Notes: Unit 2: Naming and Formula Writing

Transcription

1 Name: Regents Chemistry: Mr. Palermo Notes: Unit 2: Naming and Formula Writing

2 UNIT 2: NOMENCLATURE & FORMULA WRITING OBJECTIVE: BY THE END OF THIS VIDEO YOU WILL BE ABLE TO: LESSON 1: NAMING & FORMULA WRITING (BINARY COMPOUNDS) ü Identify the various parts of a chemical formula ü Identify binary compounds by name binary compounds RECALL Coefficient: in front of Formula Subscript: small # after an atom Subscript after ( ) multiply everything inside by that # How many atoms of each substance are in the formula 3Na 2 SO 4? Example: 2Ca(NO 3 ) 2 # of atoms of each substance in the formula above: 2Ca, 4N, 12O 1

3 ü Can you identify the various parts of a chemical formula RECALL Elements cannot be broken down by physical or chemical changes. Compounds are composed of 2 or more elements that can be broken down by chemical change. What type of matter can be broken down by physical changes? IONS Ions are elements with a charge. The reference table lists these charges for each element. If the element is positive, it is called a cation. Cations are named the same as the element. (Example: Ca=Calcium atom / Ca +2 =Calcium ion) If the element in negative, it is called an anion. Anions are named ending with -ide (Example: N=Nitrogen atom / N -3 = Nitride ion) Mg +2 K + O -2 F - Li + I - BINARY COMPOUNDS Binary Compounds consist of only two of elements. Example: NaCl NAMING BINARY COMPOUNDS Write the complete name of the first element. The second element should then be named using the first syllable with the ending -ide. NaCl sodium chloride KI potassium iodide MgCl 2 magnesium chloride Ca 3 N 2 calcium nitride 2

4 Li 3 P Al 2 S 3 SrBr 2 Rb 2 O BaSe CsI ü Can you identify binary compounds by name WRITING CHEMICAL FORMULAS Sum of charges (oxidation numbers) in a compound equal zero Ex. Na +1 Cl -1 (+1) + (-1) = 0 WRITING FORMULAS 1. Write each ion separately with their charges 2. CRISS CROSS & REDUCE the charges not the signs 3. Write numbers as subscripts 4. Do not write 1 s Compound containing Magnesium and Chlorine Mg +2 Cl -1 MgCl 2 Compound containing Barium and Oxygen Ba +2 O -2 BaO Ba 2 O 2 3

5 Calcium and Fluorine ü Can you construct chemical formulas for binary compounds CaF 2 YOU SHOULD BE ABLE TO: ü Identify the various parts of a chemical formula ü Identify binary compounds by name binary compounds LESSON 2: NAMING & FORMULA WRITING (MULTIPLE CHARGES) OBJECTIVE: BY THE END OF THIS VIDEO YOU WILL BE ABLE TO: ü Identify binary compounds containing multiple charges by name using roman numerals binary compounds containing multiple charges PROBLEM: FeCl 2 and FeCl 3 are different compounds but seem to have the same name. How can we name them different? FeCl 2 is iron (II) chloride chloride. FeCl 3 is iron (III) What do the roman numerals represent? 4

6 TRANSITION METALS AND NONMETALS Transition Metals are in the middle group of the periodic table. Nonmetals are on the right side of the staircase. TRANSITION METALS AND NONMETALS They can have multiple charges or oxidation numbers and so you must show which charge you are using with roman numerals: Example: Iron (II) oxide HOW TO DETERMINE THE CHARGE? 1. Find the charge of the anion (the element listed last in the formula) It will always be negative charge 2. Set the whole thing equal to zero (since compounds are always neutral) 3. Then solve for the the charge of the cation NAMING BINARY COMPOUNDS CONTAINING MULTIPLE CHARGES 4. Now name the compound as you did in lesson 1 except you indicate the charge of the cation (first element) with roman numerals Example: FeCl 3 FeCl 2 CuF N 2 O 3 SO 4 Ni 2 O 3 PCl 3 5

7 ü Can you identify binary compounds containing multiple charges by name using roman numerals WRITING CHEMICAL FORMULAS Example: cobalt (II) chloride chromium (III) oxide nitrogen (II) fluoride ü Can you construct chemical formulas for binary compounds containing multiple charges YOU SHOULD BE ABLE TO: ü Identify binary compounds containing multiple charges by name binary compounds containing multiple charges OBJECTIVE: BY THE END OF THIS VIDEO YOU WILL BE ABLE TO: LESSON 3: NAMING & FORMULA WRITING (TERTIARY COMPOUNDS) ü Identify tertiary compounds containing polyatomic ions by name tertiary compounds containing polyatomic ions 6

8 TERTIARY COMPOUNDS When compounds have more than 2 elements, it contains a polyatomic ion (TABLE E). Polyatomic ion are a group of 2 or more atoms that are bonded very strongly and act as one ion. They bond with other ions to for compounds. Example: NO 3-1 NAMING TERTIARY COMPOUNDS Follow same rules as naming binary compounds except: The polyatomic ions on TABLE E are named according to the table Example: NaNO 3 Sodium Nitrate CaCO 3 calcium carbonate LiClO 2 lithium chlorite NaOH sodium hydroxide (NH 4 ) 3 PO 4 ammonium phosphate ü Identify tertiary compounds containing poly atomic ions by name WRITING FORMULAS CONTAINING POLYATOMIC IONS Same as Binary Compounds - Never change the polyatomic ion subscripts - If more than 1 polyatomic ion put in parenthesis followed by subscript Write the formula for ammonium chloride NH +1 4 Cl -1 NH 4 Cl 7

9 Write the formula for Lithium Carbonate Write the formula for Calcium Hydroxide Li +1 CO 3-2 Li 2 CO 3 Ca +2 OH -1 Ca(OH) 2 tertiary compounds containing polyatomic ions YOU SHOULD BE ABLE TO: ü Identify tertiary compounds containing polyatomic ions by name tertiary compounds containing polyatomic ions 8