Sharing Nicely: Covalent Bonding€¦ · 21/01/2019 · IONIC VS. COVALENT BONDS Ionic Covalent...
Transcript of Sharing Nicely: Covalent Bonding€¦ · 21/01/2019 · IONIC VS. COVALENT BONDS Ionic Covalent...
Sharing Nicely: Covalent Bonding
Chemistry 1
RECAP● Ionic Bonding:
○ Involves the donation or transfers of electrons ○ Examples: Sodium Chloride , Calcium Carbonate
RECAP: LEWIS STRUCTURES
Covalent Bonding Video: https://www.youtube.com/watch?v=LkAykOv1foc
IONIC VS. COVALENT BONDS Ionic Covalent
● Involve transfer of electrons ● Between a metal and a
nonmetal ● High melting points/boiling
points ● Form crystal lattices ● Soluble in water
● Also called “molecular” ● Involve the sharing of
electrons ● Between two non-metals
and diatomic molecules ● Low melting points/ boiling
points ● Insoluble in water ● Can involve single, double
and triple bonds
Intro to Covalent Bonds
● Covalent Bonds involve the sharing of electrons.
○ They are found in other ingredients like sugar, water and even hold DNA together!
● Elements desire to be stable, they want to completely fill their valence shells with octets
Types of Covalent Bonds
1. Diatomic Molecules: two identical elements that share electrons
2. Two nonmetals that share electrons
Types of Covalent Bonds: Diatomic Molecules
1. Diatomic Molecules: two of the same elements that are bonded to each other. YOU NEED TO KNOW THESE:
Types of Covalent Bonds: Diatomic Molecules
1. Diatomic Molecules:a. Example: F2 Diatomic Molecule
Types of Covalent Bonds: Two Nonmetals
2. Elements that are generally close on the periodic Table. Non-metals tend to form covalent bonds with each other.
IONIC OR COVALENT?
MgO
I2
NaCl
C02
Intro to Covalent Bonds ● Covalent bonds can be represented in different ways
Consider the covalent bond between 2 Hydrogen atoms:
Electron-dot Formula
Lewis Structural Formula
Writing Electron Dot Formulas + Lewis Structural Formulas
1. Identify if the Compound is Ionic or Covalent
2. Identify the number of valence electrons for each element.a. Hydrogen has 1 valence
electronb. Oxygen has 6 valence
electrons 3. Draw the Lewis Dot Structures
for each
Hydrogen & Oxygen are nonmetals, so it is a covalent bond
Writing Electron Dot Formulas + Lewis Structural Formulas
4. Central atoms are the ones that are in the center of the bond. Carbon, Silicon, Nitrogen, Phosphorus, Oxygen and Sulfur are good central atoms.
5. Determine how many electrons each atom needs to obtain a full octet.
Hydrogen needs 1; Oxygen needs 2 more
Writing Electron Dot Formulas + Lewis Structural Formulas
4. Write the correct Electron Dot Formula
Writing Electron Dot Formulas + Lewis Structural Formulas
5. Lewis Structural Formulas indicates the number of bonds that each compound contains.
a) Determine bonding and non-bonding pairs
Example: PH3
Example: H2S
Example: HCL
Example: CCl4
Single, Double and Triple Covalent Bonds
Single Bonds: When only one pair of electrons is shared
Double Bonds: When 2 pairs of electrons (4 in total) are shared
Triple Bonds: When 3 pairs of electrons (6 in total) are shared.
Single, Double & Triple Bonds
Covalent Bonds involves a series of attractive and repulsive forces.
Covalent Bonds can different in strength and length.
Single, Double & Triple Bonds
The shorter the bond, the stronger it is:
Single bonds are the longest and the weakest bonds
Double bonds are in shorter and stronger than single bonds
Triple bonds are shortest and strongest.
Example: O2
Example: N2
RECAP: Intro to Covalent Bonds ● Covalent Bonds
involve the sharing of electrons between two non-metals, which can be two of the same element (diatomic molecules)
RECAP: Intro to Covalent Bonds ● Octet Rule: In
order to be stable, atoms share electrons in order to a full outermost shell. Atoms will try to obtain 8 valence electrons.
RECAP: How to Draw Covalent Bonds 1. Lewis
Structures 2. Electron Dot
Structures 3. Lewis
Structural Formula
** Central atoms: C, N, S , F, Si, O
1 2 3
Example: CO2
Example: HCN
Example: C2H4
Example: C2H2
Example: CF3Cl
Exceptions to the Octet Rule:
1. Incomplete Octets: Central atom does not have enough electrons to get to 8 valence electrons a. Example: BF3, NO2
Exceptions to the Octet Rule: 2. Expanded Octets: Central Atom can hold more than 8 valence electrons
Examples: PCl5, ClF3
Naming Binary Covalent/Molecular Compounds
1. The first element in the formula is always named first, using the entire element name
2. The second element in the formula is always named using its root and adding the suffix -ide
3. Prefixes are used to indicate the number of atoms of each element
Naming Binary Covalent/Molecular Compounds
1. The first element in the formula is always named first, using the entire element name
2. The second element in the formula is always named using its root and adding the suffix -ide
3. Prefixes before each root are used to indicate the number of atoms of each element.
SO2
Sulfur Dioxide
Naming Binary Covalent/Molecular Compounds
1. The first element in the formula is always named first, using the entire element name
2. The second element in the formula is always named using its root and adding the suffix -ide
3. Prefixes before each root are used to indicate the number of atoms of each element.
CO
Carbon Monoxide
Naming Binary Covalent/Molecular Compounds
1. The first element in the formula is always named first, using the entire element name
2. The second element in the formula is always named using its root and adding the suffix -ide
3. Prefixes before each root are used to indicate the number of atoms of each element.
S2Cl2
Disulfur dichloride
Examples: Naming
● KrF3● SiO2● N2S3● PCl5
Examples: Working Backwards
● Sulfur tetrachloride ● Xenon Trioxide ● Dinitrogen Trioxide ● Phosphorus Pentachloride