1. SNC2P Ions and Ionic Compounds

2. Forming Ions In an atom the number of protons equals the number of electrons. If electrons are added to an atom, the atom now has more negatives than positives. It has a negative charge. This is an anion. If electrons are removed from an atom, the atom now has more positives than negatives. It has a positive charge. This is a cation.

3. Naming Ions To name a Cation (positively charged ion), write the element name followed by the word ion. Mg 2+ is called Magnesium Ion To name an Anion (negatively charged ion), write the name of the element and change the ending to “ide” S 2- is called Sulfide

4. Writing Ionic Symbols From Names When given the name of an ion and the ending does not have “ide”, then you know this is a positive ion. Write the element’s symbol with a positive charge (recall the valence electron trends to know what the charge is). The symbol for Potassium Ion is K 1+ When given the name of an ion that ends in “ide”, you know it is a negative ion. Write the element’s symbol with a negative charge (recall the valence electron trend to know what the charge is). The symbol for Nitride is N 3-

5. Transition Metals The elements in columns 3 to 12 are called the Transition Metals. Transition Metals are always positive. To know what the charge is you will have to look at the Roman Numeral in the name. Iron (III) means Fe 3+ Nickel (II) means Ni 2+

7. Traditional and Stock System Names of Transition Metals You will be given a table of traditional names for transition metals. Some examples of traditional names are Ferrous (Fe 2+ ) and Ferric (Fe 3+ ). The system we mostly use in this class is the Stock System. In the Stock System, Fe 2+ would be Iron (II) and Fe 3+ would be Iron (III).

8. Forming Ionic Compounds Substances that are composed of cations and anions are called ionic compounds (compounds made up of ions). When the ions combine the overall charge of the compound that is formed must be neutral. K + and Cl - will combine to form KCl

9. Forming Ionic Compound Examples Ca 2+ and Cl 1- will form CaCl 2 Because it will take two negative chlorines to balance one positive calcium. Na + and S 2- will form Na 2 S Because it will take two positive sodiums to balance one negative sulfur. Al 3+ and P 3- will form AlP Because it will take one positive aluminum to balance one negative phosphorus. Al 3+ and O 2- will form Al 2 O 3 Because it will take two positive aluminums to balance three negative oxygens.

10. The Trick to Forming Ionic Compounds Be 2+ and P 3- Take the number part of the charge and put it on the bottom left hand side of the other ion. Be 3 P 2

11. Polyatomic Ions Atoms can combine in groups to form ion complexes. These are called polyatomic ions. An example of a polyatomic ion is Phosphate (PO 4 ) 3- Other examples are Sulfite (SO 3 ) 2- and Ammonium (NH 4 ) 1+ There is a table of common polyatomic ions that will be available for you to use.

12. Forming Compounds Using Polyatomic Ions The trick that was used to make binary ionic compounds (compounds made from 2 ions) can also be used to form polyatomic compounds. Mg 2+ and (PO 4 ) 3- forms Mg 3 (PO 4 ) 2

13. Naming Ionic Compounds When Given The Formula Identify the ions in the compound Name the ions in the compound Change the ending on the second element to “ide”  Na 2 S  Sodium and Sulfur  Sodium Sulfide

14. Another Example of Naming Ionic Compounds When Given The Formula Identify the ions in the compound Name the ions in the compound Change the ending on the second element to “ide”  KCl  Potassium and Chlorine  Potassium Chloride

15. Another Example of Naming Ionic Compounds When Given The Formula Identify the ions in the compound Name the ions in the compound Change the ending on the second element to “ide”  CaBr 2  Calcium and Bromine  Calcium Bromide

16. An Example of Naming a Polyatomic Compound Identify the ions in the compounds. Name the ions in the compound (use the polyatomic ion chart). Put the two names together  Li(NO 2 )  Lithium and Nitrite  Lithium Nitrite

17. An Example of Naming a Compound That has a Transition Metal Identify the ions in the compounds. Name the ions in the compound (remember that transition metals have to have a roman numeral in their name). Put the two names together  Ag(Cr 2 O 7 )  Silver (II) and Dichromate **Dichromate has a charge of –2 and it only take one silver to cancel that charge out, silver must be +2  Silver (II) Dichromate

18. Writing a Compound Formula When Given the Name Identify the ions in the formula Write down the symbols and determine the charge using the valence electron trends Put the two ions together (cation goes first) Sodium Nitrate Made up of sodium ion and Nitrate ion Sodium ion is Na + Nitrate ion is NO 3 - Na + and NO 3 - form NaNO 3

19. Another Example of Forming a Compound from a Name Identify the ions in the formula Write down the symbols and determine the charge using the valence electron trends Put the two ions together (cation goes first)  Copper (II) Chloride made up of Copper (II) and Chloride  Copper (II) is Cu 2+ Chloride is Cl -  Cu 2+ and Cl -1 form CuCl 2

20. Forming Covalent Compounds Atoms that share electrons rather than take or give them up are bonded covalently. Neither atom is strong enough to take the electrons from the other. Covalent bonds often happen between two negatively charged ions. Naming covalent molecules is different than naming ionic compounds. Prefixes are used to indicate how many of each atom are in the molecule.