College Chemistry chapter 1

Chemistry

The study of structure, properties, and behavior of matter

Matter

Anything that has mass and volume

Pure substance

A type of matter that has the same composition from sample to sample

Element

Pure substance that cannot be decomposed by physical or chemical means

Atom

Building block of an element

Compound

Pure substance with a definite composition made up of two or more elements that can be chemically decomposed

Law of Constant Composition

The relative number of atoms in any sample is the same in all samples

Mixture

Impure material that can be physically separated into 2+ substances. Exhibits properties of what makes it up

Heterogeneous mixture

Mixture in which the uneven texture is visible to the naked eye

Homogenous mixture

(Also known as solution) completely uniform texture, two or more substances present in unequal amounts, same proportions throughout sample, same physical state

Physical properties

Properties observed without a substance change; examples include boiling point, density, freezing piint

Chemical properties

Properties that can only be observed through chemical changes to a different substance; examples include flammability, reaction to acid, corrosiveness

Intensive properties

Properties of a substance that are independent of the amount of substance present; examples include density, temperature

Extensive properties

Properties dependent on the amount of substance present; includes volume, mass, and energy

Solid

Definite shape and volume, particles packed together in a fixed shape

Liquid

Definite volume but no definite shape; particles close together

Gas

No definite shape or volume; particles are far away from each other

Plasma

High temperature and ionized phase of matter found on the sun

Physical change

Conversion between the states of matter that do not change the amount of substance present

Chemical changes

Result in new substances

Methods of separating a heterogenous mixture

Filtration, centrifugation, suspension

Colloids

Mixture with properties between homogenous and heterogenous mixtures

Immiscible

Insoluble

Emulsion

Mixture that clearly separates into two Immiscible liquids

Distillation

Method of separating a homogenous mixture that uses boiling points to separate the components

Chromatography

Used to separate homogenous mixtures. Based on differences in molecular attraction to the transporting medium. Separates substances based on their ability to adhere to the medium

Random error

Measurement has an indeterminate probability of being high or low

Systematic error

Often results from poor calibration or human error, and often occurs in the same direction each time (high or low)

Exact numbers

Numbers that are given by definition or are counted

Inexact numbers

Numbers that depend on how they were determined

Mass

The amount of something there is; the SI unit is a kilogram; metric unit is a gram

Volume

Metric units are liters and milliliter (also called a cubic cm)

Length

A measure of distance; base unit is meter

Celsius

Temperature scale based in properties of water

Kelvin

Temperature scale based in properties of water