8Th Science Chemical Reactions Ch.5

Front 1

Evidence for a ____ _____ is that the product of the new material has properties that are different from those of the starting materials.

Back 1

CHEMICAL REACTIONS

Front 2

What observable changes take place in the properties?

Back 2

Changes in state, color, temperature, smell etc

Front 3

What is a SOLID THAT FORMS from a solution during a chemical reaction.

Back 3

PRECIPITABLE

Front 4

What type of observable characteristics in energy are found during a chemical reaction?

Back 4

Some reactions ABSORB ENERGY
some release energy

Front 5

What do you call a reaction which ABSORBS energy?

Back 5

ENDOTHERMIC reaction

Front 6

What do you call a reaction that releases energy in the form of heat?

Back 6

EXOTHERMIC reaction

Front 7

What is chemical reaction on a small scale?

Back 7

when chemical bonds break or when new bonds are formed

Front 8

Chemical bonds are the ____ that holds atoms together in molecules

Back 8

force

Front 9

The types of ____ that are present and the type of ____ _____ they form determine the properties of the substance.

Back 9

atoms
chemical bonds

Front 10

What is a shorter easier way to show chemcical reactions, using symbols instead of words?

Back 10

Chemical equation

Front 11

How do you write a chemical equation

Back 11

identify the elemets in a compound as well as the ratio of these

Front 12

The number of atoms of an element in a molecule or the ratio of elements in a compound!

Back 12

SUBSCRIPTS

Front 13

WHAT DOES A CHEMICAL EQUATION TELL U?

Back 13

It tells you the substances you start with and the substances you end with.

Front 14

What do you call the materials that you have at the beginning of the reaction?

Back 14

REACTANTS

Front 15

What do you call the materials you have at the end of the reaction?

Back 15

PRODUCTS

Front 16

The theory that says "no matter how many reactants and products are involved, all the atoms present at the start of a reaction are present at the end" is called what?

Back 16

CONSERVATION OF MASS

Front 17

The amount of ____ in a chemical reaction does not change

Back 17

MASS

Front 18

During a reaction, matter is not _____ or _____.

Back 18

created or destroyed

Front 19

When you balance a chemical equation what must happen?

Back 19

the equation must show the same number of each type of atom on both sides of the equation.

Front 20

What do you call a number placed in front of a chemical formula in an equations?

Back 20

Coefficient

Front 21

A coefficient tells what?

Back 21

the number of molecules it preceds. Ex: 2CO2 means 2 - CO2 molecules
OR the number of atoms of each substance: Ex: 2Na means 2 -Na atoms

Front 22

When two or more substances combine to make a more COMPLEX SUBSTANCE, it is called what?

Back 22

SYNTHESIS

Front 23

What breaks down compounds into simpler products?

Back 23

DECOMPOSTION

Front 24

What is replacement?

Back 24

When one element REPLACES another in a compound OR when two elements in different compounds TRADE PLACES

Front 25

How do reactions get started?

Back 25

they need a certain amount of energy

Front 26

The minimum amount of energy needed to start a chemical reaction is called ?

Back 26

ACTIVATION ENERGY

Front 27

Which needs additonal energy to continue the reaction, EXOTHERMIC OR ENDOTHERMIC

Back 27

ENDOTHERMIC SO IT ABSORBS HEAT

Front 28

_____ does not need additional energy to continue so they give OFF HEAT.

Back 28

exothermic

Front 29

How do chemists control the rate of reactions?

Back 29

By changing factors such as concentration, temperature, and surface areas

Front 30

The amount of one material in a given amount of another material is called what?

Back 30

CONCENTRATION

Front 31

When you heat a substance, its PARTICLES MOVE FASTER and increase the reaction, which is called what?

Back 31

TEMPERATURE

Front 32

When you increase the surface area you increase the ____ of the solid that can contact with the other reactant

Back 32

amount

Front 33

What is a CATALYSTS?

Back 33

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

Front 34

What is a biological catalyst that is contained in the cells of living things?

Back 34

Enzymes

Front 35

An INHIBITOR _____ the rate of a reaction?

Back 35

decreases

Front 36

The rapid reaction between oxygen and fuel is called ______.j

Back 36

COMBUSTION

Front 37

A material that realeases energy when it burns is called ___?

Back 37

FUEL

Front 38

What is the Fire Triangle?

Back 38

3 things necessary to start and maintain a fire:
fuel
oxygen
heat