CHAPTER 1- INTRODUCTION TO MATTER

MATTER The “stuff” that makes up everything in the universe. It has a variety of properties (characteristics) These characteristics can be used to identify substances.

Each specific substance has its own combination of properties that can be used to identify it. Chemistry is the study of matter and how matter changes

Elements The building blocks of matter, all matter is composed of elements

Elements are made of atoms. Atoms are the building blocks of elements.

How many elements do you already know?

Elements are represented by symbols One or two letters, first letter ALWAYS capitalized Oxygen-OAluminum- Al Hydrogen-HGold-Au Mercury-HgSodium-Na

COMPOUNDS Elements can exist uncombined or combined. A compound is a substance made of two or more elements in a specific ratio Compounds are represented by formulas A formula shows the ratio of elements in the compound Ex. H 2 O, CO 2, NaCl

Element or Compound?

Mixtures are made of two or more substances-elements, compounds, or both, that are together in the same place but are not chemically combined. Ex. Salt water, air, soup, salad

Compound vs. mixture? Substances in mixtures keep their individual properties. Ex. Chex mix Substances in compounds change their individual properties Ex. NaCl (salt)

Changes in Matter Physical changes alter the physical appearance but do not turn material into a new substance Changes in : Ex. Water melting, freezing, evaporating The water looks different, but it is still H 2 O

Chemical Changes Chemical changes or chemical reactions, change matter into new substances The change is permanent Ex. Burning paper, baking a cake, metal rusting

Chemical or Physical? Matter can change in one of two ways, physically or chemically

Ch. 1-2 Measuring Matter What is the difference between weight and mass?

Volume The amount of space an object occupies. To measure a rectangular object: V= Length x Width x Height

To measure a liquid, use a graduated cylinder

To measure and irregularly shaped object, use the displacement method

Density The measure of how much mass is contained in a given volume

A small block of wood floats on water. It has a volume of 2 cubic centimeters and a mass of 20 grams. What is the density?

Chapter 1-3 Particles of Matter

Early ideas about atoms Democritus-Greek philosopher, lived about 440 B.C. He called the smallest piece of a substance “atomos”, Greek for “uncuttable”

John Dalton-1802 Proposed atomic theory Imagined atoms to be like tiny marbles that are impossible to break

In any element, all the atoms are exactly alike Atoms of different elements are different Atoms of two or more elements can combine to form compounds Atoms of each element have a unique mass The masses of the elements in a compound are always in a constant ratio

Ideas about atoms today There are 2,000 billion billion atoms of oxygen in one drop of water

Atoms are linked by chemical bonds A combination of two or more atoms that are bonded together is a molecule