Chemistry is a Physical Science

Chapter 1, Sections 1 and 2

Introduction Chemistry: the study of the composition,

structure and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes

There are six branches of chemistry to deal with the main areas of study

The branches often overlap

Matter

Mass: a measure of the amount of matter Matter: anything that occupies space

(has volume) and has mass

Basic Building Blocks of Matter

• Atom: the smallest unit of an element that maintains the chemical identity of that element

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

More Building Blocks

Compound: a pure substance that can be broken down into simple stable substances

Each compound is made from the atoms of two or more elements that are chemically bonded

Molecule: smallest unit of an element or compound that retains all the properties of that element or compound (for now)

Types of Properties

• Extensive properties: depend on the amount of matter that is present

Examples include: volume, mass, amount of energy in a substance

• Intensive properties: do not depend on

the amount of matter present

Examples include: melting and boiling point, density, ability to conduct electricity and

transfer heat

Properties Physical properties: properties that can be

observed and measured without changing the material's composition

• Examples would be color, density, melting point, boiling point

Chemical properties: properties that can only be observed by changing the composition of the material

• Examples: reactivity, ability to burn, acidity, decompose

Changes

Chemical change: changes the chemical properties of the substance, you will have new substance(s) with new properties

A chemical change is the result of a chemical reaction

Physical change: does not change the chemical properties of the substance, usually changes its state of matter

Changes

• Reactants: the substances that react in a chemical change

• Products: the substances that are formed by the chemical change

States of Matter

• Solid: has a definite volume and definite shape

• Liquid: has a definite volume but an indefinite shape (assumes the shape of the container)

• Gas: no definite volume or shape (assumes the shape of the entire container)

• Plasma: high-temperature physical state of matter in which atoms lose most of their electrons

Mixture

Different substances not combined chemically

Can be separated by physical means Ratio of the components is not constant Its properties are similar to those of its

components

Types of Mixtures

• Homogeneous mixture

• uniform in composition

• AKA solution

• Heterogeneous mixture

• Not uniform throughout

• Can usually see the different components

To Separate a Mixture

Pick out the big pieces

Filtration, decant,

centrifuge Paper

chromatography Distillation Use of a magnet

Pure Substances

Can only be separated by chemical means All samples have identical chemical

properties with the same composition Are further divided into elements and

compounds Elements can not be split up into simpler

substances by chemical means, compounds can

HON and the Halogens

Hydrogen (H), oxygen (O), nitrogen (N), and the halogens (fluorine, chlorine, bromine, and iodine) are diatomic in all physical states