Welcome to Chem 1A with Terri Bentzinger

1. Welcome to Chem 1Awith Terri Bentzinger Chapter 2 E-mail: benzene4president@gmail.com

2. Atoms – Molecules - Ions – Ch. 2 Drop-In => In addition to CLAS groups you can help and questions answered in CLAS drop-in Writing Drop-In Rm 3231 CLAS Offices Math Physics Engr Drop-in Rm 3263 Econ Drop-in Rm 3255 Class Rooms Chem/Bio Drop-In Rm 3274 Class Rooms

3. Atoms – Molecules - Ions – Ch. 2 Website: http://clas.sa.ucsb.edu/staff/terri/ Google: Terri CLAS Your Syllabus Your CLAS Power Points Additional Useful Information

4. Atoms – Molecules - Ions – Ch. 2 1. For each of the following state if it’s a scientific law, theory or neither: a. As a gas expands under constant pressure the gas will cool. b. The forces between the gas particles are negligible c. On average heavier gas particles will move slower than lighter gas particles d. Gases have a greater average kinetic energy at higher temperatures because the average velocity increases with temperature

5. Atoms – Molecules – Ions – Ch. 2 2. The following data was collected. If it is known that experiment 1 has the formula XY what is the formula of experiment 2.

6. Atoms – Molecules – Ions – Ch. 2 3. (Ch 2 – problem 77) Two elements R and Q, combine to form two binary compounds. In the first compound, 14.0 g of R combines with 3.00 g of Q. In the second compound, 7.00 g of R combines with 4.5 g of Q. Show that these data are in accord with the law of multiple proportions. If the formula of the second compound is RQ, what is the formula of the first?

7. Atoms – Molecules - Ions – Ch. 2 4. What does the following tell you about an atom: a. Atomic number b. Mass number c. Charge

8. Atoms – Molecules - Ions – Ch. 2 Atomic Number (Z) ⇒ # of protons 10 Ne 20.180 Element Symbol Average atomic mass in amu or g/mol Mass Number (A) ⇒ sum of protons and neutrons **Note that mass number is NOT on the periodic table**

9. Atoms – Molecules - Ions – Ch. 2 5. Which of the following represents a pair of isotopes? a. 32S and32S2- b. O2and O3 c. 157N and158O d. 126C and136C e. 188O and199F

10. Atoms – Molecules - Ions – Ch. 2 Isotopes ⇒ atoms of the same element (same number of protons) with varying number of neutrons (different mass number) ex: Chlorine has two naturally occurring isotopes and Atomic Number Z Mass Number A

11. Atoms – Molecules - Ions – Ch. 2 6. Fill in the following table:

12. Atoms – Molecules - Ions – Ch. 2 7. What are ions? How are ions generated?

13. Atoms – Molecules - Ions – Ch. 2 8. Metals tend to gain or lose electrons? What charge do group 1 metals form? What charge do group 2 metals form? What charge do group 3 metals form?

14. Atoms – Molecules - Ions – Ch. 2 Non-metals Metals Metalloids

15. Atoms – Molecules - Ions – Ch. 2 9. Non-metals tend to gain or lose electrons? What charge do group 8 non-metals form? What charge do group 7 non-metals form? What charge do group 6 non-metals form? What charge do group 5 non-metals form?

16. Atoms – Molecules – Ions – Ch. 2 10. How could you distinguish between ionic compounds, covalent compounds and acids?

17. Atoms – Molecules – Ions – Ch. 2 11. Name and label the type of compound for each of the following: a. LiHCO3 g. HClO b. Na2SO3 h. HNO3 c. (NH4)3PO4i. SF6 d. Fe(OH)3 j. CO e. SnO2 k. P2O5 f. HF

18. Atoms – Molecules – Ions – Ch. 2 Naming Ionic Compounds First Name (cation) Second Name (anion) 1. metals with fixed charges (Grps 1,2,3,Ag,Zn and Cd)⇒ use the elements name as is 2. metals with varying charges (all other metals)⇒ use the elements name and a Roman numeral 3. NH4+⇒ ammonium 1. monoatomic ⇒ elements name with the suffix –ide 2. polyatomic ⇒ memorize names (next slide)

19. Atoms – Molecules – Ions – Ch. 2 Common Polyatomic Ions

20. Atoms – Molecules – Ions – Ch. 2 Naming Acids Acids without oxygen Acids with oxygen fox 1. Add prefix hydro to the anion’s name 2. Change suffix to icacid ex: HCN ⇒ hydrocyanic acid or HF ⇒ hydrofluoric acid Change suffix of anion in the acid ate ⇒icacid ite⇒ousacid ex: HNO2⇒ nitrous acid vs. HNO3⇒ nitric acid

21. Atoms – Molecules – Ions – Ch. 2 Naming Covalent/Molecular Compounds 1. Add a Greek prefix to the first element’s name if there’s 2 or more 2. Always add a Greek prefix to the 2nd element and change the suffix to –ide ex: NF3⇒ nitrogen trifluoride

22. Atoms – Molecules – Ions – Ch. 2 12. Write the chemical formulas for the following compounds: a. calcium cyanide b. aluminum sulfate c. lead(IV) oxalate d. hydrosulfuric acid e. sulfuric acid f. phosphorous acid g. sulfur trioxide h. carbon tetrachloride

23. Atoms – Molecules – Ions – Ch. 2 13. Here are some common names that you’re expected to know; write the chemical formula. a. Water b. Methane c. Ammonia

24. Atoms – Molecules – Ions – Ch. 2 14. An element’s most stable ion forms an ionic compound with chlorine having the formula XCl2. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?

25. Atoms – Molecules – Ions – Ch. 2 You have completed ch. 2

26. Ch 2 - Answer Key 1. For each of the following state if it’s a scientific law, theory or neither: a. As a gas expands under constant pressure the gas will cool. Law b. The forces between the gas particles are negligible Theory c. On average heavier gas particles will move slower than lighter gas particles Law d. Gases have a greater average kinetic energy at higher temperatures because the average velocity increases with temperature Theory

27. Ch 2 - Answer Key 2. The following data was collected. If it is known that experiment 1 has the formula XY what is the formula of experiment 2. Set up a ratio of X/Y for each experiment – expt 1 => 2.55gX/12.75g Y = 0.2 where as expt 2 => 1.7 g X/4.25 gY = 0.4 Since expt 2 has a ratio that is twice as much of X then the formula is X2Y

28. Ch 2 - Answer Key 3. (Ch 2 – problem 77) Two elements R and Q, combine to form two binary compounds. In the first compound, 14.0 g of R combines with 3.00 g of Q. In the second compound, 7.00 g of R combines with 4.5 g of Q. Show that these data are in accord with the law of multiple proportions. If the formula of the second compound is RQ, what is the formula of the first? Set up a ratio of R/Q for each experiment – for expt 1 => 14gR/3gQ = 4.67 and for expt 2 => 7gR/4.5gQ = 1.55 since experiment 1 has 3 times more R the formula is R3Q

29. Ch 2 - Answer Key 4. a. Atomic number => # protons in an atom b. Mass number => # protons and # neutrons c. Charge => # protons – # electrons 5. d.Isotopes are atoms of the same element so they have the same number of protons however they differ by the number of neutrons or mass number 6.

30. Ch 2 - Answer Key 7. What are ions? How are ions generated? Ions are charged atoms (monoatomic) or charged groups of atoms (polyatomic) – ions are generated due the gain or loss of electrons producing anions (negative) and cations (positive) 8. Metals tend to gain orlose electrons? What charge do group 1 metals form? 1+ What charge do group 2 metals form? 2+ What charge do group 3 metals form? 3+

31. Ch 2 - Answer Key 9. Non-metals tend to gainor lose electrons? What charge do group 5 non-metals form? 3- What charge do group 6 non-metals form? 2- What charge do group 7 non-metals form? 1- What charge do group 8 non-metals form? No ions

32. Ch 2 - Answer Key 10. How could you distinguish between ionic compounds, covalent compounds and acids? Ionic compounds => cation (typically metal or NH4) and anion (typically nonmetal) Covalent compounds => only nonmetals Acids => covalent compounds that begin with hydrogen (exception => although water is technically an acid it will never be named as such)

33. Ch 2 - Answer Key 11. Name and label the type of compound for each of the following: a. LiHCO3 – lithium bicarbonate or hydrogen carbonate – ionic b. Na2SO3 – sodium sulfite – ionic c. (NH4)3PO4 –ammonium phosphate – ionic d. Fe(OH)3 –iron(III) hydroxide – ionic e. SnO2 – tin(IV) oxide – ionic f. HI – hydroiodic acid – acid g. HClO – hypochlorous acid – acid/molecular h. HNO3 – nitric acid – acid/molecular i. SF6 – sulfur hexafluoride – molecular j. CO – carbon monoxide – molecular k. P2O5 – diphosphoruspentoxide – molecular

34. Ch 2 - Answer Key 12. Write the chemical formulas for the following compounds: a. calcium cyanide – Ca(CN)2 b. aluminum sulfate – Al2(SO4)3 c. lead(IV) oxalate – Pb(C2O4)2 d. hydrosulfuric acid – H2S e. sulfuric acid – H2SO4 f. phosphorous acid – H3PO3 g. sulfur trioxide – SO3 h. carbon tetrachloride – CCl4

35. Ch 2 - Answer Key 13. Here are some common names that you’re expected to know; write the chemical formula. a. Water – H2O b. Methane – CH4 c. Ammonia – NH3 14. An element’s most stable ion forms an ionic compound with chlorine having the formula XCl2. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have? Since Cl has a charge of 1- that tells you that X has a charge of 2+ and if X has 10 electrons there must be 12 protons therefore X is Mg – if the mass number is 24 and there’s 12 protons then there are 12 neutrons