Chapter 1 - Introduction

Chemistry - The study of matter and its changes

• Matter - Anything that has mass and takes up volume

Composition vs. Structure

• Composition - What something is made of
• Structure - What something is made of and how the components are arranged

Atom - The fundamental unit of matter

Element - Made of only one type of atom

Compounds - Composed of more than one element; bound in fixed ratios

Molecules - Groups of atoms that bind tightly together, and behave as a single unit

• Diatomic molecules - an element bound to another of itself

Pure substances - Composed of one element or one compound ONLY

Mixtures - contain more than one substance, not bound in a fixed ratio

• Alloys - mixtures of metals
• Homogenous - components mix evenly
• Heterogenous - component do not mix evenly
• Mixtures can be - separated into their components without changing the identity of the substance, unlike compounds

Matter -----> Pure Substances vs. Mixtures

Pure Substances -----> Elements (Gold) vs. Compounds (Water)

Mixtures -----> Homogenous (Air) vs. Heterogenous (Salt and Water)

The Three States of Matter

• Solid - Definite volume and shape

• Liquid - Definite volume, but no definite shape

• Gas - No definite anything

  

Deposition = Condensation

The behavior of any substance is determined by the arrangement of the particles that compose the substance.

Properties and Changes

• Physical properties - Can be measured without changing the identity of the substance
• Physical changes - Don’t change the identity of the substance
  • Phase Changes are Physical Changes
• Chemical properties - Can NOT be measured without changing the identity of the substances
• Chemical changes - Change the identity of the substances
  • Chemical Reactions

Elements combine to form new substances - A chemical change

A change that forms new compounds - A chemical change

CHEMICAL CHANGES IDENTITY, PHYSICAL DOES NOT CHANGE IDENTITY

Energy and Change

Energy - the ability to do work

• Potential energy - Stored energy
• Kinetic energy - Energy of motion

Heat energy - Involved kinetic energy of the particles in a substance

Physical and Chemical involve changes in energy

High energy or stable?

High energy - brings changes

Stable - no reaction

Exothermic change - Releases heat energy (Unstable Product)

Endothermic change - Absorbs heat energy (Stable product)

The Scientific Method

Make observations, formulate ideas, test ideas with experiments, and repeat

Hypothesis - A tentative explanation that has been tested

Theory - Idea supported by experimental evidence, or a paradigm

• Paradigm - A way of thinking about a topic

Scientific law - A statement that describes observations that are widely varying circumstances

A theory is how or why it happens, A law is what happens