Chemical BondingChemical Bonding

No one wants to be aloneNo one wants to be alone

Why atoms bondWhy atoms bond

Most atoms are not found alone in quantity Most atoms are not found alone in quantity in the universe, they are bonded to other in the universe, they are bonded to other atomsatoms

All atoms except the ones in Group 18 (the All atoms except the ones in Group 18 (the Noble Gases) have an Noble Gases) have an unstableunstable electron electron configurationconfiguration

Atoms will gain, lose, or share valence Atoms will gain, lose, or share valence electrons until they become stableelectrons until they become stable

Rule of OctetRule of Octet

The major groups of the Periodic Table The major groups of the Periodic Table ((Groups 1, 2, 13, 14, 15, 16, 17Groups 1, 2, 13, 14, 15, 16, 17) will gain, ) will gain, lose, or share electrons until they have 8 lose, or share electrons until they have 8 or 0 valence electronsor 0 valence electrons

0 valence electrons means that layer is 0 valence electrons means that layer is stripped and the full inner layer is stripped and the full inner layer is exposed, making them stableexposed, making them stable

Counting outer shell electronsCounting outer shell electrons

An Electron-Dot Diagram allows us to An Electron-Dot Diagram allows us to draw atoms and show their valence draw atoms and show their valence electron configurationelectron configurationWrite the element’s symbolWrite the element’s symbolBegin placing dots around the symbol equal Begin placing dots around the symbol equal

to the number of outer-shell electronsto the number of outer-shell electrons1 to a side, then double up1 to a side, then double up

Oxidation NumbersOxidation Numbers

The charge on the atom after an atom The charge on the atom after an atom gains, loses, or shares electrons to gains, loses, or shares electrons to become stablebecome stable

This positive or negative number tells you This positive or negative number tells you how many electrons the atom gained or how many electrons the atom gained or lostlost

+1 +2 +3 ±4 -3-2-1 Ø

How many valence electrons does How many valence electrons does Magnesium have?Magnesium have?

1.1. 11

2.2. 22

3.3. 33

4.4. 44

5.5. 55

How many valence electrons will How many valence electrons will Magnesium gain, lose, or share?Magnesium gain, lose, or share?

1.1. Lose 1Lose 1

2.2. Gain 1Gain 1

3.3. Lose 2Lose 2

4.4. Gain 2Gain 2

5.5. Gain 6Gain 6

What is Magnesium’s Oxidation What is Magnesium’s Oxidation Number?Number?

1.1. +1+1

2.2. -1-1

3.3. +2+2

4.4. -2-2

5.5. -6-6

What is Chlorine’s Oxidation Number?What is Chlorine’s Oxidation Number?

1.1. +1+1

2.2. -1-1

3.3. +2+2

4.4. -2-2

5.5. +7+7

What is Potassium’s Oxidation What is Potassium’s Oxidation Number?Number?

1.1. +1+1

2.2. -1-1

3.3. +2+2

4.4. -2-2

5.5. -3-3

What is Sulphur’s Oxidation Number?What is Sulphur’s Oxidation Number?

1.1. +1+1

2.2. -1-1

3.3. +2+2

4.4. -2-2

5.5. +3+3

IonsIons

When an atom gains or loses electrons, it When an atom gains or loses electrons, it now has a now has a chargecharge

A charged particle is called an A charged particle is called an ionionAtoms losing electrons have a positive charge Atoms losing electrons have a positive charge

and are called and are called anionsanionsAtoms gaining electrons have a negative Atoms gaining electrons have a negative

charge and are called charge and are called cationscations

Types of Chemical BondingTypes of Chemical Bonding

Ionic BondsIonic Bonds are formed: are formed:When one atom (usually a metal) loses 1 or When one atom (usually a metal) loses 1 or

more electrons andmore electrons andAnother atom (usually a nonmetal) gains 1 or Another atom (usually a nonmetal) gains 1 or

more electronsmore electronsThe attraction between positive and negative The attraction between positive and negative

ions (opposites attract) causes the atoms to ions (opposites attract) causes the atoms to stick together with an incredible amount of stick together with an incredible amount of electromagnetic forceelectromagnetic force

More on Ionic BondsMore on Ionic Bonds

Ionic BondsIonic BondsAre created from elements on opposite sides Are created from elements on opposite sides

of the Periodic Tableof the Periodic TableHave unusually high melting and boiling Have unusually high melting and boiling

pointspointsAre usually solids at room temperatureAre usually solids at room temperatureDissolve into aqueous solutions easily Dissolve into aqueous solutions easily

(soluble or miscible)(soluble or miscible)

Types of Chemical BondingTypes of Chemical Bonding

Covalent BondsCovalent Bonds are formed: are formed:When two or more atoms share outer-shell When two or more atoms share outer-shell

electrons to complete their octetelectrons to complete their octetOnce the sharing begins, the atoms can not Once the sharing begins, the atoms can not

go their different ways except to take the go their different ways except to take the electrons that they were sharing and bond to electrons that they were sharing and bond to another atomanother atom

More on Covalent BondsMore on Covalent Bonds

Covalent BondsCovalent BondsAre created from elements somewhat close to Are created from elements somewhat close to

each other on the Periodic Tableeach other on the Periodic TableCan be liquids or solids at room temperatureCan be liquids or solids at room temperatureMany do not dissolve into aqueous solutions Many do not dissolve into aqueous solutions

easily (immiscible)easily (immiscible)

Types of Chemical BondingTypes of Chemical Bonding

Metallic BondsMetallic Bonds are formed: are formed:When one or more metals combine (alloy)When one or more metals combine (alloy)The positive nuclei arrange into a lattice, while The positive nuclei arrange into a lattice, while

the electrons flow freely from atom to atomthe electrons flow freely from atom to atomSometimes called a “Sea of Electrons”Sometimes called a “Sea of Electrons”

More on Metallic BondsMore on Metallic Bonds

Metallic BondsMetallic BondsExplains why metals are lustrous and good Explains why metals are lustrous and good

conductors of electricity (the flow of electrons)conductors of electricity (the flow of electrons)Are solids at room temperatureAre solids at room temperatureMay lose electrons to substances outside of May lose electrons to substances outside of

the bond, causing corrosion or oxidation of the bond, causing corrosion or oxidation of the metals (rusting)the metals (rusting)Usually with Oxygen, forms a nonmetallic Usually with Oxygen, forms a nonmetallic

compound and substantially weakens the metalscompound and substantially weakens the metals

Bonds and PolarityBonds and Polarity

ElectronegativityElectronegativityDescribes how “stingy” an atom is towards Describes how “stingy” an atom is towards

electronselectrons Increases as you move up and right on the Increases as you move up and right on the

Periodic TablePeriodic Table

General ReactivityGeneral Reactivity

Reactivity increases for Metals as you move Reactivity increases for Metals as you move down and left from the stair-stepdown and left from the stair-step

Reactivity increases for Nonmetals as you Reactivity increases for Nonmetals as you move up and right from the stair-stepmove up and right from the stair-step

Fluorine is the most reactive nonmetal, Fluorine is the most reactive nonmetal, Cesium or Francium is the most reactive Cesium or Francium is the most reactive metalmetal

Covalent Bonds and PolarityCovalent Bonds and Polarity

Polar Covalent BondsPolar Covalent BondsFormed when the atoms in a sharing Formed when the atoms in a sharing

relationship don’t share evenlyrelationship don’t share evenlyA slight negative charge appears on the end A slight negative charge appears on the end

of the molecule with the “Stingy” atomof the molecule with the “Stingy” atomA slight positive charge appears on the end of A slight positive charge appears on the end of

the molecule with the “Generous” atomthe molecule with the “Generous” atom

Solubility and PolaritySolubility and Polarity

““Like dissolves like”Like dissolves like” Polar molecules can dissolve other polar moleculesPolar molecules can dissolve other polar molecules Polar molecules can dissolve ionic moleculesPolar molecules can dissolve ionic molecules Nonpolar molecules can dissolve other nonpolar Nonpolar molecules can dissolve other nonpolar

moleculesmolecules

Polar substances can not dissolve nonpolar Polar substances can not dissolve nonpolar substancessubstances

Nonpolar substances can not dissolve polar Nonpolar substances can not dissolve polar substancessubstances

REVIEWREVIEWWhy atoms bondWhy atoms bondRule of OctetRule of Octet

Exceptions!Exceptions!Electron-Dot DiagramsElectron-Dot DiagramsOxidation NumbersOxidation Numbers IonsIons Ionic BondsIonic BondsCovalent BondsCovalent Bonds

Metallic BondsMetallic BondsElectronegativityElectronegativityReactivityReactivityPolarityPolaritySolubilitySolubility

Most atoms bond becauseMost atoms bond because

1.1. They’re lonelyThey’re lonely

2.2. They have too many valence They have too many valence electronselectrons

3.3. They have too few valence They have too few valence electronselectrons

What number of outer shell electrons is What number of outer shell electrons is stable for most atoms?stable for most atoms?

1.1. 22

2.2. 88

3.3. 00

4.4. 66

5.5. 2 & 82 & 8

6.6. 8 & 08 & 0

7.7. 0 & 60 & 6

What do we use to show just the What do we use to show just the valence electrons for an atom?valence electrons for an atom?

1.1. Bohr modelBohr model

2.2. Wave modelWave model

3.3. Scale modelScale model

4.4. Electron Dot DiagramElectron Dot Diagram

What is the name for an atom that has What is the name for an atom that has gained or lost electrons?gained or lost electrons?

1.1. PositronPositron

2.2. IonIon

3.3. NegatronNegatron

4.4. MegatronMegatron

How do atoms become stable?How do atoms become stable?

1.1. Gain electronsGain electrons

2.2. Lose electronsLose electrons

3.3. Share electronsShare electrons

4.4. All of the aboveAll of the above

Atoms that have gained electrons are Atoms that have gained electrons are called?called?

1.1. IonIon

2.2. AnionAnion

3.3. PositronPositron

4.4. CationCation

Ionic bonds are held together by which Ionic bonds are held together by which force?force?

1.1. Strong nuclearStrong nuclear

2.2. Weak nuclearWeak nuclear

3.3. ElectromagneticElectromagnetic

4.4. GravityGravity

Atoms that have lost electrons are Atoms that have lost electrons are called?called?

1.1. IonIon

2.2. AnionAnion

3.3. PositronPositron

4.4. CationCation

Covalent bonds are formed when Covalent bonds are formed when atomsatoms

1.1. Gain electronsGain electrons

2.2. Lose electronsLose electrons

3.3. Share electronsShare electrons

4.4. All of the aboveAll of the above

Atoms far apart on the Periodic Table Atoms far apart on the Periodic Table will usually bond will usually bond

1.1. IonicallyIonically

2.2. CovalentlyCovalently

3.3. MetallicallyMetallically

4.4. They will not bondThey will not bond

Groups 3 – 12 will use which method to Groups 3 – 12 will use which method to bond?bond?

1.1. Ionic bondingIonic bonding

2.2. Covalent bondingCovalent bonding

3.3. Metallic bondingMetallic bonding

4.4. They will not bondThey will not bond

Which part of a metallic bond explains Which part of a metallic bond explains why metals are lustrous and good why metals are lustrous and good

conductor of electricity?conductor of electricity?1.1. Nuclei in a latticeNuclei in a lattice

2.2. ““Sea of electrons”Sea of electrons”

3.3. The density of the nucleiThe density of the nuclei

4.4. Metals aren’t good conductorsMetals aren’t good conductors

Atoms with a strong attraction to their Atoms with a strong attraction to their electrons are said to be electrons are said to be

1.1. PositronicPositronic

2.2. GravometricGravometric

3.3. ThaleonicThaleonic

4.4. ElectronegativeElectronegative

What is the most reactive nonmetal?What is the most reactive nonmetal?

1.1. ChlorineChlorine

2.2. FluorineFluorine

3.3. OxygenOxygen

4.4. SulphurSulphur

A covalent bond where the atoms do A covalent bond where the atoms do not share evenly is called a not share evenly is called a

1.1. Polar BondPolar Bond

2.2. Equatorial BondEquatorial Bond

3.3. Longitudinal BondLongitudinal Bond

4.4. Latitudinal BondLatitudinal Bond

What is the rule concerning how polar What is the rule concerning how polar and nonpolar bonds react? and nonpolar bonds react?

1.1. ““Opposites Attract”Opposites Attract”

2.2. ““Like Repel”Like Repel”

3.3. ““Like dissolves like”Like dissolves like”

4.4. ““Bless the Maker and his Bless the Maker and his Water”Water”

Most atoms are found _____ in nature. Most atoms are found _____ in nature.

1.1. BondedBonded

2.2. UnbondedUnbonded

3.3. FreeFree

4.4. Free-rangeFree-range

What is the most electronegative What is the most electronegative (stingiest for electrons) element? (stingiest for electrons) element?

1.1. OxygenOxygen

2.2. ChlorineChlorine

3.3. FluorineFluorine

4.4. ArsenicArsenic

How does oxidation affect a metal? How does oxidation affect a metal?

1.1. Strengthens itStrengthens it

2.2. Weakens itWeakens it

3.3. Makes it usefulMakes it useful

A covalent bond where the atoms A covalent bond where the atoms share evenly is called a share evenly is called a

1.1. Polar BondPolar Bond

2.2. Nonpolar BondNonpolar Bond

3.3. Ionic BondIonic Bond

4.4. Metallic BondMetallic Bond

Draw the Electron-Dot diagram Draw the Electron-Dot diagram for Selenium (Group 16, Period for Selenium (Group 16, Period

4, Atomic # 34).4, Atomic # 34).

Which group of elements loses Which group of elements loses electrons most easily?electrons most easily?

1. Group 31. Group 32. Group 152. Group 153. Group 13. Group 1

4. Group 174. Group 17

In an electron-dot diagram of In an electron-dot diagram of oxygen (O), how many dots should oxygen (O), how many dots should

be drawn around the element’s be drawn around the element’s symbol? WHY?symbol? WHY?

Explain why the Noble Gases Explain why the Noble Gases (Group 18) will not bond (Group 18) will not bond ionically, covalently, or ionically, covalently, or

metallically.metallically.

Compare a covalent bond and an Compare a covalent bond and an ionic bond.ionic bond.

Describe why water will dissolve Describe why water will dissolve sugar easily, but sugar will not sugar easily, but sugar will not

dissolve in cooking oil.dissolve in cooking oil.