Ionic Bonds

Section 3

Ion•An atom or group of atoms that has become electrically charged.

•When an atom loses an electron, it loses a negative charge and becomes a positive ion.

•When an atom gains an electron, it gains a negative charge and becomes a negative ion.

Ionic Bonds•An attraction between two

oppositely charged ions.

Ionic Bonds•Compounds created are electrically neutral.•Charges of ions balance.

Ionic Bonds

Sodium and chlorineNaCl – ionic bondp. 61

Ionic Bonds

•Mg + Cl MgCl₂ •MgCl₂ is a nuetral ion• Identify charge (Use p. 60 figure 8):

–Mg–Cl

Ionic Bond Practice

• How many ions of magnesium and oxygen would you need to make an electrically neutral compound?– Mg– O

– What is the formula of the compound?

Ionic Bond Practice

• How many magnesium ions and iodine ions would you need to make an electrically neutral compound?– Mg– I

• What would be this compound’s formula?

Ionic Bond Practice

• How many phosphate ions and potassium ions would you need to make an electrically neutral compound?– Phosphate– Potassium

• What would be this compound’s formula?

Polyatomic Ions

• Many atoms• A group of atoms that react as one• Each polyatomic ion also carry either a

positive or negative charge– CO₃ (has an overall charge of -2)– This polyatomic ion functions as all ions. It is

attracted to ions that would have a overall charge to equal a +2. This would create a stable molecule.

Polyatomic Ions

• CO₃ + Ca CaCO₃

• Does this compound have a positive, negative or neutral charge?

Formulas for compounds

• Sodium fluoride

• Lithium oxide

Formulas for compounds

• Magnesium sulfide

• Boron chloride

Formulas for compounds

• Aluminum sulfide

• The metal scandium (Sc) has three valance electrons. What is the formula of the ionic compound formed when scandium reacts with iodine?

Naming Ionic Compounds• Name of positively charged ion

comes first, followed by the name of the negative ion.• If the negative ion is an element

– the end of the name changes to –ide.

Properties of Ionic Compounds

•Crystal Shape•High melting points• Electrical conductivity

Crystal Shape• Comes from the arrangement

of ions.• Ions are orderly and organized• Every ion is attracted to ions

near it that have an opposite charge.

High Melting Points

• Strong ionic bonds – difficult to break• When enough heat is applied – atoms speed

up. When they achieve enough energy the ions will overcome the attraction of the ionic bond and break free and change state.

• Table salt requires 801⁰C to melt.• This causes ionic compounds to be solids at

room temperature.

Electrical Conductivity• When dissolve in water, the solution conducts

electricity (the flow of electrons)• A solid ionic compound does not conduct

electricity• In a solid ionic compound – particles are in a fixed

position – electricity does not flow• When ions dissolve in water – ions move freely

and electrons will flow freely.• Melting ionic compounds allows electricity flow