chemical bond types

Chemical Bond Types Chemical Bond Types

Ionic Bonds Ionic Bonds

An ionic bond is formed

An ionic bond is formed by the attraction of oppositely chargedby the attraction of oppositely charged atoms or groups of atoms. When an atom (or group

atoms or groups of atoms. When an atom (or group of atoms)of atoms) gains or loses one or more electrons, it forms an

gains or loses one or more electrons, it forms an ionion. Ions have. Ions have either a net

either a net positive or net negative charge. Positively chargedpositive or net negative charge. Positively charged ions are attracted to the negatively charged 'cathode' in

ions are attracted to the negatively charged 'cathode' in anan electric field and are called

electric field and are called cationscations.. AnionsAnions are negatively are negatively charged ions named as a result of their

charged ions named as a result of their attractattraction to the positiveion to the positive 'anode' in an electric field.

'anode' in an electric field.

Every ionic chemical bond is made up of

Every ionic chemical bond is made up of at least one cation andat least one cation and one anion.

one anion. Ionic bonding

Ionic bonding is typically described to students as being the is typically described to students as being the outcome of the

outcome of the transfer of electron(s) beteen to dissimilartransfer of electron(s) beteen to dissimilar atoms. !he "eis structure belo

atoms. !he "eis structure belo illustrates this concept.illustrates this concept.

#or binary atomic systems, ionic bonding typically occurs beteen #or binary atomic systems, ionic bonding typically occurs beteen one metallic atom and one nonmetallic atom. !he

electronegativity difference beteen the

electronegativity difference beteen the highly electronegativehighly electronegative nonmetal atom and the metal atom indicates the potential for nonmetal atom and the metal atom indicates the potential for electron transfer.

electron transfer.

$odium chloride (%a&l) is the

$odium chloride (%a&l) is the classic eampleclassic eample of ionic bonding. of ionic bonding. Ionic bonding is not isolated to simple binary systems, hoever. Ionic bonding is not isolated to simple binary systems, hoever. An ionic bond can occur at the

An ionic bond can occur at the center of a large covalently bondedcenter of a large covalently bonded organic molecule such as an enyme. In this case,

organic molecule such as an enyme. In this case, a metal atom,a metal atom, lie iron, is both covalently bonded to large carbon groups and lie iron, is both covalently bonded to large carbon groups and ionically bonded to other simpler inorganic compounds (lie ionically bonded to other simpler inorganic compounds (lie oygen). *rganic functional groups, lie the carboylic acid

oygen). *rganic functional groups, lie the carboylic acid groupgroup depicted belo, contain covalent bonding in the carboyl portion depicted belo, contain covalent bonding in the carboyl portion of the group (+&**) hich itself serves as the anion to

of the group (+&**) hich itself serves as the anion to the acidicthe acidic hydrogen ion (cation).

hydrogen ion (cation).

Covalent Covalent

A covalent chemical bond results from the

A covalent chemical bond results from the sharing of electronssharing of electrons beteen to atoms ith

beteen to atoms ith similar electronegativities A singlesimilar electronegativities A single covalent bond represent the sharing of to

covalent bond represent the sharing of to valence electronsvalence electrons (usually from to different atoms). !he "eis structure belo (usually from to different atoms). !he "eis structure belo represents the

represents the covalent bondcovalent bond beteen to hydrogen atoms in a beteen to hydrogen atoms in a +

+ molecule. molecule.

D

Doot t SSttrruuccttuurree LLiinne e SSttrruuccttuurree

-ultiple covalent bonds are common for certain

-ultiple covalent bonds are common for certain atoms dependingatoms depending upon their valence configuration. #or eample, a double

upon their valence configuration. #or eample, a double covalentcovalent bond, hich occurs in ethylene (&

bond, hich occurs in ethylene (&++), results from the sharing of ), results from the sharing of  to sets of

to sets of valence electrons. Atomic nitrogen (%valence electrons. Atomic nitrogen (%) is an eample) is an eample of a triple covalent bond.

of a triple covalent bond. Double Covalent Bond  Double Covalent Bond 

Triple Covalent Bond  Triple Covalent Bond 

!he

!he polaritypolarity of a  of a covalent bond is defined by any difference incovalent bond is defined by any difference in electronegativity the to atoms

electronegativity the to atoms participating.participating. BondBond polarity

polarity describes the distribution of electron density around to describes the distribution of electron density around to bonded atoms. #or to bonded atoms ith similar

bonded atoms. #or to bonded atoms ith similar electronegativities

electronegativities, the electron density of the bond , the electron density of the bond is e/uallyis e/ually distributed beteen the to atom is !his is a

distributed beteen the to atom is !his is anonpolar covalentnonpolar covalent bond

bond. !he electron density of a covalent bond is shifted toards. !he electron density of a covalent bond is shifted toards the atom ith the

the atom ith the largest electronegativitylargest electronegativity. !his results in a . !his results in a netnet negative charge ithin the bond favoring the more

negative charge ithin the bond favoring the more

electronegative atom and a net positive charge for the least electronegative atom and a net positive charge for the least electronegative atom. !his is a

electronegative atom. !his is a polar covalent bond.polar covalent bond.

Coordinate Covalent Coordinate Covalent A

A coordinate covalent bondcoordinate covalent bond (also called a dative bond) is formed (also called a dative bond) is formed hen one atom donates both of the

hen one atom donates both of the electrons to form a singleelectrons to form a single covalent bond. !hese electrons originate from the donor atom as covalent bond. !hese electrons originate from the donor atom as an unshared pair.

an unshared pair.

0oth the ammonium ion and hydronium ion contain one 0oth the ammonium ion and hydronium ion contain one coordinate covale

coordinate covalent bond each. A nt bond each. A lone pair on the oygen atom inlone pair on the oygen atom in ater contributes to electrons to form

ater contributes to electrons to form a coordinate covalenta coordinate covalent bond ith a hydrogen ion to form the hydronium ion. $imilarly, a bond ith a hydrogen ion to form the hydronium ion. $imilarly, a lone pair on nitrogen contributes  electrons to form

lone pair on nitrogen contributes  electrons to form thethe ammonium ion. All of the bonds in these ions are

ammonium ion. All of the bonds in these ions are indistinguishable once

Ammonium (NH

Ammonium (NH44++)) HydroniumHydronium (H

(H33OO++))

Network Covalent Network Covalent

$ome elements form

$ome elements form very large molecules by forming very large molecules by forming covalentcovalent bonds. When these molecules repeat

bonds. When these molecules repeat the same structure over andthe same structure over and over in the entire piece of

over in the entire piece of material, the bonding of the substancematerial, the bonding of the substance is called netor covalent. 1iamond is an eample of carbon

is called netor covalent. 1iamond is an eample of carbon bonded to itself. Each carbon forms 

bonded to itself. Each carbon forms  covalent bonds to  othercovalent bonds to  other carbon atoms forming one large molecule the sie of

carbon atoms forming one large molecule the sie of each crystaleach crystal of diamond.

of diamond.

$ilicates, 2$i*

$ilicates, 2$i*33 also form  also form these netor covalent bonds.these netor covalent bonds. $ilicates are found in

$ilicates are found in sand, /uart, and many minerals.sand, /uart, and many minerals.

Metallic Metallic

!he valence electrons of pure

!he valence electrons of pure metals are not strongly metals are not strongly associatedassociated ith particular atoms. !his is a function of their lo

ith particular atoms. !his is a function of their lo ioniationioniation energy. Electrons in metals are said to be

energy. Electrons in metals are said to be delocalizeddelocalized (not found (not found in one specific region, such as beteen to

in one specific region, such as beteen to particular atoms).particular atoms). $ince they are not confined to a

$ince they are not confined to a specific area, electrons act lie aspecific area, electrons act lie a floing 4sea5,

floing 4sea5, moving about the positively charged cores of moving about the positively charged cores of thethe metal atoms.

metal atoms.

•

• 1elocaliation can be used to eplain conductivity,1elocaliation can be used to eplain conductivity,

malleability, and ductility. malleability, and ductility.

•

• 0ecause no one atom in a metal 0ecause no one atom in a metal sample has a strong holdsample has a strong hold

on its electrons and shares them ith its neighbors, e say on its electrons and shares them ith its neighbors, e say that they are bonded.

that they are bonded.

•

• In general, the greater the number of electrons per atomIn general, the greater the number of electrons per atom

that participate in metallic bonding, the

that participate in metallic bonding, the stronger the metallicstronger the metallic bond.