chapter four chemical bonding: the ionic bond model

Chapter FourChapter FourChemical Bonding:

The Ionic Bond Model

Chapter 4 | Slide 2

Chemical Bonding: The Ionic Bond Model cont’d

Chemical Compounds• _________ Compounds

– Usually Metal and Nonmetal ions– ________ Bonds– Solids, high melting, conducts electricity (molten or in

solution)

• __________ Compounds– Usually between Atoms of same Element or between

atoms of nonmetals– __________ Bonds– Gases, liquids, or low melting solids, non-conductor

Chapter 4 | Slide 3

Chemical Bonding: The Ionic Bond Model cont’d

• What are chemical bonds?• Chemical bond: attractive _______ holding two or

more atoms together.• Ionic bond results from the attraction of ________

and ____________ ions– Usually, a metal forms the ________ ion and a

nonmetal forms the _________ ion

• Covalent bond results from _________ electrons between the atoms. – Usually found between ____________

Chapter 4 | Slide 4

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 Focus is on Ionic Bonds• Bond formed through the ________ of one or

more electrons from one atom or group of atoms to another atom or group of atoms

• Metals tend to give up electrons and form ______• Non-metals tend to accept electrons and form

_________• The Ionic Bond is formed by the attraction

between the _____ and ____ charges

Chapter 4 | Slide 5

Chemical Bonding: The Ionic Bond Model cont’d

Recall Chapter 3 Topic Electron Configurations

Electrons residing in outer most energy level are called distinguishing or valence electrons

Valence electrons determine chemical properties or how atoms of one particular element interact (give up or gain electrons) with atoms of another element

Chapter 4 | Slide 6

Chemical Bonding: The Ionic Bond Model cont’d

• Valence Electrons:– Example: Mg: ________________________– Example: Cl: ____________________________

• An easy way to determine how many valence electrons an element has:– The number of valence electrons is _______ to the

group number (for elements in the s and p blocks)

Chapter 4 | Slide 7

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 8

Chapter 4 | Slide 9

Chemical Bonding: The Ionic Bond Model cont’d

How many valence electrons do the following elements have?– Na

– Al

– S

– Cl

Chapter 4 | Slide 10

Chemical Bonding: The Ionic Bond Model cont’d

Lewis SymbolIs the chemical symbol of an element surrounded by dots equal in

number to the number of __________ electrons present in atoms of the element

Elements in the same group have the same number of ___________ electrons

The number of __________ electrons for elements in the same group is the same as the “A” Group number

The maximum number of ____________ electrons for any element is eight (H and He exceptions)

Eight ____________ electrons is most stable and results in the rule of eight or octet rule to produce a noble gas electron configuration

Chapter 4 | Slide 11

Chemical Bonding: The Ionic Bond Model cont’d

→ Fig. 4.2 Gilbert Newton Lewis was one of the foremost chemists of the 20th century.

Edgar Fahs Smith Collection, University of Pennsylvania Library

Chapter 4 | Slide 12

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 13

← Fig. 4.3 Loss of an electron from a sodium atom leaves it with one more proton than electrons, so it has a net electrical charge of +1.

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 14

Chemical Bonding: The Ionic Bond Model cont’d

Fig. 4.4 a-c (a,b) Two-dimensional cross section and a three-dimensional view of sodium chloride. (c) sodium chloride crystals

Chapter 4 | Slide 15

Focus on Mg and Cl

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 16

Chemical Bonding: The Ionic Bond Model cont’d

Let’s look at Mg. Its electron configuration is 1s22s22p63s2.– If it loses ____ electrons to become ________, it will

have the electron configuration 1s22s22p6

• ____ Valence Electrons!– If it gains ____ electrons to become ______, it will have

the electron configuration 1s22s22p63s23p6

• ___ Valence Electrons!– The question is which is easier? To lose TWO electrons

or to gain SIX?• Losing two: Therefore, Mg tends to form Mg2+ ions

Chapter 4 | Slide 17

Chemical Bonding: The Ionic Bond Model cont’d

Let’s look at Cl. Its electron configuration is 1s22s22p63s23p5.– If it loses ____ electrons to become ______, it will

have the electron configuration 1s22s22p6

• ___ Valence Electrons!– If it gains _____ electron to become ______, it will

have the electron configuration 1s22s22p63s23p6

• ___ Valence Electrons!– The question is which is easier? To lose SEVEN

electrons or to gain ONE?• Losing ONE: Therefore, Cl tends to form Cl- ions

Chapter 4 | Slide 18

Chemical Bonding: The Ionic Bond Model cont’d

• So, Mg will form Mg2+ ions, and Cl will form Cl- ions.

• Opposite charges attract:

• Mg2+ + 2Cl- MgCl2

Chapter 4 | Slide 19

Chemical Bonding: The Ionic Bond Model cont’d

Isoelectronic SpeciesAre atoms or ions that have the ______ number

and configuration of electrons.

N3- O2- F1- Na1+ Mg2+ Al3+

All are isoelectronic with ______ and all have the electronic configuration 1s2 2s2 2p6

Chapter 4 | Slide 20

Chemical Bonding: The Ionic Bond Model cont’d

Formula Units

The smallest whole number repeating ratio of ions present in an ionic compound that results in charge neutrality.

NaCl MgCl2 AlCl3

Na2O MgO Al2O3

Chapter 4 | Slide 21

→ Fig. 4.5 Cross section of the structure of the ionic solid NaCl.

Chemical Bonding: The Ionic Bond Model cont’d

E. R. Degginger/Color-Pic

Chapter 4 | Slide 22

Chemical Bonding: The Ionic Bond Model cont’d

• The number of electrons an atom loses or gains is related to its position on the periodic table.

Chapter 4 | Slide 23

Chemical Bonding: The Ionic Bond Model cont’d

• Group IA metals • Group IIA metals • Group IIIA metals • Group VIIA nonmetals • Group VIA nonmetals • Group VA nonmetals

Chapter 4 | Slide 24

Chemical Bonding: The Ionic Bond Model cont’d

→ Fig. 4.8 Periodic table in which the metallic elements that exhibit a fixed ionic charge are highlighted.

Chapter 4 | Slide 25

Chemical Bonding: The Ionic Bond Model cont’d

Writing Formulas for compounds• For compounds, a neutral species, the number of

electrons lost and gained must be _______.• The amount of positive charge must _______ the

amount of negative charge.• Formulas of ionic compounds

– Symbol for the positive ion is always written first– The charges on the ions are _______ shown in the

formula– The _____________ in the formula give the combining

ratio for the ions

Chapter 4 | Slide 26

Chemical Bonding: The Ionic Bond Model cont’d

It may be helpful to initially write in the charges of each ion, then determine the number of + and – ions that would balance out the charges.

K1+ S2-

Al3+ O2-

Chapter 4 | Slide 27

Chemical Bonding: The Ionic Bond Model cont’d

Naming Ionic Compounds• First word of name:

– Name of ___________ (first element in formula)– If the metal can form more than one _________, then

the charge is indicated in parentheses in the name. • Examples: Cu+ = copper (I); Cu2+ = copper (II).

• Second word of name:– Name of ________ (second element in formula). Write

the _____ of the name of the nonmetal ion with the –ide ending

Chapter 4 | Slide 28

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 29

Chemical Bonding: The Ionic Bond Model cont’d

What is the name or formula for each of the following?

• K3N

• AuCl3

• PbS

Chapter 4 | Slide 30

• Chromium (III) oxide

• Iron (II) oxide

• Magnesium Chloride

Chapter 4 | Slide 31

Chemical Bonding: The Ionic Bond Model cont’d

Thus far these have been compounds formed by Metal Cations and Non-metal Anions.

An ionic compound in which one element present is a metal and the other element present is a nonmetal is called a “_________ Ionic Compound”

Chapter 4 | Slide 32

Chemical Bonding: The Ionic Bond Model cont’d

• Monatomic ion– An ion formed from a _______ atom through loss or

gain of electrons– Examples: Na+, S2-, etc.

• Polyatomic ion– An ion formed from a ______ of atoms (held together by

covalent bonds) and as a whole becomes charged through loss or gain of electrons

– Can be the positive or the negative ion in an ionic compound

Chapter 4 | Slide 33

Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 34

Chemical Bonding: The Ionic Bond Model cont’d

• Give the formulas and names of the ionic compounds formed between the following ions:

– NH4+ & PO4

3-

– Na+ & NO31-

– NH4+ and O2-

Chapter 4 | Slide 35

– NH4+ and PO4

3-

– Li+ and CO32-

– Mg2+ and NO31-

Chapter 4 | Slide 36

Chemical Bonding: The Ionic Bond Model cont’d