Covalent Bonding

What is covalent bonding?

bonding by sharing electrons

What types of elements can covalently bond?

Hydrogen and nonmetals

Steps in covalent bonding

1. sum all valence electrons

2. select the center atom (the singular one, without subscript)

3. bond outside elements with single sigma bonds

4. subtract the electrons used in the sigma bonds (each sigma bond has 2 electrons)

5. add electron pairs to outside elements to form octets (have 8 electrons)

6. subtract the electrons used to form the octets (usually 6 electrons per outside element)

7. add any remaining electrons to the center atom in pairs

8. check for octets (especially center atom), move electron pairs to form pi bonds if needed

What is a sigma bond?

2 shared electrons between atoms, σ

What is a pi bond?

an electron pair above and/or below a sigma bond

What is a single bond made up of?

one sigma (σ) bond

What is a double bond made up of?

one sigma (σ) bond and one pi (π) bond

What is a triple bond made up of?

one sigma (σ) bond with one pi (π) bond above it and one pi (π) bond below it

How many electrons does a single bond share?

2 electrons

How many electrons does a double bond share?

4 electrons

How many electrons does a triple bond share?

6 electrons

If given CF₄, what is the center atom and what are the outside elements?

C is the center atom and the 4 Fs are the outside elements

When the sum of sigma bonds and electron pairs around the center atom is 2, what is its hybridization?

sp

When the sum of sigma bonds and electron pairs around the center atom is 3, what is its hybridization?

sp²

When the sum of sigma bonds and electron pairs around the center atom is 4, what is its hybridization?

sp³

When the sum of sigma bonds and electron pairs around the center atom is 5, what is its hybridization?

dsp³

When the sum of sigma bonds and electron pairs around the center atom is 6, what is its hybridization?

d₂sp³

What is the molecular geometry and bond angle if the hybridization is sp?

linear, 180°

What are the possible molecular geometry and bond angles if the hybridization is sp²?

• planar triangle (no electron pairs), 120°

• bent (1 electron pair), less than 120°

What are the possible molecular geometry and bond angles if the hybridization is sp³?

• tetrahedron (0 electron pairs), 109.5°

• triangular pyramid (1 electron pair), less than 109.5°

• bent (2 electron pairs), less than 109.5°

What are the possible molecular geometry and bond angles if the hybridization is dsp³?

• triangular bipyramidal (0 electron pairs), 90° and 120°
• seesaw (1 electron pair), 90°, 180°, and less than 120°
• T-shape (2 electron pairs), 90° and 180°
• vertical linear (3 electron pairs), 180°

What are the possible molecular geometry and bond angles if the hybridization is d₂sp³?

• octahedron (0 electron pairs), 90°
• square pyramid (1 electron pair), 90°
• square planar (2 electron pairs), 90°

How do you find out if the covalent bond is non-polar or polar?

calculate the electronegativity difference (E.N.D.), keep it positive

How do you know if the covalent bond is non-polar?

the E.N.D. is 0, 0.1, or 0.2

How do you know if the covalent bond is polar?

the E.N.D. is 0.3 or greater

How do you find out if the molecule is non-polar or polar?

by judging its symmetry. if it's symmetrical = non-polar, if it's non-symmetrical = polar

A non-polar covalent bond always has what type of molecule?

a non-polar molecule

How do you find out the polarity of a molecule with a polar covalent bond?

have to check if the structure is symmetrical or not; if it's symmetrical = non-polar molecule, if it's not symmetrical = polar molecule

Molecular geometry structures that HAVE symmetry

• linear (sp)
• planar triangle (sp²)
• tetrahedron (sp³)
• trigonal bipyramidal (dsp³)
• linear (dsp³)
• octahedron (d₂sp³)
• square planar (d₂sp³)

Molecular geometry structures that DO NOT HAVE symmetry

• bent (sp²)
• triangular pyramid (sp³)
• bent (sp³)
• seesaw (dsp³)
• T-shape (dsp³)
• square pyramid (d₂sp³)