NAMING IONIC COMPOUNDS

Transcription

1 NAMING IONIC COMPOUNDS 1

2 WHAT ARE IONIC COMPOUNDS Ionic compounds are formed between elements that are in ionic form. A simpler way of determining whether a compound is ionic is to see if there are any metals within the compound. Ionic compounds are formed between metals and non-metals or between metals and polyatomic ions. 2

3 RULES FOR NAMING IONIC COMPOUNDS For now we will focus only on the main group elements; transition metals are a bit tricky. In order to form an ionic compound you must have a cation (usually a metal) + an anion (usually a nonmetal). You always name the cation first, followed by the anion and replace the ending of the anion with -ide. 3

4 WHAT ELEMENTS BELONG TO THE MAIN GROUP?? 4

5 EXAMPLE In order to name NaCl. 5

6 MAIN GROUPS CHARGES Elements found under the main group have set charges. Charges represents how many electrons the element can lose or gain. Notice how every metal has a positive charge and non-metals have negative charges. Also, the charges are set for all elements belonging to a column. 6

7 CHARGES 7

8 WRITING IONIC COMPOUNDS In order to form a compound the overall charges of the compound must be zero. Therefore, if you have a cation with a 3+ charge and an anion with a 2- charge, you will need 2 of the cation and 3 of the anion. 8

9 EXAMPLE To combine magnesium and nitrogen to form magnesium nitride you first have to look at their charges. Mg 2+ and N 3-. The common factor between the two is 6, so you want to make the charges for each equal to 6. 9

10 EXAMPLE Mg 3 N 2 ; the small numbers indicates how many of each element are found in the compound. By having 3 Mg you have 6+ charge. By having 2 N you have 6- charge. Together they have a netcharge of zero. 10

11 PRACTICE PROBLEM Name the following compounds: 1. MgO 2. Na 2 S 3. KF 4. Ca 3 P 2 5. LiBr Answers 1. Magnesium oxide 2. Sodium sulfide 3. Potassium fluoride 4. Calcium phosphide 5. Lithium bromide 11

12 PRACTICE PROBLEM Write a compound with the following elements: 1. Oxygen and lithium 2. Strontium and nitrogen 3. Barium and chlorine Answers: 1. Li 2 O 2. Sr 3 N 2 3. BaCl 2 12

13 NAMING IONIC COMPOUNDS WITH TRANSITION METALS The rules for transition metals are almost the same as for regular metals. However, unlike main-group metals, transition metals have multiple charges. Therefore, when naming the compound you have to specify which charge the metal is carrying. This is indicated by using roman numerals. 13

14 A FEW EXAMPLES 14

15 HOW TO MAKE A COMPOUND WITH TRANSITION METALS If you have chromium (II) and you want to make a compound using sulfur, you have to look at the charges for each ion and find a common multiple. Chromium (II) has a 2+ charge and sulfur has a set charge of 2-. Therefore, you need one of each element to make a compound. The compound formula would be CrS. 15

16 PRACTICE PROBLEMS Make a compound using the following elements: Copper (I) and oxygen Tin (II) and nitrogen Lead (IV) and phosphorus Gold (I) and iodine Gold (III) and chlorine Answers: Cu 2 O Sn 3 N 2 Pb 3 P 4 AuI AuCl 3 16

17 COMPOUND TO NAMING When naming a compound that contains a transition metal in it you need to use roman numerals to indicate the charge of the cation. In order to do so you have to refer to the anion to figure out what the charge of the cation is. 17

18 EXAMPLE If you are given the compound MnO and were asked to name it you would: Look at the anion, which is the oxygen. You know that oxygen always has a charge of 2-. Since there is only one oxygen, in order for the formula to have a balanced charge manganese has to carry a charge of 2+. Therefore, the name of the compound is manganese (II) oxide. 18

19 PRACTICE PROBLEMS Name the following compounds: CrP Co 3 N 2 HgO FeS SnBr 2 PbO 2 Answers: Chromium (III) phosphide Cobalt (II) nitride Mercury (II) oxide Iron (II) sulfide Tin (II) bromide Lead (IV) oxide 19

20 NAMING IONIC COMPOUNDS WITH POLYATOMIC IONS Polyatomic ions are ions that contains more than one element in it. It is very important to know your polyatomic ions and its charges. 20

21 POLYATOMIC IONS 21

22 NAMING IONIC COMPOUNDS WITH POLYATOMIC IONS When naming compounds that contains polyatomic ions you name the cation as you normally would, and simply name the polyatomic element. Example: MgSO 4 will be named magnesium sulfate. 22

23 NAMING IONIC COMPOUNDS WITH TRANSITION METALS AND POLYATOMIC IONS When naming compounds that contains both a transition metal and a polyatomic ion you still have to use roman numerals for the metal, and the polyatomic ion will be named as is. Example: Cu 3 (PO 4 ) 2 will be named copper (II) phosphate. 23

24 PRACTICE PROBLEMS Name the following compounds: Sr(NO 2 ) 2 AuSO 3 Answers: Strontium nitrite Gold (II) sulfite Aluminum cyanide Al(CN) 3 24

25 DAILY DOSE OF JOKE 25