Lewis-Structures-Unraveling-Molecular-Compounds.pdf

lewis structure unraveling molecules

1. Lewis Structures :
Unraveling Molecular
Compounds
Lewis structures are a powerful tool for understanding the bonding and
structure of molecules . They help us visualize how atoms share electrons to
form covalent bonds , providing valuable insights into the properties of
chemical compounds .
by Ariane Jane Cabales Soner Ariane

2. Introduction to Lewis
Structures
1
Representing
Molecules
Lewis structures use symbols
and lines to represent the
arrangement of atoms and
electrons in a molecule .
2
Valence Electrons
They focus on the valence
electrons , which are the
electrons in the outermost
shell of an atom .
3
Bonding and Non - bonding Electrons
They depict both bonding and non - bonding ( lone pairs ) electrons ,
providing a complete picture of the electron distribution .

3. Covalent Bonds and Shared Electron Pairs
Sharing Electrons
Covalent bonds form when two atoms
share electrons to achieve a stable
electron configuration .
Electron Pairs
Each shared pair of electrons
constitutes a single covalent bond ,
represented by a line in the Lewis
structure .
Bonding Capacity
The number of covalent bonds an atom
can form depends on its valence
electrons , following the octet rule .

4. Octet Rule and Exceptions
Octet Rule
Atoms tend to gain , lose , or
share electrons to achieve a
stable configuration with eight
valence electrons .
Exceptions
Some elements , like hydrogen
and lithium , are stable with only
two valence electrons . Other
elements can have more than
eight valence electrons in their
Lewis structures .

5. Drawing Lewis Structures Step - by - Step
1
Step 1: Determine the Central Atom
The least electronegative atom typically forms the
central atom .
2
Step 2: Count Valence Electrons
Sum up the valence electrons of all atoms in the
molecule .
3
Step 3: Connect Atoms with Single Bonds
Place single bonds between the central atom and
surrounding atoms .
4
Step 4: Complete Octet
Add lone pairs to surrounding atoms until they
achieve an octet .
5
Step 5: Place Remaining Electrons on the
Central Atom
If necessary , place remaining electrons as lone pairs
on the central atom .

6. Formal Charge and
Electronegativity
Formal Charge Definition
Electronegativity An atom ' s ability to attract
electrons in a bond
Polar Covalent Bond A bond where electrons are
unequally shared

7. Resonance Structures
1
Delocalized Electrons
Resonance occurs when multiple Lewis structures can be
drawn for a molecule , with electrons delocalized over multiple
bonds .
2
Stable Hybrid
The actual structure of the molecule is a hybrid of all possible
resonance structures , resulting in a more stable molecule .

8. Predicting Molecular
Geometry with VSEPR Theory
Shape
VSEPR theory predicts the shape of a molecule based on the repulsion
between electron pairs .
Bond Angles
Electron repulsion influences bond angles , leading to specific molecular
geometries .
Polarity
Molecular geometry contributes to the polarity of a molecule , influencing its
interactions with other molecules .

9. Polarity and Intermolecular
Forces
1
Dipole - Dipole
Interactions
Polar molecules attract each
other due to their permanent
dipoles .
2
London Dispersion
Forces
All molecules exhibit
temporary induced dipoles ,
leading to weak London
dispersion forces .
3
Hydrogen Bonding
A strong type of dipole - dipole interaction involving hydrogen bonded
to highly electronegative atoms like oxygen , nitrogen , or fluorine .

10. Applications of Lewis Structures
Materials Science
Lewis structures are fundamental in understanding the structure
and properties of polymers and other materials .
Biochemistry
They help visualize the structure and bonding patterns of
complex biomolecules like proteins and DNA .