AIM: HOW TO FORM COVALENT BONDS DO NOW: EXPLAIN THE DIFFERENCE BETWEEN IONIC BONDING AND COVALENT BONDS. INCLUDE HOW THE PROPERTIES DIFFER IN SALTS AND MOLECULES, AND WHICH ELEMENTS ARE INVOLVED IN EACH TYPE OF BONDING.
OCTET RULE IN COVALENT BONDING In covalent bonding Atoms usually acquire a total of eight electrons, or an octet, by sharing electrons.
SINGLE COVALENT BOND A Single Covalent Bond consists of two atoms held together by sharing 1 pair of electrons (2 e - )
ELECTRON DOT STRUCTURE
SHARED VERSUS UNSHARED ELECTRONS A Shared Pair is a pair of valence electrons that is shared between atoms An Unshared Pair is a pair of valence electrons that is not shared between atoms
Chlorine forms a covalent bond with itself Cl 2
Cl Cl How will two chlorine atoms react?
Cl Cl Each chlorine atom wants to gain one electron to achieve an octet
Cl Cl Neither atom will give up an electron chlorine is highly electronegative. What s the solution what can they do to achieve an octet?
Cl Cl
Cl Cl
Cl Cl
Cl Cl
Cl Cl octet
Cl Cl octet circle the electrons for each atom that completes their octets
Cl Cl The octet is achieved by each atom sharing the electron pair in the middle circle the electrons for each atom that completes their octets
Cl Cl The octet is achieved by each atom sharing the electron pair in the middle circle the electrons for each atom that completes their octets
Cl Cl This is the bonding pair circle the electrons for each atom that completes their octets
Cl Cl It is a single bonding pair circle the electrons for each atom that completes their octets
Cl Cl It is called a SINGLE BOND circle the electrons for each atom that completes their octets
Cl Cl Single bonds are abbreviated with a dash circle the electrons for each atom that completes their octets
Cl Cl This is the chlorine molecule, Cl 2 circle the electrons for each atom that completes their octets
COVALENT BONDING IN H 2 Two hydrogen atoms, each with 1 electron, H.. H can share those electrons in a covalent bond. H: H Sharing the electron pair gives each hydrogen an electron configuration analogous to helium.
COVALENT BONDING IN F 2 Two fluorine atoms, each with 7 valence electrons,.... F.... :.. F: can share those electrons in a covalent bond..... :.. F:.. F: Sharing the electron pair gives each fluorine an electron configuration analogous to neon.
THE OCTET RULE In forming compounds, atoms gain, lose, or share electrons to give a stable electron configuration characterized by 8 valence electrons..... :.. F:.. F: The octet rule is the most useful in cases involving covalent bonds to C, N, O, and F.
Example Combine carbon (4 valence electrons) and four fluorines (7 valence electrons each).. C.. :.... F. to write a Lewis structure for CF 4..... :.. F:.. :.. F: C.. :.. F: :.. F: The octet rule is satisfied for carbon and each fluorine.
Example It is common practice to represent a covalent bond by a line. We can rewrite.... :.. F:.. :.. F: C.. :.. F: :.. F: as.. : F:.... :.. F C.. F: :.. F:
PRACTICE LEWIS DOT STRUCTURES Chemical Formula # of Valence Electrons # of Shared Electrons # of Remaining Electrons Lewis Dot Structure Octet Check All Atoms=8 Hydrogen=2 F 2 H 2 O NH 3 CH 4
DOUBLE COVALENT BONDS Sometimes atoms attain noble gas configuration by sharing 2 or 3 pairs of electrons A Double Covalent Bond is a bond that involves 2 shared pairs of electrons (4 e - )
O2 Oxygen is also one of the diatomic molecules
O O How will two oxygen atoms bond?
O O Each atom has two unpaired electrons
O O
O O
O O
O O
O O
O O
O O Oxygen atoms are highly electronegative. So both atoms want to gain two electrons.
O O Oxygen atoms are highly electronegative. So both atoms want to gain two electrons.
O O
O O
O O
O O
O O Both electron pairs are shared.
O O 6 valence electrons plus 2 shared electrons = full octet
O O 6 valence electrons plus 2 shared electrons = full octet
O O two bonding pairs, making a double bond
O O O =O For convenience, the double bond can be shown as two dashes.
O =O This is the oxygen molecule, O2 this is so cool!!
TRIPLE COVALENT BOND A Triple Covalent Bond is a bond that involves 3 shared pairs of electrons (6 e - )
COVALENT BONDS
PRACTICE LEWIS DOT STRUCTURE Chemical Formula # of Valence Electrons # of Shared Electrons # of Remaining Electrons Lewis Dot Structure Octet Check All Atoms=8 Hydrogen=2 O 2 CO 2 N 2 HCN