MATTER - INTERACTIONS

VOCABULARY 1 Element – a pure substance that cannot be separated into simpler substances by physical or chemical means

Compound – a pure substance composed of two or more elements that are chemically combined

VOCABULARY 1 Subscript – a number written below and to the right of a chemical symbol in a formula

Superscript – a number written above and to the right of a symbol to show charge of an ion

Coefficient – a number placed in front of a compound to show how many of them there are

VOCABULARY 1 Chemical change – a change that occurs when one or more substances are changed entirely into new substances with different properties – not reversible

Physical change – a change of state, but not composition

BASIC BUILDING BLOCKS:

Element: pure substance made of only one kind of atom – not separable

Compound: substance that is made of two or more elements that are chemically bonded – can be separated by chemical means only.

BASIC BUILDING BLOCKS:

Heterogeneous Mixture- physical blend of two or more substances that are not uniform

Homogeneous mixture – a physical blend of two or more substances that have the same composition

Called a solution

VOCABULARY #2 Organic compounds – compounds

containing carbon (part of all living things)

Inorganic compounds – all other compounds not containing carbon

Chemical reaction - the process by which one or more substances change to produce one or more different substances

VOCABULARY 2 Endothermic – the term used to

describe a physical or chemical change in which energy is absorbed.

Exothermic – the term used to describe a physical or chemical change in which energy is given off.

Precipitate – a solid formed in a solution as a result of a chemical reaction

LAW OF CONSERVATION OF MASS Mass is neither destroyed nor created during ordinary chemical reactions or physical changes

pure chemical compound has a fixed proportion of elements

MATTER Has both physical and chemical

properties Physical property: characteristic that

can be observed or measured without changing the identity

melting point boiling point color of an apple phase change: IceWatervapor(steam)

WHAT ARE PHYSICAL PROPERTIES AND CHANGES?

Physical properties are used to observe and describe matter.

WHAT ARE PHYSICAL PROPERTIES AND CHANGES?

Physical properties include: appearance, texture, color, odor, melting point, boiling point, density, specific heat, and many others.

PHYSICAL CHANGE Changes in a substance that does not involve a change in the identity of the substance

Ex: grinding, cutting, boiling

CHEMICAL PROPERTY Substances ability to undergo changes that transform it into a different substance

EX: combustion - charcoal (carbon) burns in air CO2

Iron rust

CHEMICAL CHANGE One or more substances are converted into a different substance

When chemical or physical changes occur, Energy (E) is always involved.

WHAT IS A CHEMICAL CHANGE? alters the composition of the original matter.

Different elements or compounds are present at the end of the chemical change.

The atoms in compounds are rearranged to make new and different compounds.

5 SIGNS OF A CHEMICAL CHANGE1. Color Changes

5 SIGNS OF A CHEMICAL CHANGE2. Odor Changes

When you smell an odd order in foods such as chicken, pork of mayonnaise, you know that the food has undergone a chemical change.

5 SIGNS OF A CHEMICAL CHANGE3. Temperature Changes

Another sign of a chemical change is the release or gain of energy by an object. Energy can be released during a reaction, resulting in heat or light. Energy can be absorbed during chemical changes creating a decrease in temperature, like with this cold pack.

5 SIGNS OF A CHEMICAL CHANGE4. Production of Gases

The formation of a gas is a clue to chemical changes. The bubbles of gas that you observed form when an antacid is dropped into water is an example of change.

5 SIGNS OF A CHEMICAL CHANGE5. Production of Solid

Another clue that a chemical change has occurred is the formation of a solid. A solid that separates out of solution during a chemical change is called a precipitate. This curdled milk has precipitates inside.