Drill

Determine the name of the following:

1. NaOH

2. HCl

Objective

The student will be able to: Define the laws of definite and

multiple proportions in order to name chemical compounds.

SAT/HSA Enrichment

The formula H2 represents one …

a. Mole

b. Atom

c. Liter

d. Molecule

e. Gram

The Laws Governing Formulas and Names

The Laws Governing Formulas and Names

• A birthday cake for a four-year-old has four candles. The ratio of candles to birthday cake is 4:1. In chemistry, similar relationships exist among the masses of elements as they combine in compounds.

The rules for naming and writing formulas for compounds are possible only because compounds form from the elements in predictable ways.These ways are summed up in two laws:

the law of definite proportions and the law of multiple proportions.

The Laws of Definite and Multiple Proportions

The Law of Definite ProportionsThe law of definite proportions

states that in samples of any chemical compound, the masses of the elements are always in the same proportions.

The Laws of Definite and Multiple Proportions

Water obeys the law of definite proportions. In every sample of water, the mass ratio of oxygen to hydrogen is always 8:1.

The Laws of Definite and Multiple Proportions

Hydrogen peroxide obeys the law of definite proportions. The mass ratio of oxygen to hydrogen is always 16:1.

The Laws of Definite and Multiple Proportions

The Law of Multiple ProportionsThe law of multiple proportions:

Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.

The Laws of Definite and Multiple Proportions

•A Diagram of the Law of Multiple Proportions

The Laws of Definite and Multiple Proportions

Conceptual Problem

Conceptual Problem

Conceptual Problem

Follow the arrows and answer the questions on the flowchart to write the correct name for a compound.

Practicing Skills: Naming Chemical Compounds

Practicing Skills: Naming Chemical Compounds

CuSO4 is an example from the flowchart. The compound will end in -ite or -ate. Cu is not part of Group A, so you must name the ions and use a Roman numeral to identify the charge of the transition metal. The name is copper(II) sulfate.

Practicing Skills: Naming Chemical Compounds

In writing a chemical formula from a chemical name, it is helpful to remember the following guidelines.An -ide ending generally indicates a

binary compound.An -ite or -ate ending means a

polyatomic ion that includes oxygen is in the formula.

Practicing Skills: Naming Chemical Compounds

Prefixes in a name generally indicate that the compound is molecular. A Roman numeral after the name of a

cation shows the ionic charge of the cation.

Practicing Skills: Naming Chemical Compounds

Practicing Skills: Naming Chemical Compounds

Section Quiz

1.The law of definite proportions states that in samples of any chemical compound, the elements are always in the same proportion by

a.mass.b.volume.c.group number.d.period number.

Section Quiz

2.You want to write the chemical formula for iron(II) chloride. Based on Figure 9.22, after identifying symbols, what is the correct next step in the flowchart?

a.Group A elementsb.Roman numeralsc.Balance chargesd.Polyatomic ions

Section Quiz

3.Using the flowchart in Figure 9.20, if you determine that the name of an ion ends in -ite or -ate, the ion is a

a.polyatomic cation.b.polyatomic anion.c.transition metal cation.d.group A anion.

Guided Reading

Students will complete guided reading 9.5 and guided practice problems 2, 10B and 10C, 13B and 34.

Summary Questions

Did we accomplish the objective? Explain.

Define Law of Definite Proportions.

Define Law of Multiple Proportions.

Do you have any questions about the unit?

Homework

Study for your Exam next class Complete any Make-up work that

you may have.

Exit ticket: Law Governing Formulas and

Names