CHEMISTRY LESSON 1

Matter

Anything that occupies space and has mass.

Atom

A tiny particle that makes up matter and consists of smaller subatomic particles such as electrons, protons, and neutrons.

Three main states of matter

Solid, liquid, and gas.

Solid state

Its molecules have restricted motion and are tightly bound to one another. It has a fixed volume and fixed shape.

Liquid state

Its molecules move freely and are weakly attracted to one another. It has a fixed volume but an indefinite shape.

Gas state

Its molecules have chaotic movement and very weak attraction to one another. It has an indefinite volume and indefinite shape.

Plasma

A special type of gas in which some atoms have become free-floating ions and free electrons.

Supercritical fluids

Highly compressed gases that combine the properties of gases and liquids.

Degenerate matter

Basically a collapsed state of matter.

Degeneracy

A state of matter used to explain the existence of black holes, white dwarf stars, and other theorized states.

Phase transition

A physical change in which a substance changes because of temperature or pressure without changing its chemical composition.

Physical properties

Properties that can be measured without changing the chemical composition of a substance.

Examples of physical properties

Color, texture, odor, and taste.

Chemical properties

Properties that can be measured by changing the chemical composition of a substance through a chemical process.

Examples of chemical properties

Flammability, radioactivity, toxicity, and oxidation.

Intensive properties

Physical properties that do not depend on the amount of a substance.

Examples of intensive properties

Malleability, boiling point, freezing point, and ductility.

Extensive properties

Physical properties that depend on the amount of a substance.

Examples of extensive properties

Mass, length, volume, and shape.

Physical change

A change that does not alter the identity of a substance.

What may change during a physical change?

The shape, size, state, or appearance of a substance.

Example of a physical change

A gold bar being hammered or molded to create jewelry.

Chemical change

A change that produces a new substance with a different chemical composition and different properties.

Signs of a chemical change

Formation of a precipitate, production of gas, color change, or release of energy in the form of heat.

Two classifications of matter

Pure substances and impure substances.

Pure substance

A substance that cannot be separated or broken down by physical means.

Two types of pure substances

Elements and compounds.

Element

The simplest type of substance, composed of only one kind of atom, that cannot be broken down into simpler forms.

Examples of elements

Gold, zinc, mercury, and chlorine.

Compound

A substance made from two or more different kinds of atoms or elements that can be broken down into simpler forms.

Examples of compounds

Sodium chloride, calcium carbonate, sodium hydroxide, and copper sulfate.

Three classifications of elements

Metals, nonmetals, and metalloids.

Properties of metals

Good electrical and heat conductors, malleable, ductile, have metallic luster, opaque as thin sheets, and solid at room temperature except mercury.

Properties of nonmetals

Poor electrical and heat conductors, brittle, nonductile, lack metallic luster, transparent as thin sheets, and may be solid, liquid, or gas at room temperature.

Properties of metalloids

Have properties intermediate between metals and nonmetals, may be shiny or dull, and are semiconductors.

Impure substance

Another term for a mixture whose components can be separated by physical means.

Mixture

A form of matter whose components are not chemically combined and can be separated through physical means.

Two types of mixtures

Homogeneous mixtures and heterogeneous mixtures.

Homogeneous mixture

A mixture in which only one phase is visibly seen.

Examples of homogeneous mixtures

Brewed coffee, air, steel, and saline solution.

Solution

A homogeneous mixture composed of a solute and a solvent.

Solute

The substance that is being dissolved in a solution.

Solvent

The dissolving medium in a solution.

Saturated solution

A solution containing the maximum amount of solute that the solvent can dissolve.

Unsaturated solution

A solution containing less than the maximum amount of solute that the solvent can dissolve.

Supersaturated solution

A solution containing more than the usual maximum amount of dissolved solute.

Heterogeneous mixture

A mixture in which at least two different phases are visibly seen.

Examples of heterogeneous mixtures

Mist, assorted candies, and smog.

Suspension

A heterogeneous mixture with particles large enough to settle at the bottom. It also exhibits the Tyndall effect.

Colloid

A mixture intermediate between a solution and a suspension. Its particles do not separate, but it exhibits the Tyndall effect.

Tyndall effect

The scattering of visible light by particles in a colloid or suspension.

Separatory funnel

A method used to separate two immiscible liquids with different densities, such as benzene and water.

Simple distillation

A method used to separate two miscible liquids with enough difference in their boiling points, such as acetone and water.

Fractional distillation

A method used to separate two or more miscible liquids whose boiling-point difference is less than 25°C, such as ethanol and water.

Evaporation

A method used to separate a soluble solid from a liquid, such as salt from a salt-water solution.

Filtration

A method used to separate an insoluble solid from a liquid, such as sand from water.

Centrifugation

A method used to separate smaller insoluble solids from a liquid when normal filtration does not work well.

Example of centrifugation

Blood testing.

Chromatography

A method used to separate components based on their different solubilities in a mobile phase and stationary phase.

Example of chromatography

Separating food coloring or ink.

Magnetism

A method used to separate two solids when one has magnetic properties.

Example of magnetic separation

Separating iron filings from sand.