Ch 7 Vocabulary-physical science

Name: _Ms. Long__________________________________________ Date: _______________ Period: __________________

Chapter 7 Vocabulary (PS)

Word

Illustration

Definition

 

Activation Energy

 

 

minimum amount of energy

The minimum amount of energy needed to start a chemical reaction

 

Catalyst

 

 

increases the rate

A material that increases the rate of a reaction by lowering the activation energy

 

Chemical change

 

 

form new substances

A change in which one or more substances combine or break apart to form new substances

 

Chemical equation

 

using symbols

A short, easy way to show chemical reactions, using symbols

 

Closed system

 

 

which no matter is allowed to enter

A system in which no matter is allowed to enter or leave

 

Coefficient

 

 

A number in front

A number in front of a chemical equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction

 

Concentration

 

 

certain volume

The amount of one material in a certain volume of another material

 

Decomposition

 

 

breaks down

A chemical reaction that breaks down compounds into simple products

 

Endothermic reaction

 

absorbs

A reaction that absorbs energy

 

Enzyme

 

 

 

1. a type of protein that speeds up a chemical reaction in a living thing

2. a biological catalyst that lowers the activation energy of reactions in cells

 

 

 

Exothermic reaction

 

 

 

Release energy

 

 

A reaction that releases energy, usually in the form of heat

 

Inhibitor

 

 

Decreases rate

A material that decreases the rate of a reaction

 

Law of conservation of Mass

 

Not created or destroyed

The principal that the total amount of matter is neither created or destroyed during any physical or chemical change

 

Open system

 

 

matter can enter from or escape

A system in which matter can enter from or escape to the surroundings

 

Physical Change

 

 

does not make

A change that alters the form or appearance of a material but does not make the material into another substance.

 

Precipitate

 

 

forms from a solution during

A solid that forms from a solution during a chemical reaction

 

Product

 

 

formed

A substance formed as a result of a chemical reaction

 

Reactant

 

 

enters

A substance that enters into a chemical reaction

 

Replacement

 

 

trade places

A reaction in which one element replaces another in a compound or when two elements in different compounds trade places

 

Synthesis

 

 

a new, more complex substance

A chemical reaction in which two or more simple substances combine to form a new, more complex substance