Chap 15: Ionic BondingDo Not Write this Slide

Standard:PS2D: Ions are produced when atoms or molecules lose or gain electrons,

thereby gaining a positive or negative electrical charge. Ions of opposite charge are attracted to each other, forming ionic bonds. Chemical formulas for ionic compounds represent the proportion of ion of each element in the ionic array.

Targets:• Describe the ionic bond as the electrostatic attraction

between oppositely charged particles.• Describe how ions can be formed as a result of

electron transfer.• Predict whether a compound of two elements would

be ionic from the position of the elements in the periodic table or from their electronegativity values.

Chap 15 & 16: Chemical Bonding

Only one group of elements is stable (nonreactive). What is unique about their electron structure?

Filled s & p sublevels

All other elements react in order to achieve this stable electron configuration.

Ionic Bond: Transfer of electrons; metal + nonmetal

Covalent Bond: Sharing of electrons; nonmetal + nonmetal

Do not Write this Slide ObserveDescribe how ions can be formed as a

result of electron transfer.

Ions are formed when atoms

gain or lose electrons

• Fluorine gains one electron to become the fluoride ion having a charge of -1

• Lithium loses one electron to become the lithium ion having a charge of +1

Do Not Write this slide, ObserveDescribe the ionic bond as the

electrostatic attraction between oppositely charged particles.

• The fluorine ion (fluoride) has a negative charge (F1-)

• The lithium ion has a positive charge (Li1+)

• The bond is formed due to the electrostatic attraction between the opposite charges (1- and 1+)

How Ions are Formed

Ions are formed when atoms gain or lose electrons

Reaction between Sodium and Chlorine

• Sodium configuration: 1s22s22p63s1 or

__ __ __ __ __ __1s 2s 2p 3s

• If Na loses one electron then it would end in 2s22p6 and be stable.

• Then sodium has 11 protons (11+), but only 10 electrons (10-) so it acquires a charge of 1+ and becomes the sodium ion, Na+. In order for it to lose an electron, something has to gain an electron

Describe how ions can be formed as a result of electron transfer.

Ions are formed when atoms gain or lose electrons

Reaction between Sodium and Chlorine

• Chlorine configuration: 1s22s22p63s23p5 or

__ __ __ __ __ __ __ __ __1s 2s 2p 3s 3p

• If Cl gains one electron then it would end in 3s23p6 and be stable.

• Then chlorine has 17 protons (17+), and 18 electrons (18-) so it acquires a charge of 1- and becomes the chloride ion, Cl-. It will gain the electron from the sodium.

Reaction between Sodium and Chlorine

• Since opposite charges attract, the Na+ and Cl- ions form an ionic bond.

• Structure: [Na]+ [ Cl ]-

• Name: Sodium chloride

• Formula: NaCl

Describe how ions can be formed as a result of electron transfer.

Ions are formed when atoms gain or lose electrons

Reaction between Magnesium and Chlorine

• Magnesium configuration: 1s22s22p63s2 or

__ __ __ __ __ __1s 2s 2p 3s

• If Mg loses two electrons then it would end in 2s22p6 and be stable.

• Then magnesium has 12 protons (12+), but only 10 electrons (10-) so it acquires a charge of 2+ and becomes the magnesium ion, Mg2+. In order for it to lose two electrons, something has to gain two electrons

Ions are formed when atoms gain or lose electrons

Reaction between Magnesium and Chlorine

• Chlorine configuration: 1s22s22p63s23p5 or

__ __ __ __ __ __ __ __ __1s 2s 2p 3s 3p

• If Cl gains one electron then it would end in 3s23p6 and be stable.

• Then chlorine has 17 protons (17+), and 18 electrons (18-) so it acquires a charge of 1- and becomes the chloride ion, Cl-.

• Since chlorine can only gain one electron and magnesium gives up two electrons, magnesium requires two chlorine atoms.

Example

Reaction between Magnesium and

Chlorine

• Since opposite charges attract, the Mg2+ and the 2 Cl- ions form an ionic bond.

• Structure: [Mg]2+ [ Cl ]-

2

• Name: Magnesium chloride

• Formula MgCl2

Describe how ions can be formed as a result of electron transfer.

Reaction between Potassium and Oxygen

Student Practice – 1) Write the electron configuration for Potassium and

Oxygen, 2) Write the charge for the loss or gain of electrons, 3) Write the

Diagram 4) Formula and 5) Name. Potassium configuration: 1s22s22p63s23p64s1

• Potassium will lose 1 electron and become the potassium ion K+.

Oxygen configuration: 1s22s22p4

• Oxygen will gain 2 electrons and become the oxide ion O2-.

Two potassiums are needed to combine with one oxygen.

Diagram: [ K ]+ [ O ]2- [ K ]+ or [ K ]2+ [ O ]2-

Formula: K2O Name: Potassium oxide

Reaction between Aluminum and BromineStudent Practice

Diagram the bonding between Al and Br,

write the formula, and give the name.

Describe how ions can be formed as a result of electron transfer.

Reaction between Aluminum and Bromine

Diagram the bonding between Al and Br,

write the formula, and give the name.

Diagram: [Al]3+ [ Br ]-

3

Formula: AlBr3

Name: Aluminum bromideGO TO WHITE BOARD PRACTICE FOR IONS

Describe how ions can be formed as a result of electron transfer.

Draw the transfer of electrons

• Draw the electron transfer between potassium and chorine.

– Demonstrate on board here.

• Pass out ionic practice II• Pass out polyatomic ion periodic

table - And discuss• Pass out Ionic Bonding HO

Metal + NonmetalIonic compounds are generally composed of

a metal combined with a nonmetal(s)Pass Out Electronegativity Chart

Ionic bonds have electronegativity differences greater than or equal to 1.8

Electronegativity Difference

Table 16.4 (pg. 462) gives electronegativity differences and bond types

Predict whether a compound of two elements would be ionic from the position of the elements

in the periodic table or from their electronegativity values.

Ion Activities

• Review polyatomic handout

• Ion Practice Handout

• Ion cut and paste activity

• White Board Practice

Do not write – Science Standards

Chap 16: Covalent BondingStandard:PS2E: Compounds are composed of two or more elements bonded together in a fixed

proportion by sharing electrons between atoms, forming Covalent bonds. Such compounds consist of well-defined molecules. Formulas of covalent compounds represent the types and number of atoms of each element in each molecule.

Target:• Describe the covalent bond as the electrostatic attraction

between a pair of electrons and positively charged nuclei• Describe how the covalent bond is formed as a result of

sharing electrons.• Predict whether a compound of two elements would be

covalent from the position of the elements in the periodic table or from their electronegativity values.

• Compare and explain the properties of substances resulting from different types of bonding.

Describe the covalent bond as the electrostatic attraction between a pair of electrons and positively charged nuclei

Covalent bonds occur between nonmetals since both want to gain

electrons. They share electrons to achieve a stable configuration

Electron Dot Diagrams Need 1 electron: H F Cl Br I

Need 2 electrons: O S Se Te

Need 3 electrons: N P As

Need 4 electrons: C SiGO to Types of Chemical bonds/covalent bond HO

Student Practice:Write the Lewis (electron dot)

structures for each atom.

Single covalent bondsSharing 1 pair of

electrons

1) H2

2) HCl

3) CCl4

GO to Covalent molecule practice (kits)

Double covalent bondsSharing 2 pair of electrons4) O2

Triple covalent bondsSharing 3 pair of electrons5) N2

Review of Characteristics of Covalent Bond (polar and Nonpolar)

• Both: Combine NM + NM• Both: Low melting points, usually gases

and liquids, soft solids at room temp.• Both: Do not conduct electricity• Both: Consist of separate molecules• Polar: Molecules have weak charges due

to unequal attraction for electrons.• ex. O-H, N-H, C-O, H-Cl, all soluble in

water

Review of Characteristics of Covalent Bond (polar and Nonpolar) (Cont)

• Nonpolar: Molecules have slight to no charges due to equal attraction of electrons. Not soluble in water but soluble in organic solvents, ex. Alcohol or petroleum.

• Ex. C-C bond, C-C-C-C-C

Characteristics of Ionic Bonds

• Metal and nonmetal

• High melting points, usually a solid.

• Conducts electricity when melted or dissolved in water.

• Well defined crystals

• Usually soluble in water.

Student Practice

• Covalent Molecule Work Sheet

• Covalent Bonding Kits