CHEMICAL BONDING

Theories of Chemical Bonding

Chemical Bonding

• Ionic

• Covalent

• Metallic

Chemical Bonding

• Ionic Bonding

Ionic Bonding

• Ionic Bonding (rip-off: nonmetals rip electrons off metals) An Ionic Chemical bond is the electrostatic attraction between two oppositely charged ions, positive metal cations and negative nonmetal anions.

• This attraction between ions makes an ionic chemical bond and forms a new pure substance with new and different properties, a new compound with zero net charge.

new compoundNa+

F−

NaFx x +

x

x

x

Na

x

x

x

x x

x x −

x

x

x

F

x

x

x

x x

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Ionic Bonding

Naming Ionic Compounds The ionic compound has oppositely charged ion pairs. (cations and anions) The ionic compound is named by placing the name of the cation first followed by the anion's name.

caton anion (compound)

sodium + chloride -> sodium chloride

Na+

Cl− NaCl

Ionic Bonding

Naming Ionic Compounds 1. First name partner ions

• The cation has the same name as the element.

• The anions name is derived from the name of the element by taking the first syllable and adding "ide'. (All binary compounds (two elements only) will therefore end in ide)

» sodium chloride• complex or polyatomic ions: Sometimes groups of atoms

behave as a single charged particle. These are called complex or polyatomic ions .In this case the compound resulting of the

ionic bond will have more than two elements. » sodium chlorate

NaCl

NaClO3

Ionic BondingWriting Formulas for Ionic Compounds

• The cat comes first: The metallic cation is always written first followed by the anion.

– EITHER Use the method outlined in the document at the left to obtain the ion charges

– OR Use the "Periodic Table Of Ions" to write the ion symbols ex. .

• The zero sum rule is the applied to give the formula of the ionic compound zero net charge. Applying the "Zero Sum Rule”: In an ionic compound the electrons lost by the cations must equal those gained by the anions.

– Choose a lest common denominator for the ion charges. Place multipliers after the foot of each ion to indicate the number of ions required for the ion charges to balance.

– Write the formula with the subscripts without the ion charges. (Remember that all formulas/ compounds have zero net charge.

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Mg2+

Cl−

MgCl2

Chemical Bonding

• Covalent Bonding

Covalent Bonding

– Covalent Bonding: A Covalent Chemical bond is the electrostatic attraction of two nuculi for a shared pair of electrons found between them. Nucleui (+) are oppositely charged form the electrons that are (-). This attraction between electrons and nucleui forms a new pure substance with new and different properties, a new molecular substance.

– E.g. Chlorine with it’s seven valance electrons completes its valance electrons by sharing one unpaired electron with another chlorine atom

x xx

xCl

xx x

x xx

Clx

xx x

x xx

xCl

x

xx x

x x

Clx

xx x

Covalent Bonding

• In covalent bonding (sharing electrons) Covalent bonds are the electrostatic charge of positive nonmetal nucleui holding on to the same pair of negative electrons shared between them. Sharing of valance electrons allows them to obtain a nobel gas electron structure. Since they do not conduct electricity when they melt there are no ions of opposite charge. Water, a liquid @room temperature is a covalent substance. (It does not conduct electricity unless contaminated with a dissolved ionic substance)

Hx

x xx

Ox

xx

x x

Hx

xO

x

xx x

Hx

H

Covalent Bonding• Naming Covalent Compounds• Covalent compounds are named according to the numbers of each

element. The number of each element is indicated by the Latin prefix (mono, di, tri, tetra...)

• E.g.

• N2O5 dinitrogen pentoxide

• CO2 carbon dioxide

• NO nitrogen monoxide

• “ Prefix + element name” “prefix + element stem + ide”

• Normally the prefix mono is omitted from the name of the first element. The element with the most metallic is always named first.

Covalent Bonding• Naming Covalent CompoundsNote: • the final “a” or “o” of a prefix is omitted if the name of the atom or

ion being counted begins with either an a or an o.

• E.g N2O5 dinitrogen pentoxide not dinitrogen pentaoxide

– Prefixes

• Mono = 1 Hexa = 6

• Di = 2 Hepta = 7

• Tri = 3 Octa = 8

• Tetra = 4 Nano = 9

• Penta = 5 Deca = 10

metallic bonding

Summary

Summary Documents

• Summary text of this PowerPoint

• Summary Flowcharts – naming compounds – writing formulas for compounds

• Compare and contrast bonding types

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