Chapter 15Chemical Compounds

•Ionic compounds have ionic bonds between opposite charges (ions).•Covalent compounds have covalent bonds (sharing electrons)and consist of particles called molecules.

PropertyIonic

compoundsCovalent

compounds

Brittleness

Melting point

Solubility in H2O

Electrical conductivity

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point

Solubility in H2O

Electrical conductivity

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point

Solubility in H2O

Electrical conductivity

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point

Solubility in H2O

High solubility

Electrical conductivity

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point

Solubility in H2O

High solubility

Electrical conductivity Good conductors

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point Low melting point

Solubility in H2O

High solubility

Electrical conductivity Good conductors

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point Low melting point

Solubility in H2O

High solubility Low solubility

Electrical conductivity Good conductors

PropertyIonic

compoundsCovalent

compounds

Brittleness Very brittle

Melting point High melting point Low melting point

Solubility in H2O

High solubility Low solubility

Electrical conductivity Good conductors Poor conductors

Properties of Acids:

• Produce hydrogen ions (H+) in water.– The H+ ion makes hydronium ion (H30+) with a

water molecule.

• Taste sour.• React with metals and carbonates (CO3).• Turns blue litmus paper red.– Litmus paper is paper treated with an indicator.

An indicator is a compound that changes color when in contact with an acid or a base.• Examples:–Litmus paper (red litmus paper, blue

litmus paper, pH paper)–Phenol red solution–Red cabbage juice

Strength of acids:• Not based just on concentrations!

Strong acids Weak acids

Strength of acids:• Not based just on concentrations!

Strong acids Weak acids

All molecules break apart into

ions(or “dissociate”)

Strength of acids:• Not based just on concentrations!

Strong acids Weak acids

All molecules break apart into

ions(or “dissociate”)

Few molecules break apart

Examples of acids:

Strong acids• hydrochloric

HCl• sulfuric

H2SO4

• nitric

Weak acids• acetic (in vinegar)• citric (citrus fruits)• carbonic

Properties of a Base:

• Make Hydroxide ions (OH-) in water.• Taste bitter.• Feels slippery.• Does not react with carbonates.• Turns red litmus paper blue.–Think “b” base turns blue

Strength of a base:NaOH Na+ + OH-

Strong base Weak base

Strength of a base:NaOH Na+ + OH-

Strong base Weak base

All molecules break apart into ions

(or “dissociate”)

Strength of a base:NaOH Na+ + OH-

Strong base Weak base

All molecules break apart into ions

(or “dissociate”)

Few molecules break apart

Examples of bases:Strong bases• Sodium hydroxide

NaOH• Calcium hydroxide

CaOH• Potassium hydroxide

KOH

Weak bases• Ammonium hydroxide• Aluminum hydroxide

The pH scale

• Ranges from 0 to 14 (see pg 429)

• Expresses the concentration of hydrogen (H+) ions in a solution;

• Low pH means high concentration of H+ (strong acid);

• High pH means low concentration of H+ (strong base or alkaline)

pH values for common household chemicals

pH scale

Where are the strong acids?

pH values for common household chemicals

Where are the strong acids?

pH is important to living organisms!

Where are the strong acids?

pH Scale and Indicatorsvideo:

A neutralization reaction is between an acid and a base, and always produces water and a salt. HCl + KOH H2O + KCl

hydrochloric potassium water potassium acid hydroxide chloride

(a salt!)

A salt is an ionic compound (like Na+Cl-).