Chemical BondsChemical Bonds Section 2 - Types of BondsSection 2 - Types of Bonds

Ionic BondingIonic Bonding

To reach a To reach a stablestable energy level, energy level, atoms lose or atoms lose or gain electronsgain electrons. .

An atom is An atom is neutral neutral but will become a but will become a charged charged atomatom if there is a if there is a transfer of electronstransfer of electrons

When an atom When an atom loses or gains an electronloses or gains an electron, it , it becomes an becomes an ionion..

Ion – Ion – charged (atom) particlecharged (atom) particle that has either that has either fewer or more electronsfewer or more electrons than it has than it has protonsprotons

Ionic BondingIonic Bonding

Negative ion – has Negative ion – has more electronsmore electrons than than protonsprotons

Ionic BondingIonic Bonding

Positive ion- has Positive ion- has more protonsmore protons than than electronselectrons

Ionic BondIonic Bond

bonding that involves a transfer of bonding that involves a transfer of electronselectrons

forms when ions attract each other and forms when ions attract each other and form a compoundform a compound

force of attraction between a positive ion force of attraction between a positive ion and a negative ionand a negative ion

Ionic AnimationIonic Animation

CLICK CLICK http://facstaff.gpc.edu/~pgore/PhysicalSciehttp://facstaff.gpc.edu/~pgore/PhysicalScience/ionic_bond_animation.gifnce/ionic_bond_animation.gif

Electron - dot diagramElectron - dot diagram

drawing that uses the chemical symbol for drawing that uses the chemical symbol for an element surround by a an element surround by a series of dotsseries of dots to to show the electron bonding taking place. show the electron bonding taking place. The dots represent the The dots represent the valence electronsvalence electrons

also called Lewis Dot Structure/diagramalso called Lewis Dot Structure/diagram

Lewis Dot or Electron DotLewis Dot or Electron Dot

Covalent BondingCovalent Bonding

A lot of A lot of energyenergy is required for an atom to is required for an atom to lose or gain electronslose or gain electrons

Example: elements in Group 14 have Example: elements in Group 14 have four four electrons in their outermost level – it is electrons in their outermost level – it is easier for these elements to become easier for these elements to become stable by stable by sharing electronssharing electrons

Covalent BondingCovalent Bonding

bonding in which electrons are bonding in which electrons are sharedshared rather than transferredrather than transferred

The attraction between The attraction between electronselectrons and the and the positively charged positively charged nucleusnucleus of the atoms of the atoms hold the atoms togetherhold the atoms together

Covalent AnimationCovalent Animation

CLICK CLICK http://facstaff.gpc.edu/~pgore/PhysicalSciehttp://facstaff.gpc.edu/~pgore/PhysicalScience/covalent_bond_animation.gifnce/covalent_bond_animation.gif

http://www.physics-edu.org/nitrogen_triple_bond.gif

MoleculeMolecule

smallest combination of atoms formed by smallest combination of atoms formed by a a covalent bondcovalent bond

Equal and Unequal Equal and Unequal Electron SharingElectron Sharing

Electrons are not always shared equally Electrons are not always shared equally the nucleus of some atoms will attract the nucleus of some atoms will attract electrons more strongly and electrons will electrons more strongly and electrons will stay closer to that atom’s nucleusstay closer to that atom’s nucleus

Nonpolar Molecules (Equal)Nonpolar Molecules (Equal) When two atoms that are exactly alike When two atoms that are exactly alike

form a covalent bond, they form a covalent bond, they share share the the bonding electrons equally. In a bonding electrons equally. In a nonpolar nonpolar moleculemolecule,, the electrons are the electrons are shared equallyshared equally in the bondin the bond

Examples OExamples O22, CO, CO22, Cl, Cl22

Polar Molecule (Unequal)Polar Molecule (Unequal)

When one atom’s nucleus has a When one atom’s nucleus has a stronger forcestronger force, , electrons will stay electrons will stay closercloser to that atom. to that atom.

Examples: Examples:

Water HWater H22OO

Carbon monoxide COCarbon monoxide CO

Ammonia gas Ammonia gas NHNH33

Water MoleculeWater Molecule

The oxygen atom forms a covalent bond The oxygen atom forms a covalent bond with each hydrogen atomwith each hydrogen atom The The oxygenoxygen atom has a atom has a stronger stronger attractionattraction for the bonding electrons – the for the bonding electrons – the electrons spend more time closer to the electrons spend more time closer to the oxygen atom.oxygen atom. This gives the This gives the oxygenoxygen atom a partial atom a partial negativenegative charge and the charge and the hydrogenhydrogen a a partial partial positivepositive charge charge

Water Molecule Water Molecule (cont.)(cont.)

Because the water molecule has an end Because the water molecule has an end that is partially positive and an end that is that is partially positive and an end that is partially negative, partially negative, water is a water is a polarpolar

molecule.molecule. Polar means “having Polar means “having opposite ends”opposite ends”

**This polarity helps give water the **This polarity helps give water the structure to support life (cell systems)structure to support life (cell systems)

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