2.9 Covalent Bonding

2.9 Covalent Bonding

Sharing electrons to achieve stability.

It's how nonmetals bond with other nonmetal atoms.

Molecules are formed. (discrete, electrically-neutral particles of matter... they be small y'all)

Covalent Bonds involve nonmetals only.

...Who are the Nonmetals again?

Elements to the right of the staircase line AND Hydrogen , H

Prior Knowledge

• Electron configuration

• Valence electrons

• location of nonmetals on P.T.

• Octet Rule

• rapid fire set of questions up next. Be ready to flip to periodic table

Multiple Choice

What is the electron configuration of chlorine? (symbol, Cl , Group 17)

• 2-7

• 2-8-7

• 2-8-8

Multiple Choice

How many valence electrons does an atom of chlorine have?

• 2

• 7

• 8

Multiple Choice

If forming an ion, What will an atom of chlorine do to achieve 8 valence electrons?

• gain 1

• lose 7

If a metal atom is around, 1 electron will transfer to the chlorine atom... making it a 1- chloride ion (that is ionic bonding)

But what if there are no metal atoms around?

What if there are only other nonmetal atoms nearby?

Covalent Bonding

Sharing valence electrons , not transferring them.

Key information for Covalent Bonding

• " Co " = share ; "valent" = valence shell (valence electrons)

• A Covalent Bond is: A chemical bond formed when two atoms share valence electrons. (Typically, two nonmetal atoms)

• Sharing takes place until each atom has access to 8 valence electrons (Octet Rule ; exceptions of Hydrogen... needs only 2)

• Example: In a molecule of Cl₂ , each chlorine atom donates an electron into a covalent bond in the molecule , which results in each Cl atom having access to 8 total valence electrons (each started with 7).

Hydrogen is a nonmetal and is an exception to the Octet Rule

It only needs to form one covalent bond and have access to 2 valence electrons.

Can bond to itself, making H₂

Or to others, such as carbon (CH₄)

Electrons are shared to form one, two, or three bonding pairs

• Single Covalent Bond: One shared pair (Ex: in Cl₂)

• Double Covalent Bond: Two shared pairs (Ex: in O₂)

• Triple Covalent Bond: Three shared pairs (Ex: in N₂)

• Bonding pairs of electrons represented as dots or as dashes in Lewis Dot Diagrams (examples on next slide)

New Term: Valency

The number of covalent bonds that an atom needs to reach stability

(Typically, to reach access to 8 valence electrons.)

How-to:

Simply count the number of unpaired electrons in the atom's Lewis Dot Diagram

Multiple Choice

How many unpaired electrons in the Lewis Dot Diagram of an atom of fluorine? (this will determine how many covalent bonds it needs to form... its valency)

(click the image to enlarge)

• 1

• 2

• 3

Multiple Choice

How many covalent bonds does an atom of oxygen need to form to be stable?

(click image to enlarge)

• 1

• 2

• 3

Lewis Dot Diagrams of nonmetal atoms are the key to determining how they bond with each other

But how to draw them?

(Mr. M demonstrating after the Quizizz Lesson concludes)

Recap

• nonmetals can form covalent bonds with other nonmetal atoms

• covalent bonds involve the sharing of valence electrons

• Typically, each atom contributes one valence electron into each covalent bond (thus, bonding pairs are formed)

• The number of unpaired valence electrons an atom has determines how many covalent bonds it needs (a.k.a. its valency)

Multiple Select

Which of the following elements could be involved in covalent bonds?

Select all that apply.

• H, hydrogen

• Na, sodium

• S, sulfur

• Fe, iron

Multiple Choice

Covalent bonding involves the ...

• transferring of electrons from one atom to another

• the sharing of electrons between atoms

• the attraction between metal cations and a sea of mobile electrons

For Definitions and Examples of Covalent Bonding, Lewis Dot Diagrams and Structures... go to Quizlet

"2.9 Covalent Bonding"