Chemical Bonding
Chemical Bonding
Chemical Bonding
• Lewis symbols use dots to visually represent the valence electrons of an atom
KEY IDEAS IN THE LEWIS ELECTRON DOT
STRUCTURE
• Electrons exist outside of an atom ‘s nucleus and are found in principal energy levels that contain
only up to a specific number of electrons.
• The outermost principal energy level that contains electrons is called the valence level and
contains valence electrons.
• Lewis symbols are diagrams that show the number of valence electrons of a particular element
with dots that represent lone pairs.
• Lewis symbols do not visualize the electrons in the inner principal energy levels.
IMPORTANT TERMS
• PRINCIPAL ENERGY LEVELS: The different levels where electrons can be found and that occur at
specific distances from the atom’s nucleus. Each level is associated with a particular energy value that
electrons within it have.
• VALENCE LEVEL: The outermost principal energy level, which is the level furthest away from the
nucleus that still contains electrons.
• VALENCE ELECTRONS: The electrons of atoms that participate in the formation of chemical
bonds.
• LEWIS SYMBOLS: Symbols of the elements with their number of valence electrons represented as
dots
CHEMICAL BONDING
• Because they’re polarized, two adjacent H2O (water) molecules can form a linkage known as
a hydrogen bond, where the (electronegative) hydrogen atom of one H 2O molecule is
electrostatically attracted to the (electropositive) oxygen atom of an adjacent water molecule.
• Consequently, molecules of water join together transiently in a hydrogen-bonded lattice.
Hydrogen bonds have only about 1/20 the strength of a covalent bond, yet even this force is
sufficient to affect the structure of water, producing many of its unique properties, such as high
surface tension, specific heat, and heat of vaporization. Hydrogen bonds are important in many
life processes, such as in replication and defining the shape of DNA molecules.