A pure substance made of two or more kinds of elements that are chemically combined in fixed proportions. Represented by a chemical formula. Examples – Water (H 2 O), Table Salt (NaCl)
Compounds are held together by Chemical bonds. Compounds are either ionic or covalent.
Atoms combine by sharing electrons to form molecules. Molecules are a group of atoms held together by sharing one or more pairs of electrons. Examples include carbon dioxide and water.
Covalent Compounds are formed from non-metals only. They do not conduct electricity. May be a solid, liquid, or gas at room temperature.
Examples of Covalent Compounds: Table sugar C 12 H 22 O 11 Carbon Dioxide CO 2 Water H 2 O Methane CH 4
Atoms gain or lose electrons to form ions. All the positive ions attract all the negative ions everywhere in the same crystal. Formed from metals and non-metals.
All are solid at room temperature. High melting and boiling points. Will conduct electricity when melted or dissolved in water. Are also called “salts”. CvzWwww&feature=related CvzWwww&feature=related
Examples of Ionic Compounds: NaClSodium Chloride CaCO 3 Calcium Carbonate Na 2 SO 4 Sodium Sulfite NaOHSodium Hydroxide
Compound Name Chemical Formula Element Names# of each Element Table SaltNaCl SugarC 12 H 22 O 11 Carbon DioxideCO 2 PropaneC3H8C3H8 WaterH2OH2O Calcium Carbonate CaCO 3
Every compound has a... 1.Name: indicates the elements present in the compound 2.Formula: indicates the symbols and ratio of each element present in the compound.
Ionic Compounds - See page 81-2 Covalent Compounds - See page 83 Complete practice problems on pages 82 &83
The metal ion's name does not change The non-metal's name ends in ide. Examples: AlCl 3 = aluminum chloride Na 2 S = sodium sulfide K 2 O = potassium oxide MgH 2 = magnesium hydride
In order to be effective in using prefixes to name compounds containing two non-metals, these prefixes must be committed to memory: mono- 1 hepta- 7 di- 2 octa- 8 tri- 3 nona- 9 tetra- 4 deca- 10 penta- 5 hexa- 6See pg 83
1. Write symbols of elements 2. Write number of atoms
Sulfur trioxide S O 3 2. Write number of atoms 1. Write symbols of elements If no prefix on 1 st atom, then 1 is implied and not written
dichlorine heptaoxide Cl O 2 7
dinitrogen tetraoxide N O 2 4
phosphorus pentachloride P Cl 1 5 Final Formula If no prefix on 1 st atom, then 1 is implied and not written PCl 5
dinitrogen trisulfide N S 2 3
Example #6: dichlorine heptaoxide Cl 27 O
di nitrogen monoxide N O 2 1 Final Formula If no prefix, then 1 is implied and not written 2 NO
CCl 4 carbonmonotetra 2. Write number of atoms 1. Write names of elements chlor ine ide If first prefix is mono, it is implied and not written 3. Add “ide” to ending of the second atom. carbon t etrachloride Final Formula