CHAPTER 1: MATTER AND CHANGEChemistry 1-2

Mr. Chumbley

SECTION 1: CHEMISTRY IS A PHYSICAL SCIENCE

WHAT IS CHEMISTRY?

For most of human history, the natural sciences were divided into two broad categories: Biological Sciences Physical Sciences

However, those divisions began to break down as knowledge increased

Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes

BRANCHES OF CHEMISTRY

As the understanding of matter and its processes increased, different branches of chemistry arose to better describe specific types of chemicals and processes

A chemical is any substance that has a definite composition

Organic Chemistry Inorganic Chemistry

Physical Chemistry Analytical Chemistry

Biochemistry Theoretical Chemistry

CHEMISTRY APPLICATIONS

Basic chemical research is conducted for the purpose of expanding knowledge

Applied chemical research is conducted for the purpose of solving a specific problem

Technological development involves the production and use of products to improve the quality of life

HOMEWORK

Read: Chapter 1, Sections 2: Matter and Its Properties Stop once you get to “Main Idea: Matter can be a

pure substance or a mixture.”

SECTION 2: MATTER AND ITS PROPERTIES

WHAT IS MATTER? It is much easier to identify that things are made up

of matter than it is to define matter

By looking at the same properties for all matter there are two universal commonalities: Things made of matter take up space (have volume) Things made of matter have mass

Mass is a measure of the amount of matter

Using these universal characteristics we can define matter

Matter is anything that has mass and takes up space

ATOMS ARE THE BUILDING BLOCKS OF MATTER

While matter exists in many different forms, the most fundamental form is the atom

An atom is the smallest unit of an element that maintains the chemical identity of that element

An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom

ATOMS ARE THE BUILDING BLOCKS OF MATTER

When atoms of different elements chemically combine, molecules of a compound are formed

A compound is a substance that can be broken down into simple stable substances, but is made from the atoms of two or more elements that are chemically bonded

The smallest unit of a compound is a molecule

ALL SUBSTANCES HAVE CHARACTERISTIC PROPERTIES The specific characteristics of a substance, either element or

compound, are considered its properties

Properties can be used to identify individual substances, or an entire group of substances

Properties can be one of two types

Extensive properties depend on the amount of matter present mass volume total energy

Intensive properties do not depend on the amount of matter present melting point boiling point density conductivity

PHYSICAL PROPERTIES

Properties of substances are often used as identifying characteristics

Physical properties are characteristics that can be observed or measured without changing the identity of the substance

Examples:mass color shape

density volume texture

boiling point melting point conductivity

PHYSICAL CHANGES

The physical properties of a substance are can change, even if the substance does not

A physical change is a change in a substance that does not involve a change in the identity of the substance

Examples:cutting grinding polishing

boiling melting dissolving

STATES OF MATTER

Matter exists in states of matter that are physical properties

When a substance undergoes a change of state, it is a physical change from one state to another

While the substance has some new and different physical properties, the chemical identity has not changed

STATES OF MATTER

State of Matter

Definite Shape

Definite Volume

Solid Yes Yes

Liquid No Yes

Gas No No

As a substance changes from solid to liquid to gas, the atoms or molecules become less organized and have increasing ability to move away from each other

A fourth state of matter, plasma, is a high-temperature physical state of matter in which atoms lose most of their electrons

CHEMICAL PROPERTIES

In any situation where a substance could change its identity, chemical properties can be observed

Chemical properties relate to a substances ability to undergo changes that transform it into a different substance

Examples:reactivity chemical

stability flammability

toxicity combustibility radioactivity

CHEMICAL CHANGES

A chemical change (or chemical reaction) is a change in which one or more substances are converted into different substances

The reactants are the substances that react in a chemical change

The products are the substances that are formed by the chemical change

SIGNS OF A CHEMICAL CHANGE

Production of an odor

Change in temperature

Change in color

Formation of bubbles

Formation of a solid

Emission of light

ENERGY AND CHANGES IN MATTER

In both physical and chemical changes, energy is involved

Many different types of energy can be involved

The law of conservation of energy says that energy can be absorbed or released, but it is never created nor destroyed

HOMEWORK

Read: Chapter 1, Sections 2: Matter and Its Properties Start at “Main Idea: Matter can be a pure

substance or a mixture.” Finish at the end of Section 2 Answer #1-5 of the Formative Assessment on p.

14

MATTER CAN BE A PURE SUBSTANCE OR A MIXTURE

The variety of forms in which matter can exist is enormous

Two major classifications of matter are whether or not it is a pure substance or a mixture

Regardless of whether a sample is a pure substance or a mixture, it can be described and classified in terms of its properties

PURE SUBSTANCES

A pure substance is any form of matter that has a fixed, or definite, composition

Pure substances have two defining characteristics:

Every sample of a given pure substance has exactly the same characteristic properties.

Every sample of a pure substance has exactly the same composition.

MIXTURES

A mixture is a blend of two or more kinds of matter each of which retains its own identity and properties

Another way of describing a mixture is that the matter combines physically, but not chemically

Since mixtures do not have a defined composition, the amount of different substances within a sample of a mixture must be specified

MIXTURES

Mixtures can be described by the uniformity of their compostion

Homogeneous mixtures (or solutions) are mixtures that are uniform in composition

Heterogeneous mixtures are mixtures that are not uniform in composition

MIXTURES

One of the most important characteristics of a mixture is that it can be physically separated

Examples of physical separation: Filtration Vaporization Settling Centrifuge separation Chromatography

LABORATORY CHEMICALS AND PURITY

Typically, we treat chemicals used in the laboratory is if they were pure

Chemicals do have impurity, and depending on the standards and grade desired or used

The level of purity is important to know since the level of impurities can affect results