Writing Chemical Formulas and Naming Chemical Compounds

1. Writing Chemical Formulas and Naming Chemical Compounds

2. Lesson #5 – Naming Metal-Non-Metal Compounds • Words for your glossary: • Chemical Formula • Valence • Binary Compound • Zero Sum Rule • Polyatomic Ion

3. The Language of Chemistry http://www.youtube.com/watch?v=q2s8hQ5NIpE&feature=related • It’s like learning a new language • You will learn to take the name of a compound and then find it’s formula Eg. Carbon dioxide = CO2 • You will also learn to translate a formula into words Eg. MgCl2 becomes magnesium chloride. • There are three main patterns: naming ionic compounds, polyatomic ions, and covalent compounds.

4. Chemical Formulas • Provides two important types of information: • 1. ________________________________________________________________ • 2. The number of atoms of each element that are present in a compound. • Tip: __________________________________________________ • Eg. Ca + Br (pp.95 in text)

5. What a chemical formula represents • In covalent compounds: how many of each type of atom are in the molecule • Eg. NH3 • In Ionic compounds: ______________________________________________ • Eg. MgO • Remember that ionic compounds are found in a lattice structure so in MgO, the atoms exist in a 1:1 ratio, held together by ionic bonds.

6. Valence Numbers • Valence: __________________________________________________________________________________________________ • Eg. Group 1 elements have the capacity to lose one e- in order to bond. They have a valence of +1. • Some larger elements have 2 or more valence numbers. Table 3.3, pp. 97.

8. Naming Compounds That Contain a Metal and a Nonmetal • Binary ionic compounds contain ___________ • _____________________________________ • Type I compounds • Metal present forms only one cation • Type II compounds • Metal present can form 2 or more cations with different charges

9. Naming Compounds That Contain a Metal and a Nonmetal

10. Naming Ionic Compounds Type I Binary Ionic compounds

11. Naming Compounds That Contain a Metal and a Nonmetal • For compounds containing both a metal and a nonmetal, ____________________________The nonmetal is named from the root element name.

12. Cations with 2 or more Valences Type II Binary Ionic compounds • Since the metal ion can have more than one charge, a ________________________is used to specify the charge. • Outlined in your text as the Stock System (pp.103, table 3.6)

13. Common multi-valentcations Type II Binary Ionic compounds

14. Polyatomic ions are charged entities composed of several atoms bound together. • They have special names and must be memorized.

15. Polyatomic Ions YOU need to know • Chlorate • Nitrate • Carbonate • Sulfate • Phosphate • Ammonium • Hydroxide

16. Naming ionic compounds containing polyatomic ions follows rules similar to those for binary compounds. • ammonium acetate

17. Polyatomic Ions • ____________________________________ • “poly” means “many” or “lots” in Greek • __________________________________ • Remain unchanged in simple reactions because of _________________________ • They behave like a single unit and should be treated as a ______________________ • The most common is NH4+ - Ammonium • Table 3.4 pp. 98

18. Writing Chemical Formulas Using Valences • Zero Sum Rule: • Eg. KF = the sum of the valences is O • What if you have compound that has multi-valent ions?

19. Cross-Over Rule • Cross Over Rule lets you balance the equations. Pp.99 in your text. • Let’s take Mg – Cl • 1. Write the unbalanced formula (metals first) • 2. Add the valence numbers • 3. Cross over numbers • 4. Check the subscripts (reduce or remove any valences of 1)

21. Practice! • Sodium Sulphide • Aluminum Sulphide • Calcium Oxide • Calcium Phosphide

22. Crossing Over with Polyatomic Ions • Metal + Polyatomic Ion: • Eg. K – PO4 (potassium phosphate) • 1. Write unbalanced formula. Put brackets around the polyatomic ion (s) • 2. Write in the valences • 3. Cross over, write in the subscripts • 4. Tidy up: get rid of 1s, if needed, get rid of the brackets.

23. Poly on Poly • Try Ammonium Phosphate! What about Ammonium Sulphate?

24. Putting it all together • To name a binary compound (2 elements) which is ionic, write the metal first and the non-metal ending in –ide • Eg. Potassium Bromide • If there is an alternate valence, use the stock system when naming the compound. • Eg. Lead (II) oxide (Pb2+ + O) • Conversely, use the cross over rule to find the chemical formula of a compound.

25. One side note….Naming compounds that contain Hydrogen • Can be the first name / least EN • Eg. HCI – Hydrogen chloride • OR can be more EN • Eg. Sodium hydride or lithium hydride. • Many compounds that contain H are acids. We will discuss this later………..

26. Copy the following table and fill in the correct formula or name for each of the compounds listed:

27. Lesson #6 – Naming compounds with polyatomic ions

28. Pattern! • ClO- : hypochlorate • ClO2- : chlorite • ClO3- : chlorate • ClO4- : perchlorate • Can YOU see it?

29. Table 3.7 – Meaning of prefixes and suffixes (pp.105)

30. Really? Yes, Really! • http://www.youtube.com/watch?v=Jp5yblKmQQI&feature=related

31. Practice, Practice, Practice!! • Let’s do #23 on pp. 105 together! • Make sure you do the homework for these two lessons. The only way to be good at this stuff is to do LOTS of examples! • Pp. 19 in your green book! • Make sure you do your readings for lessons 6&7 for Monday!