Chapter 15Chapter 15Ionic Bonding and CompoundsIonic Bonding and Compounds

The properties and chemical reactivity of The properties and chemical reactivity of all compounds is based on how they are all compounds is based on how they are bonded together.bonded together.

In this unit we will look at Ionic, Covalent In this unit we will look at Ionic, Covalent and Metallic bondsand Metallic bonds

Ionic compounds are compounds formed Ionic compounds are compounds formed by atoms giving up or receiving electrons.by atoms giving up or receiving electrons.

Ionic compounds (p.422)Ionic compounds (p.422)

Fluoride compoundMicroscopic view of an ionic compound

dDwtMjA3

Sodium Chloride

Limestone: Calcium carbonate

Review electron configuration and Review electron configuration and Valence Electrons (p.412-414)Valence Electrons (p.412-414)

NaNa1s1s22 2s 2s22 2p 2p66 3s 3s11

SS 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p44

ClCl1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p55

Notice that the number of Notice that the number of valence electronsvalence electrons (the (the electrons in the outer most energy levels) electrons in the outer most energy levels) correspond with their ‘family/group’correspond with their ‘family/group’

Add this to your periodic tablesAdd this to your periodic tables

Electron Dot Diagrams (p. 414)Electron Dot Diagrams (p. 414)

Structures that show the element and how Structures that show the element and how many valence electrons it hasmany valence electrons it has

See Table 15.1See Table 15.1 This will be helpful when determining how This will be helpful when determining how

many elements are required for chemical many elements are required for chemical bondingbonding

The Duet and Octet Rule The Duet and Octet Rule (p. 414-415)(p. 414-415)

Remember that most atoms Remember that most atoms (representative elements) want to obtain (representative elements) want to obtain the electron configurations of a noble gas; the electron configurations of a noble gas; they want their outer most energy level they want their outer most energy level filledfilled

This is called the duet (if the atom is closer This is called the duet (if the atom is closer to helium, such as Lithium) or octet rule to helium, such as Lithium) or octet rule (for the rest of the noble gases)(for the rest of the noble gases)

1s1s22 for the duet or ns for the duet or ns22 np6 for the octet np6 for the octet

Electron Configuration for Cations Electron Configuration for Cations (p. 414-416)(p. 414-416)

Remember that Cations are atoms that have Remember that Cations are atoms that have LOST electrons. They are positively chargedLOST electrons. They are positively charged

Look at the Lewis Dot Diagrams for Na and MgLook at the Lewis Dot Diagrams for Na and Mg It is easier for them to LOSE their outer most It is easier for them to LOSE their outer most

electrons, so the will form cations and obtain the electrons, so the will form cations and obtain the electron configuration of Neon electron configuration of Neon

Their outer most electrons are in the 3sTheir outer most electrons are in the 3s22 and 3p and 3p66 They have obeyed the ‘octet’ ruleThey have obeyed the ‘octet’ rule

Electron Configuration for Anions Electron Configuration for Anions (p. 417-418)(p. 417-418)

Remember that Anions are atoms that have Remember that Anions are atoms that have GAINED electrons. They are negatively GAINED electrons. They are negatively charged.charged.

Look at the Lewis Dot Diagrams for O and F.Look at the Lewis Dot Diagrams for O and F. It is easier for them to GAIN electrons in their It is easier for them to GAIN electrons in their

outer most shells, so the will form anions and outer most shells, so the will form anions and also obtain the electron configuration of Neon also obtain the electron configuration of Neon

Their outer most electrons are in the 3sTheir outer most electrons are in the 3s22 and 3p and 3p66

They have obeyed the ‘octet’ ruleThey have obeyed the ‘octet’ rule

Ionic Bonds (p. 419-421)Ionic Bonds (p. 419-421)

Ionic bonds are compounds formed between Ionic bonds are compounds formed between cations and anionscations and anions

How would you write the formula potassium How would you write the formula potassium chloride? chloride? KCl (a ratio of 1:1)KCl (a ratio of 1:1)

Now go back and write the Lewis Dot Diagrams Now go back and write the Lewis Dot Diagrams for each.for each.

Notice that K is needing to give up one electron Notice that K is needing to give up one electron and Cl is wanted to gain one electronand Cl is wanted to gain one electron

Hence the ratio of 1:1Hence the ratio of 1:1

Practice writing the following:Practice writing the following:Calcium OxideCalcium Oxide

Barium NitrideBarium Nitride

Cesium OxideCesium Oxide

Homework:Homework:

p. 418 #1,2,3,4,6; p. 425 #9, 10, 11, p. 418 #1,2,3,4,6; p. 425 #9, 10, 11, 12abc, 13; p. 432 #20, 23, 24, 26, 30, 33, 12abc, 13; p. 432 #20, 23, 24, 26, 30, 33, 3737

Take your Chemistry book and binder to Take your Chemistry book and binder to lab this weeklab this week