bonding between atoms
DESCRIPTION
Bonding Between Atoms. Why do Atoms Form Bonds?. To get a stable octet of valence electrons. Called a “noble gas configuration”. Changes in Energy. Energy is released when bonds form. (exothermic) Results in lower energy, more stability Know example…. Bonding Type #1. Ionic Bonding. - PowerPoint PPT PresentationTRANSCRIPT
Bonding Between AtomsBonding Between Atoms
Why do Atoms Form Bonds?Why do Atoms Form Bonds?To get a To get a stable octetstable octet of valence electrons. of valence electrons.
Called a “noble gas configuration”Called a “noble gas configuration”
IONIC BOND = valence e- transferred
COVALENT BOND = valence e- shared
Changes in EnergyChanges in Energy
Energy is Energy is releasedreleased when bonds form. when bonds form. (exothermic)(exothermic)
Results in lower energy, more stabilityResults in lower energy, more stabilityKnow example…Know example…
Lewis Dot Diagrams of AtomsLewis Dot Diagrams of Atoms
Show valence electrons that are involved Show valence electrons that are involved in bondingin bonding
Lewis Dot Diagrams of IonsLewis Dot Diagrams of Ions
Positive Ions (cations): lose outer shell Positive Ions (cations): lose outer shell valence to get stable octet.valence to get stable octet.
Negative Ions (anions): gain electrons to Negative Ions (anions): gain electrons to complete outer shell octet.complete outer shell octet.
Ionic BondingIonic Bonding
Happens between metals Happens between metals and nonmetalsand nonmetals
Atoms Atoms Become IonsBecome Ions
Metals Lose Electrons:Metals Lose Electrons: become (+) ion become (+) ion
Ex: Mg is 2-8-2Ex: Mg is 2-8-2Loses 2 electrons to become MgLoses 2 electrons to become Mg+2+2 2-82-8
Nonmetals Gain ElectronsNonmetals Gain Electrons: : usually take top (-) chargeusually take top (-) charge
become (–) ion become (–) ion Ex: Cl is 2-8-7Ex: Cl is 2-8-7Gains 1 electron to become ClGains 1 electron to become Cl-1-1 2-8-82-8-8
Electron TransferElectron Transfer
As ions form, an exchange or As ions form, an exchange or transfertransfer of of electrons happens.electrons happens.
Lithium (metal) 2-1 Fluorine (nonmetal) 2-7
Electronegativity DifferenceElectronegativity Difference
Atoms in ionic compounds Atoms in ionic compounds
have have large differences in their EN large differences in their EN values ( > 1.7)values ( > 1.7)
The greater the EN difference, theThe greater the EN difference, the
more more “Ionic Character”.“Ionic Character”.
Ex: Ex: EN ValuesEN ValuesMetalMetal Na = 0.9Na = 0.9Nonmetal Nonmetal Cl = 3.2Cl = 3.2
Nonmetal with higher EN Nonmetal with higher EN “takes” electron(s) from metal“takes” electron(s) from metal
Positively and negatively charged ions form and Positively and negatively charged ions form and attract each other due to OPPOSITE CHARGES.attract each other due to OPPOSITE CHARGES.
Attraction forms an Attraction forms an
IONIC BONDIONIC BOND
Forming Table Salt :6 minutesForming Table Salt :6 minutes http://science360.gov/obj/video/c8b6ed58-5791-4fc1-8619-62fd8d99d9d0/atoms-bond-ionic-bondshttp://science360.gov/obj/video/c8b6ed58-5791-4fc1-8619-62fd8d99d9d0/atoms-bond-ionic-bonds
+ ion
- ion
Ionic compounds have a Ionic compounds have a uniform crystalline uniform crystalline lattice structure.lattice structure.
https://www.youtube.com/watch?v=lhC42qxk5kQ&safe=active
Can you identify an ionic compound from a Can you identify an ionic compound from a covalent?covalent?
MgBrMgBr22
Ca(NOCa(NO33))22
PP22OO55
COCO22
NaNa22SS
HH2200
Drawing Lewis Dot Drawing Lewis Dot Diagrams of Ionic Diagrams of Ionic Compounds Compounds
Do Page 7 in Do Page 7 in Bonding PacketBonding Packet
Writing Ionic FormulasWriting Ionic Formulas
Ionic Compounds are NeutralIonic Compounds are Neutral
Subscripts showSubscripts show
ratio of ions ratio of ions
Total positive andTotal positive and
negative chargesnegative charges
must balancemust balance so the so the
compound iscompound is
electrically neutral.electrically neutral.
Writing Neutral Ionic FormulasWriting Neutral Ionic Formulas Write symbols of elementsWrite symbols of elements Write the chargesWrite the charges Criss-Cross charges Criss-Cross charges if necessaryif necessary to balance the to balance the
formulaformula Put parenthesis around polyatomic ions if more than Put parenthesis around polyatomic ions if more than
one in formulaone in formula
Simplify if needed.Simplify if needed.
Tutorial on writing ionic formulas 9 minhttp://www.youtube.com/watch?v=vscoYh6m46M
Stock System for Naming Stock System for Naming Ionic CompoundsIonic Compounds
Binary:Binary:
Contain ions of 2 Contain ions of 2 elements elements
Ex:Ex: MgClMgCl22, Al, Al22OO33, ,
NaClNaCl
Naming Binary IonicsNaming Binary IonicsName metalName metalName nonmetal with “-ide” ending.Name nonmetal with “-ide” ending.
Ex: NaCl, MgBrEx: NaCl, MgBr22, CaO, Al, CaO, Al22SS33
Ternary:Ternary: Contain 3 elements Contain 3 elementsPolyatomic ionPolyatomic ion present. present.Elements inside the polyatomic ion are Elements inside the polyatomic ion are
covalently bonded (all nonmetals).covalently bonded (all nonmetals).
Thus these compounds Thus these compounds contain both ionic contain both ionic and covalent bondsand covalent bonds!!!!
Ex:Ex: NaNONaNO33, Ca, Ca33(PO(PO44))2, 2, NHNH44ClCl
Naming Ternary Ionics (with polyatomic)Naming Ternary Ionics (with polyatomic)Name MetalName MetalName polyatomic ionName polyatomic ion If two polyatomics, name them bothIf two polyatomics, name them both
When to Use a Roman NumeralWhen to Use a Roman Numeral
Roman numerals are used when the Roman numerals are used when the metalmetal can have more than one possible charge.can have more than one possible charge.
Roman numeral indicates the charge the Roman numeral indicates the charge the metal takes in that compound and metal takes in that compound and must be must be indicated in the nameindicated in the name
Ex:Ex: NiBrNiBr22 Nickel II BromideNickel II Bromide
NiBrNiBr33 Nickel III Bromide Nickel III Bromide
Crash Course Chemistry: NomenclatureCrash Course Chemistry: Nomenclature (only watch first 6 minutes, skip section on naming acids for now)(only watch first 6 minutes, skip section on naming acids for now)
http://www.youtube.com/watch?http://www.youtube.com/watch?v=mlRhLicNo8Qv=mlRhLicNo8Q
Properties of Ionic Properties of Ionic CompoundsCompounds
High Melting PointHigh Melting PointAttraction between theAttraction between theions is very strong.ions is very strong.
Requires a lot of heatRequires a lot of heatenergy to separateenergy to separateions and make solidions and make solidcrystal melt.crystal melt.
Higher MP than covalentsHigher MP than covalents
Solubility in WaterSolubility in Water
Most ionics will Most ionics will dissolve in water, or dissolve in water, or be be ““solublesoluble”.”.
When dissolved in water When dissolved in water they are “aqueous”they are “aqueous”
Ex: NaCl (aq)Ex: NaCl (aq)
Water is a “polar molecule”Water is a “polar molecule”. . Acts like a magnet to pull ions apart and into Acts like a magnet to pull ions apart and into
solution.solution. Ions are now “dissociated” or “hydrated” ions.Ions are now “dissociated” or “hydrated” ions.
http://youtu.be/EBfGcTAJF4ohttp://youtu.be/EBfGcTAJF4o
ConductivityConductivity
Ionic compounds Ionic compounds conduct when ions conduct when ions are are ““mobilemobile”” or free or free to move about.to move about.
ConductivityConductivity Ionic compounds conduct when:Ionic compounds conduct when:
Molten (melted/liquid) Molten (melted/liquid) (l)(l)Aqueous Aqueous (aq)(aq)
Note: They Note: They DO NOT DO NOT conduct conduct when solid as the ions are locked when solid as the ions are locked in place.in place.
Covalent Compounds in water Covalent Compounds in water do not conductdo not conduct
Dancing Queen: Song about Ionic vs Dancing Queen: Song about Ionic vs Covalent BondingCovalent Bonding
http://www.youtube.com/watch?v=QIfTT-http://www.youtube.com/watch?v=QIfTT-_-xLo_-xLo
Crash Course: Atomic Hookups Crash Course: Atomic Hookups http://www.youtube.com/watch?http://www.youtube.com/watch?
v=QXT4OVM4vXIv=QXT4OVM4vXI