Download Bonding in Atoms

Bonding in Atoms
What keeps us together
Valence Electrons
• Electrons located in the
outer shell
• Readily available for
bonding
• Always s or p sublevel
• Follows the Octet Rule
• Modeled by the Lewis
Dot Diagram
The Octet Rule
• States that an atom will lose or gain electrons in
order to fill the outer sublevels (s and p)
• Modeled by the Lewis Dot Diagram
• Gain of electrons = anion
• Loss of electrons = cations
Chemical Formulas and Units
• A chemical formula shows the kinds of atoms in
the molecule as well as the amount of atoms in
the molecule
• A formula unit is expressed in the smallest whole
number ratio for the molecule
• Examples:
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NaCl
TiO2
VCl5
Ca3(PO4)2
Ionic Bonding
• Formed from an exchange in electrons forming
two charged ions
• Electrons are completely exchanged
• Strongest type of bond
Ionic Bond Characteristics
• Compounds of ionic bonding are often solid at
room temperature
• Compounds will have a high melting point with
ionic bonds
• Compounds will become conductive when
melted or dissolved
Binary Ionic Compounds
• A Bicycle has how many wheels?
• A biplane has how many wings?
• A binary compound has how many elements?
• A binary ionic compound has two elements
where electrons are exchanged
• NaCl Sodium Chloride
• MgBr2 Magnesium Bromide
• Ca3N2 Calcium Nitride
Polyatomic Ions
• What is polytheism?
• What is a polygon?
• How about polyatomic ions?
• Polyatomic ions are IONS that consist of
multiple atoms
• Polyatomic ions are used in ionic bonding
because there is still an exchange in
electrons
Covalent Bonding
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Electrons are shared!
Low melting point
Liquid or gas at room temperature
Volatile
Weaker bond
Can be polar
Covalent Bonding
• Bonds can occur as single, double, or triple
bonds
• Each bond represents a pair of electrons
• Best represented in diatomic molecules
(F, Cl, Br, I, H, N, O)
• Lewis Dot Diagram helps determine where a
double or triple bond can occur
Covalent Bonding
• VSEPR Theory
• Valance shell electron pair repulsion theory
• Predicts the shape of a molecule (covalent
compound)
• Lone pair on the central atom push the ligands
together altering the bond angles between the
ligands
• Practice: CHI3, CO2, NH3, CH2O, SO3, HCN
VSEPR Shapes
Covalent Naming
• Name is
determined by the
number of atoms
in the molecule
• MUST be covalent
• CO2, SO3, O3, C3O6
Van der Waals Forces
• London Dispersion Forces
• Weakest
• Includes compounds with non-polar forces
• Increases as the number of electrons increases
• Dipole-Dipole Forces
• Next strongest
• Compounds that are polar
• Increases as mass increases
• Hydrogen bonding
• Extremely strong dipole forces
• H-F, H-N, H-O
Transition Metals
• Transition metals have empty orbitals available
for electron movement
• This movement results in multiple cations
• Cations can be predicted using electron
notation
• Let’s look at copper!
Transition Metal Cations
Metallic Bonding
• Attraction of free floating electrons in the cloud
• Flow of electrons allows for great conductivity
• Also allows for malleability
• Often arranged in a crystalline structure
• Alloys is a mixture that includes at least one
metal and enhances the properties of the metal