Bonding

BondingWhy bonding????Nature prefers stabilityAtoms that exist alone are unstableAtoms bond with other atoms to become more stableThis is why we rarely find lone atoms in natureDiatomics H2, N2, O2, F2, Cl2, Br2, I2They will bind with other atoms to form moleculesShare or transfer valence electronsWhy bonding????Binding causes valence electrons to redistributeThis makes the atoms more stable, which is preferredSTABILITY!!!! Drives bondingWhat is a bond???The mutual attraction between valence electrons of one atom and nuclei of another atom

Types of bondsThe arrangement of electrons determines the type of bond3 typesIonicCovalentmetallic

Ionic bondingElectrical attraction between cation and anion and transfer of an electronBetween a metal and nonmetal One form L and one from R side of PTMetal donates e- to nonmetal

Form clusters of alternating charge

Covalent BondingTwo non metals SHARE a pair of electronsBoth will obtain an octetElectrons will be shared equally between the two atoms

Covalent BondingMetallicSpecial type of covalent bondBetween two or more metal atomsElectrons become delocalizedsea of electrons

Covalent BondingMetallicStrength depends on nuclear charge and number of electrons sharedMore electrons that are shared, stronger the bondNC hard to measure Can use heat of vaporization amount of energy required to turn metal into a gas

Determining Bond TypesBonds in nature are never purely covalent or ionic somewhere in the middleNon-polar covalentPolar covalentIonicCan determine by looking at electronegativityDetermining Bond TypesElectronegativity measure of an atoms ability to steal electronsThe difference in electronegativites will tell us which bond type exists between the atoms

Non-Polar CovalentEN is 0.0 0.3, 0 5% ionic characterThe shared electrons and charge is evenly distributed between bonded atomsPolar-CovalentEN 0.3 1.67, 5-50% ionic characterPolar one of the atoms has greater ownership of the shared pair of electronsUnequal sharing of e- Unequal share of e- produces a dipoleCompound has areas of partial (+) and partial (-) chargePartial is indicated by + or -Polar CovalentWater!!

IonicEN 1.67- 4.0, 50 100% ionic characterValence electrons from one atom are transferred to another atomTwo ions are formed (cation and anion)Attract one another

Lets PracticeUse electronegativity differences to classify bonding between chlorine, Cl (EN = 3.0), and the following elementsCalcium, Ca (EN = 1.0)Oxygen, O (EN = 3.5)Bromine, Br (EN = 2.8)Indicate which atom is more negative