Matter and Change Chapter 1

What is Chemistry?

What does Chemistry do? Chemistry deals with questions such as: What is that material made of? What is its makeup and internal arrangement? How does it behave and change when heated, cooled, or mixed with other materials and why does this behavior occur?

Branches of Chemistry Organic chemistry Inorganic chemistry Physical chemistry Analytical chemistry Biochemistry Theoretical chemistry

chemicals  any substance that has definite composition

Matter and its Properties Explaining what matter is involves finding properties that all matter has in common

Basic Building Blocks of Matter Atoms – the smallest unit of an element that maintains the properties of that element Molecules- a neutral group of atoms that are held together by covalent bonds

An element is a pure substance made of only one kind of atom. A compound is a substance that is made from the atoms of two or more elements that are chemically bonded.

Properties of Matter

Every substance, whether it is an element or a compound, has characteristic properties.

Extensive properties Intensive properties

Mixtures A mixture is a blend of two or more kinds of matter. It can usually be separated by physical means.

Homogeneous mixtures are uniform in composition, stays the same throughout. (A.K.A. solutions.) Heterogeneous mixtures are not uniform in composition.

Pure Substances A pure substance has a fixed composition and differs from a mixture in the following ways: Every sample of a given pure substance has exactly the same characteristic properties and exactly the same composition.

Pure substances are either compounds or elements. A compound can be decomposed, or broken down into two or more simpler compounds or elements by a chemical change.