Everything is divided into two categories:Energy: the ability to do workMatter: anything that has mass and takes up space

Properties of Matter: characteristics that can be used to identify particular substances because these characteristics are always uniform (the same) in a particular substance. (examples: boiling point, hardness)

Two Kinds of Properties: •Physical Properties: This is a characteristic of a pure substance. The characteristic can be seen without making any changes to the substance. Examples: Density, hardness, texture, color, phase, ability to dissolve in water, and conductivity.

Two Kinds of Properties:•Chemical Properties: This is a characteristic of a pure substance. The characteristic can be seen when changing the substance into another substance. Examples: Flammability, production of a gas, and the ability to rust or tarnish.

•Characteristics that can be seen without making any changes to the substance?•Characteristic that can be seen when changing the substance into another substance? •Flammability?•Density?•Hardness? •Rust or tarnish? •Production of a gas?•Color?•Phase?

Physical

Chemical

ChemicalPhysicalPhysical Chemical ChemicalPhysicalPhysical

Element: a substance that cannot be broken down into smaller substances by ordinary chemical means. It is a pure substance, made up of only one kind of atom. Atom: The basic particle from which all elements are made. Molecule: two or more atoms that are chemically bonded to form a larger particle.

Compound: two or more elements combined chemically in definite proportions. The properties of the compound are different from the properties of the elements that make up the compound.Mixture: combination of two or more elements or compounds, which are NOT combined chemically, and NOT in definite proportions. Each substance keeps its own properties.

Types of Mixtures:•Heterogeneous Mixture: you can easily see the different substances.•Homogeneous Mixture: it is so evenly mixed, that you can NOT see the different substances that make it up. A solution, such as stirring sugar into your tea or the air in our atmosphere, is an example.

•A substance made of only one type of atom?

•Two or more substances, which are NOT combined chemically, and NOT in definite proportions?

•Two or more atoms that are chemically combined?

•The basic particle from which all elements are made?

•Two or more elements combined chemically in definite proportions?

Element

Mixture

Molecule

Atom

Compound

Physical Change: You have the same substance both before and after a physical change. The object changes in size, shape, or form. (Note: a change in phase is a physical change.)

Chemical Change: A change in the composition of materials creating a new substance with totally new properties. (You cannot get the old substances back.)

Law of Conservation of Matter: matter cannot be created or destroyed in a physical or chemical change.

Energy Changes: All changes in matter, physical and chemical, also include a change in energy. Examples:•Thermal Energy: this is all of the energy of all of the particles in an object.

•This is the most common change in energy when you have a change in matter. •Temperature is used to measure the average energy of the motion of particles in an object. •The flow of thermal energy will always be from warmer objects to cooler objects.

•Two types of thermal change:oEndothermic: energy is taken in or absorbed. (The matter being changed absorbs the heat so it feels cold.) oExothermic: energy is given off or released. Combustion is an example. (The matter feels warm or hot.)

Temp drops

•Chemical Energy: this is energy stored in the bonds that hold the atoms of a substance together. When a chemical change occurs, bonds are broken and new bonds form. Energy is released in the process.

•Electromagnetic Energy: this is energy that travels through space as waves. Examples: visible light, microwaves, and x-rays.•Electrical Energy: this occurs when electrically charged particles (electrons) move from one location to another.

Indicators of a Chemical Change:•Gas Liberation: a gas is formed and you observe bubbles•Heat and/or Light is Given Off: usually observed as burning•Color Change: the substance changes to a different color•Precipitate Forms: solid particles form in a liquid and sink to the bottom of the container.