IONIC BONDINGChemistry 11

Resource: Chang’s Chemistry Chapter 9

Activities Quizzes Exercises Molecular geometry models Lab: Comparing ionic and covalent

compounds Lab: Boiling points

Objectives Describe the ionic bond as the electrostatic attraction

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

transfer. Deduce which ions will be formed by elements in groups

1, 2, 3, 5, 6, and 7. State that transition elements can form more than one ion. 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.

State the formula of common polyatomic ions formed by nonmetals in periods 2 and 3.

Describe the lattice structure of ionic compounds.

Lewis dot symbols The discovery of the periodic table and

electron configuration gave rise to an even greater understanding of chemistry—bonding.

Lewis stated that:Atoms combine to achieve greater stabilityMaximum stability is achieved when the electron

configuration resembles that of a noble gas. What properties of noble gases support

this?

Lewis dot symbols A Lewis dot symbol is a representation of

an element. It consists of:

The symbol of the elementOne dot for every valence electron in an atom of

the element. What other representations of elements

have we used so far?

Lewis dot symbolsLewis dot symbol of

Lewis dot symbolsDraw the Lewis dot symbol for:

hydrogensodium

What do you notice?

Draw the Lewis dot symbol for:carbonoxygen

Ion formation Recall the definition of an ion and the two

types of ions. Why do atoms form ions? What roles do you think ionization energy

and electronegativity play in the formation of ions?

Factor Cation or Anion?High ionization energyHigh electronegativity

Ion formation Explain why atoms form ions using

Lewis’s ideas.

Factors that affect the formation of ionsFactor Cation or Anion?

high ionization energy anionlow ionization energy cationhigh electronegativity anionlow electronegativity cation

Ion formationPredict and explain the ion formation of the

following elements:lithiumsodiumberylliummagnesiumaluminumoxygenfluorine

Ion formation As a rule:

the alkali metals (Group I) and alkaline earth metals (Group II) form cations, and

the halogens and oxygen form anions

With this in mind, how do you think ionic bonds are formed?

The ionic bond An ionic bond is the electrostatic force

that holds ions together in an ionic compound.

Consider the compound lithium fluoride.Macroscopically, it is a poisonous white

powder used in manufacturing.Use your knowledge of electron

configuration to describe lithium fluoride at the atomic / molecular level.

The ionic bondThe electron configurations of lithium and

fluoride are:Li 1s22s1

F 1s22s22p5

Lithium surrenders its 2s1 valence electron to fluorine and thus, both achieve the electron configuration of a noble gas.

The ionic bondWrite the electron configurations of Li and F

when they are in an ionic compound.Which noble gases’ configurations do they resemble?

The process can also be represented using Lewis dot symbols (p 247)Notice the steps involved in the formation of the ionic bond between Li and F.

Ionic compounds What holds ionic compounds together? The ions involved in ionic compounds

are electrically charged. Can we then assume that ionic compounds are also charged?

Ionic compounds Ionic compounds are held together by

the electrostatic force between charged ions, but

Ionic compounds themselves are electrically neutral.

Lattice structure Consider a very common ionic

compound, NaCl (rock salt). What is its gross appearance?

The transition metals The transition metals are known to

commonly form more than one ion. This comes from the existence of the 3d

subshell. Ions of transition metals are commonly

of the +2 and +3 charges. Which subshell are the electrons of

transition metals taken from?

Polyatomic ions It is not uncommon for two nonmetals to

join to form a polyatomic ion. Can you predict the charge of the

following polyatomic ions?hydroxide (OH)ammonium (NH4)

Polyatomic ions One of the elements will be considered as

“positive” and the other will be considered “negative”.

Some common polyatomic ions Name Molecular formula Charge

hydroxide OHnitrate NO3

sulfate SO3

cyanide CNcarbonate CO3

ammonium NH4

Objectives Describe the ionic bond as the electrostatic attraction

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

transfer. Deduce which ions will be formed by elements in groups

1, 2, 3, 5, 6, and 7. State that transition elements can form more than one ion. 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.

State the formula of common polyatomic ions formed by nonmetals in periods 2 and 3.

Describe the lattice structure of ionic compounds.

ExercisesChang’s Chemistry

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