ch11 lecture outline

Chapter 11: Investigating Matter

Principles of Science

This lecture will help you understand:

• Chemistry: The Central Science• The Submicroscopic World• The Phases of Matter• Physical and Chemical Properties• Determining Physical and Chemical Changes• Elements to Compounds• Naming Compounds

Chemistry: The Central Science

Chemistry is the study of matter and the transformations it can undergo.

Physics Biology

AstronomyEarth Science


Chemistry


• Chemistry is a "materials" science.– Most of the material items in any modern

house are shaped by some human-devised chemical process.


• More than 70% of all legislation placed before the U.S. Congress addresses science-related questions and issues.

The Submicroscopic World

• Roughly 250,000 dunes of this size contain about 125 million trillion grains of sand.

• Yet, that's how many atoms there are in a single grain of sand. (Atoms are small.)

What are atoms?

• Atoms are the smallest particles of matter • Atoms make up everything around us • Molecules are combinations of atoms • Elements are only one type of atom • Compounds are made up of different types of

atoms

The Phases of Matter

• One of the most evident ways we can describe matter is by its physical form, which may be one of three phases (also sometimes described as physical states):

• The gaseous phase of any material occupies significantly more volume than either its solid or liquid phase.

• Frozen carbon dioxide, CO2, "dry ice"


GasGas

LiquidLiquidSolidSolid

DepositionDepositionSublimationSublimation

MeltingMelting

FreezingFreezing

CondensationCondensationEvaporationEvaporation


Physical and Chemical Properties

• A physical property describes the look or feel of a substance.


• A chemical property describes the tendency of a substance to transform into a new substance.

It is a chemical property of iron to transform into rust.



A physical change is a change in the physical properties of a substance.

• Chemical properties are properties that characterize the ability of a substance to react with other substances or to transform from one substance into another.


• Any change in a substance that involves a rearrangement of the way atoms are bonded is called a chemical change.

Determining Physical and Chemical Changes

CarbondioxideCarbondioxideOxygenOxygen CarbonCarbon



• A physical change is a change in the physical properties of a substance.

• A chemical change is the transformation of one or more substances into others.– A substance is identified not only by the kinds

of atoms it contains but also by how those atoms are connected to one another.

– During a chemical change, a new substance is formed as atoms rearrange themselves into new configurations.


• A physical change imposes a new set of conditions on the same material.

• A chemical change forms a new material that has its own unique set of physical properties.

• Both physical and chemical changes result in a change in physical appearance.

Potassiumchromate

Potassium chromate + Heat Potassiumchromate(cooled)


• Physical or chemical change?

Physical or chemical change?

Ammoniumdichromate

Ammonium dichromate + Heat Ammonia,water,chromium(III) oxide

• An element is a material made of only one kind of atom. Pure gold is an element because it is made of only gold atoms.

• An atom is the fundamental unit of an element.

• The term "element" is used when referring to macroscopic quantities.

• The term "atom" is used when discussing the submicroscopic.

Elements to Compounds

Compound Formula

Oxygen O2

Ozone O3

Sulfur S8

Gold Au


• The elemental formula is used to show the proportion by which atoms combine to form an element.


A compound is a substancethat consists of atoms ofdifferent elements.


• Compounds have properties uniquely different from the elements from which they are made.

Compound Formula

Sodium chloride NaCl

Ammonia NH3

Water H2O


• A chemical formula is used to show the proportion by which elements combine to form a compound.

• Guideline 1– Start with the element farthest to the left in the

periodic table.– For the element to the right, add the suffix -ide.

Example:

NaCl

Naming Compounds

Sodium chloride

Example:

NaCl

Na Cl

Naming Compounds

Naming Compounds

• Guideline 2– With different possible combinations of

elements, use prefixes to remove ambiguity.

mono-

di-

tri-

tetra-

1

2

3

4

Naming Compounds

Examples:

CO carbon monoxide

CO2 carbon dioxide

Naming Compounds

Examples:

H2O dihydrogen monoxide

H2O2 dihydrogen dioxide

Naming Compounds

Examples:

H2O water

H2O2 hydrogen peroxide

Naming Compounds

Naming Compounds

• Guideline 3– Common names are sometimes used for

convenience.

ch11 lecture outline

Science

physical change

chemical properties

physical property

phases of matter physical

physical states

physical form

chemical change forms

chemical process