalent Bonding: Metallic Bonding What is a metallic bond? An
attraction between a positive metal ion and the electrons surround
it Metals are in group 1, 2, and 3 so they lose electrons easily
because their valence electrons are not strongly held Each metal
ion is held by a metallic bond The more valence electrons an atom
can add, the stronger the metallic bond will be
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ADD THE FOLLOWING NOTES TO YOUR PREVIOUS COVALENT BOND NOTES.
YOU WILL WRITE DOWN THE FOLLOWING NOTES. THEY ARE NOT
FILL-IN-THE-BLANK. YOU MAY HAVE TO USE A NEW SHEET OF PAPER.
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Covalent Bonding Attraction between neutral atoms Formed by
sharing e - between two nonmetals Cl
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Covalent Bonding Covalent bonds result in discrete molecules Cl
2 H2OH2O NH 3
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Nonpolar Covalent Bonds e - are shared equally usually
identical atoms Ex: Carbon Dioxide Covalent Bonding (-) (+) (-)
Opposite pulling cancels out CO 2
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Polar Covalent Bonds e - are shared unequally between 2
different atoms results in partial opposite charges Ex: Water
Covalent Bonding H2OH2O (-) (+)
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Covalent Bonding Sharing Electrons:
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H2OH2O 2 hydrogen atoms 1 oxygen atom Shows: 1) elements in the
compound 2) ratio of their atoms Covalent Bonding
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Nonpolar Polar Ionic Covalent Bonding
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Ionic and Covalent Bonds Comparison Chart IONIC COVALENT
Electrons Melting Point Soluble in Water Conduct Electricity Other
Properties transferred from metal to nonmetal high yes (solution or
liquid) yes crystal lattice of ions, crystalline solids shared
between nonmetals low no usually not molecules, odorous liquids
& gases
