1/6/09

Today we took notes and talked about homework. The homework is P. 290 #'s 8, 10, 11, 13, 15, and 17. We also got a new worksheet handout but it is not due until a furthur date.

Notes

Section 2

Synthesis reactions

- In a synthesis reaction, also known as a composition reaction, 2 or more substances combine to form a new compound.

- This type of reaction is represented by the following equation.

- A + X= AX Where A and X can be elements or compounds and AX is a compound.

- Reactions of elements with oxygen and sulfur.

- One simple type of synthesis reaction is the combonation of an element with oxygen to produce an oxide of the element.

- Almost all metals react with oxygen to form oxides.

- Example: 2Mg(s) + O2(g) yeilds 2MgO(s)

- Group 2 elemets react in a similar manner, forming oxides with the formula MO, where M represents the metal.

- Group 1 metals form oxides with the formula M2O.

- Ex: Li2O

- The group 1 and group 2 elements react similarly with sulfur, forming sulfides with the formula M2S and MS, respectively.

16Rb(s) + S8(s) yields 8Rb2S(s)

8Ba(s) + S8(s) yields 8BaS(s)

- Nonmetals also undergo synthesis reactions with oxygen to form oxides.

- Ex: Sulfur reacts to form sulfur dioxide.

S8(s) + 802(g)

- Ex: Hydrogen reacts with oxygen to form digydrogen monoxide (water).

2H2(g) + O2(g) yields 2H2O(g)

- Reactions of metals with Halogens

- Most metals react with Group 17 elements, the halogens, to form either ionic or covalent compounds.

- Group 1 metals react with halogens to form ionic compounds with the formula MX where M is the metal and X is the halogen.

- Ex: 2Na(s) + Cl2(g) yields 2NaCl2

- Group 2 metals react with the halogens to form ionic compounds with the formula MX2.

- Ex: Mg(s) + F2(g) yields MgF2(s)

-Flourine is so reactive that it combines with almost all metals.

- Synthesis reactions with oxides

- Active metals are highley reactive.

- Oxides of active metals react with water to produce metal hydroxides.

- Ex: calcium oxide reacts with water to form calcium hydroxide.

CaO(s) + H2O(L) yields Ca(OH)2(s)

- Many oxides of nonmetals in the upper right of the periodic table react with water to produce oxyacids.

-Ex: SO2(g) + H2)(L) yields H2SO3(aq)

-Certain metals, oxides, and nonmetals oxides react with each other in synthesis reactions to form salts.

-Ex: CaO(s) + SO2(g) yields CaSo3(s).

Happy snow day I hope!!!!!!!!!!