compounds and bonding putting 2 and 2 together. covalent bonds

Compounds and BondingCompounds and Bonding

Putting 2 and 2 TogetherPutting 2 and 2 Together

CovalentBonds

Sowhatarecovalentbonds?

Covalent Bonding: Sharing electrons

Cl2

Chlorineforms

acovalent

bondwith

itself

ClClHowwilltwochlorineatomsreact?

ClClEach chlorine atom wants to gain one electron to achieve an octet

ClClNeither atom will give up an electron –chlorine is highly electronegative.

What’s the solution – what can theydo to achieve an octet?

ClCl

Cl Cl

Cl Cl

ClCl

ClCloctet

ClCl

circle the electrons foreach atom that completestheir octets

octet

ClCl

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The octet is achieved byeach atom sharing theelectron pair in the middle

ClCl

circle the electrons foreach atom that completestheir octets

The octet is achieved byeach atom sharing theelectron pair in the middle

ClCl

circle the electrons foreach atom that completestheir octets

This is the bonding pair

ClCl

circle the electrons foreach atom that completestheir octets

It is a single bonding pair

ClCl

circle the electrons foreach atom that completestheir octets

It is called a SINGLE BOND

Cl Cl

circle the electrons foreach atom that completestheir octets

Single bonds are abbreviatedwith a dash

Cl Cl

circle the electrons foreach atom that completestheir octets

This is the chlorine molecule,

Cl2

O2

Oxygen is also one of the diatomic molecules

How will two oxygen atoms bond?

OO

OOEach atom has two unpaired electrons

OO

OO

OO

OO

OO

OO

Oxygen atoms are highly electronegative.

So both atoms want to gain two electrons.

OO

Oxygen atoms are highly electronegative.

So both atoms want to gain two electrons.

OO

OO

OO

OO

OO

OOBoth electron pairs are shared.

6 valence electronsplus 2 shared electrons

= full octet

OO

6 valence electronsplus 2 shared electrons

= full octet

OO

two bonding pairs,

OOmaking a double bond

OO =For convenience, the double bond

can be shown as two dashes.

OO

OO =This is the oxygen molecule,

O2this is so cool!!

• When two pairs of electrons are shared it is called a double bond.

H H \ / C C / \ H H

• When three pairs of electrons are shared it is called a triple bond.

H-C C-H

• When two pairs of electrons are shared it is called a double bond.

H H \ / C C / \ H H

• When three pairs of electrons are shared it is called a triple bond.

H-C C-H

Ionic Bonding

• Ionic Bonds

– Ionic bonding occurs when one atom transfers an electron to another atom

•This occurs when a metal reacts with a nonmetal

• Ionic Bonds

– Ionic bonding occurs when one atom transfers an electron to another atom

•This occurs when a metal reacts with a nonmetal

Na+1 + Cl-1 ® NaCl (table salt)

• Two rules for keeping track of electrons in ionic bonding reactions.

–Ions are formed when atoms gain or lose electrons to achieve a noble gas configuration (octet rule)

–The number of electrons that are lost must equal the number of electrons that are gained.

• Two rules for keeping track of electrons in ionic bonding reactions.

–Ions are formed when atoms gain or lose electrons to achieve a noble gas configuration (octet rule)

–The number of electrons that are lost must equal the number of electrons that are gained.

– Ionic Compounds

– Compounds that are held together by ionic bonds are called ionic compounds.• The elements in Group IA and IIA tend to lose

electrons for form positive ions (Cations)

• The elements in Group VIA and VIIA tend to gain electrons to form negative ions. (Anions)

– Ionic Compounds

– Compounds that are held together by ionic bonds are called ionic compounds.• The elements in Group IA and IIA tend to lose

electrons for form positive ions (Cations)

• The elements in Group VIA and VIIA tend to gain electrons to form negative ions. (Anions)

N O Cl

N3-

nitride ionO2-

oxide ionCl-

chloride ion

Example of anions

Some examples of Cations:

Na Sr Ba

Na+

sodium ionSr2+

strontium ionBa2+

barium ion

IONICBONDING

In an IONIC bond,electrons are lost or gained,resulting in the formation of IONSin ionic compounds.

FK

FK

FK

FK

FK

FK

FK

FK+ _

FK+ _

The compound potassium fluorideconsists of potassium (K+) ions

and fluoride (F-) ions

FK+ _

The ionic bond is the attractionbetween the positive K+ ion

and the negative F- ion