Chemistry 103 - States of Matter & Chemical vs. Physical Changes

Chemistry

The study of the composition, structure, and properties of matter and of the energy consumed or given off when matter undergoes a change

Matter

Anything that occupies space and has mass

Mass

Defines the quantity of matter in an object

Energy

The capacity to do work

States of Matter

Solid, Liquid, Gas

Solid Matter

atoms or molecules pack close to each other in fixed locations

Liquid Matter

Atoms or molecules pack about as closely as they do in solid matter, but they are free to move relative to each other, giving liquids a fixed volume but not a fixed shape

Gaseous Matter

atoms or molecules have a lot of space between them

Supercritical Fluid

Any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist

Low

Density of Gas

Indefinite

Shape of Gas

Weak

Strength of Intermolecular Forces in Gas

High

Density of Liquid

Indefinite

Shape of Liquid

Moderate

Strength of intermolecular forces in liquid

High

Density of Solid

Definite

Shape of Solid

Strong

Strength of intermolecular forces in solid

Indefinite

Volume of Gas

Definite

Volume of Liquid

Definite

Volume of Solid

Intermolecular Forces

How much forces attract or repel each other (how strongly they interact)

Solids

Particles move slightly, there is not much space between particles, generally incompressible, maintains voume

Allotropes

When a substance can exist in two or more different forms in the same physical state

Liquids

Closely packed, but have some ability to move around. Weaker attractions; cannot hold particles in place. Particles occupy volume and there is not much space between particles, generally incompressible. No definite shape

Gases

Particles are widely spaced and have freedom of motion. Very weak attractions do not hold particles together. Compressible since most of volume is empty space. No definite shape or volume

Element

A substance that cannot be chemically broken down into simpler substances (basic building blocks of matter)

Compound

A substance composed of two or more elements in fixed definite proportions (can also be broken down by chemical processes)

Molecule

A substance composed of two or more elements bonded in fixed definite proportions

Pure Substance

Made up of only one component and its composition is invariant (same physical and chemical properties throughout, cannot be separated into simpler substances by physical process)

Mixture

A substance composed of two or more pure substances in properties that can vary from one sample to another

Types of Mixtures

Homogeneous, Heterogeneous

Homogeneous

Components ARE distributed uniformly throughout the sample and have no visible boundaries or regions, composition and properties are consistent

Heterogeneous

Components ARE NOT distributed uniformly, and may have distinct regions of differen composition (they are also easier to separate)

Decanting

Carefully pouring off water into another container

Filtration

Traps one of the components in a filter -small molecules pass through pores in filter

Centrifugation

Spins samples at very high g-forces to pull unstable particles out of solution

Distillation

A process in which the mixture is heated to boil off the more volatile (lower boiling point) liquid; Separates homogeneous mixtures

Thin Layer Chromatography

Substances have varying affinity for a solvent and is carried up to a porous plate more rapidly

Physical Change

A process that does not change the chemical composition of a substance

Phase Changes

Changing the material's state requires changing the amount of kinetic energy the particles have, or limiting their movement

Chemical Change

A process that alters the chemical compositions of a substance (atoms rearrange, transforming the original substance into different substances).