1. CHEMICAL REACTIONS
Chapter 3.1

2. Atoms interact in chemical reactions
Chemical Reaction: produces new substances by changing the way in which atoms are arranged.
Recall…
Physical Change: changes in the state of matter, but it is still the same substance
Chemical Change: original substance changes into a completely new substance; cannot be undone

3. Reactants vs products
Reactants: The substances present at the beginning of the chemical reaction
Products: The substances formed by a chemical reaction

4. Evidence of chemical reactions
Color change
Formation of a precipitate
Precipitate: solid product formed when chemicals in two liquids react
Formation of a Gas
Temperature Change

5. Types of chemical reactions
Synthesis: a new compound is formed by the combination of simpler reactants.

6. Types of chemical reactions
Decomposition: a reactant breaks down into simpler products, which could be elements or other compounds.

7. Types of chemical reactions
Combustion: One reactant is always oxygen and another reactant often contains carbon and hydrogen. The carbon and hydrogen atoms combine with oxygen, producing carbon dioxide and water.

8. THE RATES OF CHEMICAL REACTIONS CAN VARY
CONCENTRATION
MEASURES THE NUMBER OF PARTICLES PRESENT IN A CERTAIN VOLUME
A HIGH CONCENTRATION MEANS THERE IS A LARGE NUMBER OF PARTICLES COLLIDING AND REACTING.
HIGHER CONCENTRATION  INCREASED REACTION RATE

9. THE RATES OF CHEMICAL REACTIONS CAN VARY
SURFACE AREA
BREAKING A LARGE PIECE OF MATERIAL INTO SMALLER PIECES INCREASES THE SURFACE AREA OF THE MATERIAL. MORE SURFACES ARE EXPOSED.
INCREASED SURFACE AREA  INCREASED REACTION RATE

10. THE RATES OF CHEMICAL REACTIONS CAN VARY
TEMPERATURE
AS TEMPERATURE INCREASES, PARTICLES MOVE FASTER.
AS A RESULT, MORE COLLISIONS TAKE PLACE PER SECOND AND OCCUR WITH GREATER FORCE.
INCREASED TEMPERATURE  INCREASED REACTION RATE

11. THE RATES OF CHEMICAL REACTIONS CAN VARY
CATALYSTS
CATALYST: SUBSTANCE THAT INCREASES THE RATE OF REACTION BUT IS NOT ITSELF CONSUMED IN THE REACTION
THE CATALYST REMAINS UNCHANGED AFTER THE REACTION.
IN LIVING THINGS, CATALYSTS CALLED ENZYMES ARE NECESSARY FOR LIFE.

12. Video: Types of Chemical Reactions Video: Rate of Chemical reactions