1. The Dance of the Elements: Simple Chemical Reactions

2. 5 types of reactions Synthesis (S) Decomposition (D)
Single replacement (SR)
Double replacement (DR)
Combustion (C)

3. Visualizing chemical reactions is much like imagining the elements involved in a simple dance.
At a dance, people can pick a partner, separate and take a break, change a dance partner or change both dance partners.

4. At the beginning of a dance, partners join together.
When elements combine to form a new compound, this is called a SYNTHESIS REACTION.

5. Synthesis Reactions
Reaction
Elements combine to form a new compound that has different properties than the elements alone. Synthesis means “to make” and what happens in this reaction is that smaller parts create a new more complex compound.

6. Recognizing a Synthesis Reaction
All synthesis reactions follow the pattern
A + B  AB
Looking at a real reaction, like one below, two or more different elements/compounds combine to form one new compound
2Na (s) + Cl2 (g)  2NaCl (s)

7. There comes a time for partners to stop dancing and take a break.
When chemical compounds divide and break down into smaller components, this is called a DECOMPOSITION REACTION.

8. Decomposition Reactions
Decomposition occurs when a compound breaks down from a complex molecule into simpler substances. Decomposition means “to break down” or “decay.”

9. Recognizing a Decomposition Reaction
All decomposition reactions follow the pattern
AB  A + B
In an actual reaction, one larger compound breaks down into two or more smaller substances.
HgCl2 (s)  Hg (l) + Cl2 (g)

10. Dancers sometimes change partners
When chemical compounds change one partner for another, this is called a SINGLE DISPLACEMENT REACTION.

11. Single Displacement Reactions
In this reaction, a more reactive ion replaces a less reactive ion and a new compound is produced.

12. Displacement Reaction
Recognizing a Single
Displacement Reaction
This reaction follows the pattern
AB + C  AC + B
An actual single displacement reaction would free one ion and take up another ion
Mg (s) + 2 H2O (l)  Mg(OH)2 (l) + H2 (g)

13. Dancers can also change both partners
When two chemical compounds both exchange a partner, it is called a DOUBLE DISPLACEMENT REACTION.

14. Double Displacement Reactions
In this reaction, the more reactive ions pair to form a new compound and the less reactive pair also form a new compound.

15. Recognizing a Double Displacement Reaction
This reaction follows the pattern
AB + CD  AD + CB
A double displacement reaction would free ions to change partners
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)

16. It’s that simple!
Chemistry isn’t always difficult. By learning to recognize the four simplest types of chemical reactions, you have taken a big step towards learning how different chemicals interact with one another.

17. HOMEWORK READ lab CAREFULLY!!!!
HANDOUT: front : tell type for 1—6 , 8—14
Back : tell type for 1—15
Finish ch. 8 reading guide AND webquest for a late grade!!
BE READY FOR QUIZ ON TYPES OF REACTIONS NEXT CLASS PERIOD!!

18.
(you tube: types of chemical reactions intro.wmv)