1. The process by which the atoms of one or more substances are rearranged to form different substances is called a chemical reaction

2. Chemical reactions have taken place: a.When there is a temperature change b.Color change c.Odor, gas bubbles, and appearance of a solid

3. The starting substances of a chemical reactions are called the reactants. 4. The substances that are formed from the reactants are called the products.

5. The arrow sign in a chemical equation means “yields” or “reacts to produce” 6. In a chemical reaction the reactants are “used up” to make the products

7. The plus sign (+) in a chemical equation is used to separate two or more reactants or products. 8. The symbol (s) identifies the solid state. 9. The symbol (l) identifies the liquid state 10. The symbol (g) identifies the gaseous state. 11. The symbol (aq) identifies a water solution

12. A chemical equation must show that the number of atoms of each reactant and each product is equal on both sides of the arrow (balanced chemical equation).

13. Steps for balancing a chemical equation: a.Write the equation for the reaction. b.Count the atoms of the elements in the reactants. c.Count the atoms of the elements in the products. d.Change the coefficients to make the number of atoms of each element equal on both sides of the equation.

e. Never change a subscript in a chemical equation. f. Write the coefficients in their lowest possible ratios. 14. Balancing chemical equations adheres to the Law of Conservation of Mass.

15. There are 5 different types of chemical reactions: Synthesis Decomposition Single replacement Double displacement Combustion

16. In a synthesis reaction, two or more substances combine to form one new substance A + B → AB Two elements can combine to form a compound Na + Cl → NaCl Two compounds can combine to form a new compound NH 3 + HCl → NH 4 Cl A compound can combine with an element to form a new compound SO 2 + O 2 → SO 3

17. In a decomposition reaction, substances will break up, or decompose into simpler substances when energy is supplied. AB → A + B A compound can break down into two elements NaCl → Na + Cl A compound can break down into two compounds CdCO 3 → CdO + CO 2

18. In a single replacement reaction, one element displaces another in a compound. AB + C → AC + B A nonmetal can replace another nonmetal KBr + Cl 2 →KCl + Br 2 A metal can replace another metal AgNO 3 + Cu → Cu(NO 3 ) 2 + Ag Metal replaces hydrogen in a water molecule Li + H 2 O → LiOH + H 2

19. In a double displacement reaction, the positive and negative portions of compounds are interchanged. AB + CD → AD + CB PbCl 2 + Li 2 SO 4 → PbSO 4 + LiCl ZnBr 2 + AgNO 3 → Zn(NO 3 ) 2 + AgBr

20.All double replacement reactions produce either a : a.precipitate-solid b.gas c.water

21. In a combustion reaction, a hydrocarbon reacts with oxygen producing carbon dioxide and water. Hydrocarbon + oxygen → carbon dioxide + water CH 4 + O 2 → CO 2 + H 2 O C 4 H 10 + O 2 → CO 2 + H 2 O

When a substance dissolves in water, a solution forms. 23. A solution contains one or more substances called solutes dissolved in water. 24. The most plentiful substance in the solution (water) is the solvent.

25. An aqueous solution is a solution in which the solvent is water. 26. Possible solutes in an aqueous solution: a.Molecules (sugar, alcohol) b.Ions (chloride, hydrogen) 27. Compounds that produce hydrogen ions in aqueous solution are acids.

28. Double displacement reactions occur when two aqueous solutions that contain ions are combined. 29. Three types of products form from double displacement reactions: a.Precipitate b.Gas c.water

30. An ionic equation that shows all of the particles in a solution as they really exist is called a complete ionic equation. 2NaOH + CuCl 2 →2NaCl + Cu(OH) 2 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)→ 2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) 31. Ions that do not participate in a reaction are called spectator ions.

32. Ionic equations that include only the particles that participate in the reaction are called net ionic equations 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)→ 2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) 2OH - (aq) + Cu 2+ (aq)→Cu(OH) 2 (s)

33. No evidence of a chemical reaction is observable in a double displacement reaction that produces water molecules. HBr(aq) + NaOH(aq)→H 2 O + NaBr H+(aq) + Br-(aq) + Na+(aq) + OH-(aq)→H 2 O(l) + Na+(aq) + Br-(aq) H+(aq) + OH-(aq)→H 2 O(l)

34. Gases commonly produced in DD reactions are: Carbon dioxide Hydrogen cyanide Hydrogen sulfide