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