Compounds Characteristics of Compounds Formation of Compounds Formulas and Naming Acids and Bases

Characteristics of Compounds Compound – two or more different elements that are chemically combined. Chemical change – a change that produces one or more new substances with new chemical properties. –Oxidation, burning, nuclear reactions Physical change – a change in which the appearance of a substance changes but its chemical properties stay the same. –Phase changes, shape and size changes

Changes ChangeChemical or Physical How do you know? 1. Melting ice cream 2. Rusting a nail 3. Chopping onions 4. Baking a cake 5. Coloring hair

Formation of Compounds Atom is made of a nucleus, which contains protons and neutrons. Most of the mass is found in the nucleus. The electrons are found in energy levels surrounding the nucleus. The number of energy levels is equal to the row number on the periodic table. –H and He are in row 1, therefore 1 energy level. –K, Ca, and Br and in row 4, therefore 4 energy levels.

Formation of Compounds Atoms combine to form compounds by bonds. –Chemical bond – an attractive force that holds atoms together –Ionic bond – a type of bond that occurs when an atoms transfers an electron to another atom –Covalent bond – a type of bond that occurs when two atoms share electrons

Formation of Compounds Ionic Compounds Any atoms in Column IA or IIA that forms a bond with any atom in Column VIA or VIIA –NaCl –CaO –MgF 2 –LiS 2 –KI Covalent Compounds Any atoms in any other columns that form bonds. –CO 2 –H 2 O (exception) –AlF 3 –Ba 3 N 2 –C 6 H 12 O 6

Electrons in energy levels Each energy level can only hold a certain number of electrons. NameNumber of e when filled K2 L8 M18 N32

Carbon Atom Carbon has 6 electron and is in row 2. Two electrons fill it’s first level and 4 fill it’s next level. The outside energy level can hold up to 8, so it can hold four more electrons

Oxygen Atom Oxygen has 8 electrons and is row 2. Two electrons fill the first energy level and 6 fill the second energy level. The outside energy level can hold up to 8, so it can hold 2 more electrons.

Calcium Atom Calcium is has 20 electrons and is in row 4. 1 st = 2 e, 2 nd = 8 e, 3 rd = 8 e, 4 th = 2 e

Chlorine Atom Chlorine is has 17 electrons and is in row 3. 1 st = 2 e, 2 nd = 8 e, 3 rd = 7 e

Chemical Formulas Formula – tells the kinds of atoms and how many of each kind are in a compound –CO 2, H 2 O, HCl, NaCl, C 6 H 12 O 6 Radical – a group of two or more atoms that acts like one atom –SO 4 : sulfate, NO 3 : nitrate, CO 3 : carbonate, OH: hydroxide

Chemical Formulas Al(OH) 3 CO 2 H 2 O H 2 SO 4 1 aluminum and 3 hydroxides 1 carbon and 2 oxygens 2 hydrogens and one oxygen 2 hydrogens, 1 sulfur, and 4 oxygens

Naming Compounds Binary compound – compound that contains only two elements The first name of a compound is the same as the name of the first element in the compound’s formula. The second name of a compound is the name of the second element in the compound’s formula with the ending changed to –ide.

Common Ending Names Chlorine (Cl) Iodine (I) Fluorine (F) Bromine (Br) Oxygen (O) Sulfur (S) Chloride Iodide Fluoride Bromide Oxide Sulfide

Naming Compounds NaCl BaO CaF 2 MgS Li2O BeI 2 Sodium Chloride Barium Oxide Calcium Fluoride Magnesium Sulfide Lithium Oxide Beryllium Iodide

Naming Compounds Al(OH) 3 BaSO 4 Ca(OH) 2 AgCO 3 Mg(NO 3 ) 2 Aluminum Hydroxide Barium Sulfate Calcium Hydroxide Silver Carbonate Magnesium Nitrate

Acids and Bases Acids taste sour. Acids contain hydrogen, usually in the front of the formula. Acids react with metals to produce hydrogen. HCl, H 2 SO 4, HCO3 Bases taste bitter. Bases contain hydroxide radical, usually at the end of the formula. Bases feel slippery. NaOH, Ca(OH) 2, MgOH

Acids and Bases Indicator – a substance that changes color to identify an acid or base. Litmus paper – acids turn litmus red, bases turn litmus blue pH – a number that tells whether a substance is an acid or base –pH < 7 = acid –pH > 7 = base –pH = 7, neutral