Ch 7 PowerPoint Notes Ch 7 PowerPoint Notes

Section 7.1 - IonsSection 7.1 - Ions

OBJECTIVES:OBJECTIVES:

Determine the number Determine the number of of valence electronsvalence electrons in in an atom of a an atom of a representative element.representative element.

Section 7.1 - IonsSection 7.1 - Ions

OBJECTIVES:OBJECTIVES:

Explain how the octet Explain how the octet rule applies to atoms of rule applies to atoms of metallic and nonmetallic metallic and nonmetallic elements.elements.

Section 7.1 - IonsSection 7.1 - Ions

OBJECTIVES:OBJECTIVES:

Describe how Describe how cationscations and anions form.and anions form.

Why do some elements react to Why do some elements react to form compounds and others do not?form compounds and others do not?

Is there any way to predict if atoms Is there any way to predict if atoms might react with each other?might react with each other?

Is there any way to predict what Is there any way to predict what chemical formulas might be formed?chemical formulas might be formed?

Ionic and Metallic BondingIonic and Metallic Bonding

Na 1+, Na +1 or Na+ = cation , missing 1 e-

O2- = anion, gained 2 e-

(the number is the charge on ion, not # of e- gained or lost,, i.e., +1 means 1 electron lost, not 1 gained.)

Ion definitionsIon definitionsValence electronsValence electrons: Outermost electrons. The : Outermost electrons. The

ss and and pp electrons in the outer energy level. electrons in the outer energy level. The highest occupied energy level.The highest occupied energy level.

Core electronsCore electrons:: are those in the energy levels are those in the energy levels below.below.

IonIon:: An atom that has lost or gained an electron. An atom that has lost or gained an electron. Ions have a + or - charge. Ions have a + or - charge.

(Atoms are always neutral, # of p+ = # of e(Atoms are always neutral, # of p+ = # of e--)) CationCation:: Positive Ion or metals, gained e Positive Ion or metals, gained e--.. AnionAnion:: Negative Ion or non-metals, Lost e Negative Ion or non-metals, Lost e--..

Valence Electrons are…?Valence Electrons are…?The electrons responsible for the The electrons responsible for the

chemical properties of atoms, and chemical properties of atoms, and are those in the are those in the outerouter energy level. energy level.

Valence electronsValence electrons - The - The ss and and pp electrons in the outer energy levelelectrons in the outer energy levelthe highest occupied energy levelthe highest occupied energy level

Core electronsCore electrons – are those in the – are those in the energy levels below.energy levels below.

Keeping Track of ElectronsKeeping Track of Electrons Atoms in the same column (group)...Atoms in the same column (group)...

1)1) Have the same outer electron Have the same outer electron configuration.configuration.

2)2) Have the same valence electrons.Have the same valence electrons. The number of valence electrons are The number of valence electrons are

easily determined. It is the easily determined. It is the group group numbernumber for representative. for representative.

Group 2A: Be, Mg, Ca, etc.Group 2A: Be, Mg, Ca, etc. have 2 valence electronshave 2 valence electrons

Group 8A, Noble gases has 8.Group 8A, Noble gases has 8.

Electron Dot diagrams Electron Dot diagrams are…are… DEF: Shows the 8 valence electrons as dot DEF: Shows the 8 valence electrons as dot

pairs around the chemical symbol.pairs around the chemical symbol. A way of showing & keeping track A way of showing & keeping track

of valence electrons.of valence electrons. How to write them?How to write them? Write the symbol - it represents the nucleus Write the symbol - it represents the nucleus

and inner (core) electronsand inner (core) electrons Put one dot for each valence electron (Put one dot for each valence electron (8 8

maximummaximum)) They don’t pair up until they have to (Hund’s They don’t pair up until they have to (Hund’s

rule). Do 4 singles before pairs.rule). Do 4 singles before pairs.

X

Electron Dot diagramsElectron Dot diagramsSingle dots can be on any side.Single dots can be on any side.

1A 2A 3A 4A

5A 6A 7A 8A

Valence e- Valence e- highest electron highest electron energy level of an atomenergy level of an atom

((nns s nnp…where n is the same numberp…where n is the same number))

Nitrogen 1sNitrogen 1s22 2s2s22 2p 2p33 5 Valence e- 5 Valence e-

e- dot structures show only e- dot structures show only valence e-valence e-

(single per side/then pair up)(single per side/then pair up)2 dots Mg –[Ne]3s2 dots Mg –[Ne]3s22 3p 3p0 0

Need to Memorize!! EASY!Need to Memorize!! EASY!

valence e-valence e- determine the determine the chemical properties of an chemical properties of an

elementelement

Alkali metals (1 ve-) - Alkali metals (1 ve-) - nnss11 nnpp0 0

Remember s, p, d, f blocksRemember s, p, d, f blocks

1234567

1234567

S p1S1 1S2

2S1 2S2

3S1 3S2

2p1 2p2 2p32p4 2p5 2p6

Write the e dot structuresWrite the e dot structures  O = 1sO = 1s22 2s2s22 2p 2p44

  Ne = Ne =   Na = Na =

Write the e dot structuresWrite the e dot structures  

O = 1sO = 1s22 2s2s22 2p 2p44

  Ne = 1sNe = 1s22 2s2s22 2p 2p66

  Na = 1sNa = 1s22 2s 2s22 2p 2p66 3s3s11 3p 3p

e dot structures – show valence e dot structures – show valence e- as dotse- as dots

  O = 1sO = 1s22 2s2s22 2p 2p44

  Ne = 1sNe = 1s22 2s2s22 2p 2p66

  Na = 1sNa = 1s22 2s 2s22 2p 2p66 3s3s11 3p 3p

octet rule – ions tend to have octet rule – ions tend to have pseudo noble gas configuration pseudo noble gas configuration

(8 valence e-)(8 valence e-)full s and p orbitals full s and p orbitals

Formation of CationsFormation of CationsMetals Metals loselose electrons electrons to attain a noble to attain a noble

gas configuration.gas configuration.They make positive ions They make positive ions (cations)(cations)If we look at the electron configuration, If we look at the electron configuration,

it makes sense to lose electrons:it makes sense to lose electrons:Na Na 1s1s222s2s222p2p663s3s11 1 valence electron 1 valence electronNaNa1+1+ 1s1s222s2s222p2p66 This is a noble gas This is a noble gas

configuration with 8 electrons in the configuration with 8 electrons in the outer level.outer level.

Electron Dots For CationsElectron Dots For CationsMetals will have few valence electrons Metals will have few valence electrons

(usually 3 or less); calcium has only 2 (usually 3 or less); calcium has only 2 valence electronsvalence electrons

Ca

Electron Dots For CationsElectron Dots For CationsMetals will have few valence electronsMetals will have few valence electronsMetals will Metals will lose the valence electronslose the valence electrons

Ca

Electron Dots For CationsElectron Dots For CationsMetals will have few valence electronsMetals will have few valence electronsMetals will Metals will lose the valence electronslose the valence electronsForming positive ionsForming positive ions

Ca2+NO DOTS are now shown for the cation.

This is named the “calcium ion”.

Electron Configurations: Electron Configurations: AnionsAnionsNonmetals Nonmetals gaingain electrons electrons to attain to attain

noble gas configuration.noble gas configuration.They make negative ions They make negative ions (anions)(anions)SS = = 1s1s222s2s222p2p663s3s223p3p44 = 6 valence = 6 valence

electronselectronsSS2-2- = = 1s1s222s2s222p2p663s3s223p3p66 = noble gas = noble gas

configuration. configuration. Halide ionsHalide ions are ions from chlorine or are ions from chlorine or

other halogens that gain electronsother halogens that gain electrons

Electron Dots For AnionsElectron Dots For AnionsNonmetals will have many valence Nonmetals will have many valence

electrons (usually 5 or more)electrons (usually 5 or more)They will They will gaingain electrons to fill outer shell. electrons to fill outer shell.

P 3-(This is called the “phosphide ion”, and should show dots)

Stable Electron ConfigurationsStable Electron Configurations All atoms react to try and achieve a All atoms react to try and achieve a

noble gas configuration.noble gas configuration. Noble gases have 2 s and 6 p electrons.Noble gases have 2 s and 6 p electrons. 8 valence electrons = already stable!8 valence electrons = already stable! This is the This is the octet ruleoctet rule (8 in the outer level (8 in the outer level

is particularly stable).is particularly stable).

Ar

ATOMATOMNa = 1sNa = 1s22 2s 2s22 2p 2p66 3s3s11 3p 3p00

IONIONNaNa+1+1 = 1s = 1s22 2s2s22 2p 2p66

a. What is the charge of an e-?a. What is the charge of an e-?

b. What is the e- config for N b. What is the e- config for N 3-3- ion? ion?

c. How many e- does (B) have?c. How many e- does (B) have?

d. how many valence e- does (B) have?d. how many valence e- does (B) have?

  

Common IONIC CHARGES Common IONIC CHARGES OF OF REPRESENTATIVE ELEMENTSREPRESENTATIVE ELEMENTSAdd to periodic tableAdd to periodic table

11+1+1

2 2 +2+2

1313+3+3

1414 1515-3-3

16 16 -2-2

17 17 -1-1

Li Li NaNaKK

RbRbCsCs

Be Be MgMgCaCaSrSrBaBa

      AlAl

N N PPAsAs

O O SS

SeSe

F F ClClBrBrII

Why don’t the noble gases form Why don’t the noble gases form ions?ions?

When writing SWhen writing S2-2-, what does , what does the 2- indicate?the 2- indicate?

Does this ion have more or Does this ion have more or less e than the original atom?less e than the original atom?

Section 7.2 Ionic Bonds and Section 7.2 Ionic Bonds and Ionic CompoundsIonic Compounds

OBJECTIVES:OBJECTIVES:

ExplainExplain the electrical the electrical charge of an ionic charge of an ionic compound.compound.

Section 7.2 Ionic Bonds and Section 7.2 Ionic Bonds and Ionic CompoundsIonic Compounds

OBJECTIVES:OBJECTIVES:

DescribeDescribe three three properties of ionic properties of ionic compounds.compounds.

Ionic Compounds – Ionic Compounds – compounds formed from compounds formed from

cations and anionscations and anions Usually a metal and a Usually a metal and a

nonmetal nonmetal (the charges always cancel)(the charges always cancel)

NaNa++, Cl, Cl-- = NaCl = NaCl

Ionic BondingIonic BondingAnions and cations are held together Anions and cations are held together

by by opposite chargesopposite charges (+ and -) (+ and -)Ionic compounds are called Ionic compounds are called saltssalts..Simplest Simplest ratioratio of elements in an ionic of elements in an ionic

compound is called the compound is called the formula unitformula unit..The bond is formed through the The bond is formed through the

transfer of electrons (lose and gain)transfer of electrons (lose and gain)Electrons are transferred Electrons are transferred to achieve to achieve

noble gas configuration (Octet Rule).noble gas configuration (Octet Rule).

Ionic CompoundsIonic Compounds

1)1) Also called Also called SALTSSALTS

2)2) Made from: a Made from: a CATIONCATION with an with an ANIONANION (or literally (or literally from a from a metalmetal combining combining with a with a nonmetalnonmetal))

Ionic BondingIonic Bonding

Na ClThe metal (sodium) tends to lose its one electron from the outer level.

The nonmetal (chlorine) needs to gain one more to fill its outer level, and will accept the one electron that sodium is going to lose.

Ionic BondingIonic Bonding

Na+ Cl -

Note: Remember that NO DOTS are now shown for the cation!

Chemical formula Chemical formula = number of = number of atoms in a atoms in a

formula unitformula unit of an of an ionic compound ionic compound (and not the charges (and not the charges

on the ions)on the ions)

Formula unit = Formula unit = NaClNaCl

Ionic BondingIonic Bonding

All the electrons must be accounted forAll the electrons must be accounted for, , and and eacheach atom will have a noble gas atom will have a noble gas configuration (which is stable).configuration (which is stable).

Ca P

Lets do an example by combining calcium and phosphorus:

Ionic BondingIonic Bonding

Ca P

Ionic BondingIonic Bonding

Ca2+ P

Ionic Bonding

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca

Ionic Bonding

Ca2+ P 3-

Ca P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+P

3-

Ca2+

Ionic Bonding

= Ca3P2Formula Unit

This is a chemical formula, which shows the kinds and numbers of atoms in the smallest representative particle of the substance.

For an ionic compound, the smallest representative particle is called a: Formula Unit

Chemical formula Chemical formula = number of = number of atoms in a atoms in a

formula unitformula unit of an of an ionic compound ionic compound (and not the charges (and not the charges

on the ions)on the ions)

Formula unit = Formula unit = NaClNaCl

Ionic compounds are Ionic compounds are usually brittle solids usually brittle solids

at room temperature, at room temperature, with repeating with repeating

internal 3-D crystal internal 3-D crystal patterns, that have patterns, that have high melting pointshigh melting points

Ionic bonds – electrostatic Ionic bonds – electrostatic force that holds compound force that holds compound

togethertogether

What number of each ion do What number of each ion do you need to make an ionic you need to make an ionic compound?compound?

Na, FNa, F

Na, SNa, S

Al, NAl, N

What number of each ion do What number of each ion do you need to make an ionic you need to make an ionic compound?compound?

Na, FNa, F NaFNaF Na, SNa, S NaNa22SS

Al, NAl, N AlNAlN

Metal bonds Metal bonds

valence electrons of metal atoms valence electrons of metal atoms can be modeled as a sea of can be modeled as a sea of

electrons electrons Metallic bonds Metallic bonds = free-floating = free-floating

valence electrons attracted to the valence electrons attracted to the positively charged metal ionspositively charged metal ions

Alloys Alloys are mixtures composed of are mixtures composed of two or more elements, at leasttwo or more elements, at least

one of which is a metalone of which is a metal

Quick review questionsQuick review questions Can have everyone stand up and answers following q’s to sit down.Can have everyone stand up and answers following q’s to sit down.

An ionic compound is usually An ionic compound is usually formed between a metal and a formed between a metal and a

__?__?

How many dots around a sodium How many dots around a sodium atom?atom?

How many dots around a sodium How many dots around a sodium atom?atom?

What is the charge on a sodium What is the charge on a sodium atom?atom?

What is the charge on a sodium What is the charge on a sodium ion?ion?

What are some ionic compounds What are some ionic compounds formed with sodium?formed with sodium?

What is the charge on an aluminum What is the charge on an aluminum ion?ion?

What are some ionic compounds What are some ionic compounds formed with Aluminum?formed with Aluminum?