# Welcome to Chem 1A with Terri Bentzinger Chapter 1 & 2 Website:

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Welcome to Chem 1A with Terri Bentzinger Chapter 1 & 2 E-mail: benzene4president@gmail Website: http://clas.sa.ucsb.edu/staff/terri/

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 Chem/Bio Drop-In Rm 3274 Class Rooms

Website: http://clas.sa.ucsb.edu/staff/terri/http://clas.sa.ucsb.edu/staff/terri/ Google: Terri CLAS Your Syllabus Your CLAS Power Points Additional Practice Problems

Atoms – Molecules - Ions – Ch. 1 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

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

Atoms – Molecules – Ions – Ch. 1 3. 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?

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

Atoms – Molecules - Ions – Ch. 2 10 Ne 20.180 Atomic Number (Z) ⇒ # of protons 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**

Atoms – Molecules - Ions – Ch. 2 5. Which of the following represents a pair of isotopes? a. 32 S and 32 S 2- b. O 2 and O 3 c. 15 7 N and 15 8 O d. 12 6 C and 13 6 C e. 18 8 O and 19 9 F

Atoms – Molecules - Ions – Ch. 2 Mass Number A Atomic Number Z

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

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

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?

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

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?

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

Atoms – Molecules – Ions – Ch. 2 11. Name the following compounds: a. LiHCO 3 g. HClO b. Na 2 SO 3 h. HNO 3 c. (NH 4 ) 3 PO 4 i. SF 6 d. Fe(OH) 3 j. CO e. SnO 2 k. P 2 O 5 f. HF

Atoms – Molecules – Ions – Ch. 2 Naming Ionic Compounds First Name (cation) Second Name (anion) 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. NH 4 + ⇒ ammonium 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. NH 4 + ⇒ ammonium 1. monoatomic ⇒ elements name with the suffix –ide 2. polyatomic ⇒ memorize names (next slide) 1. monoatomic ⇒ elements name with the suffix –ide 2. polyatomic ⇒ memorize names (next slide)

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

Atoms – Molecules – Ions – Ch. 2 Naming Acids Acids without oxygen Acids with oxygen fox Naming Acids Acids without oxygen Acids with oxygen fox 1. Add prefix hydro to the anion’s name 2. Change suffix to ic acid ex: HCN ⇒ hydrocyanic acid or HF ⇒ hydrofluoric acid 1. Add prefix hydro to the anion’s name 2. Change suffix to ic acid ex: HCN ⇒ hydrocyanic acid or HF ⇒ hydrofluoric acid Change suffix of anion in the acid ate ⇒ ic acid ite ⇒ ous acid ex: HNO 2 ⇒ nitrous acid vs. HNO 3 ⇒ nitric acid Change suffix of anion in the acid ate ⇒ ic acid ite ⇒ ous acid ex: HNO 2 ⇒ nitrous acid vs. HNO 3 ⇒ nitric acid

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 2 nd element and change the suffix to –ide ex: NF 3 ⇒ nitrogen trifluoride 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 2 nd element and change the suffix to –ide ex: NF 3 ⇒ nitrogen trifluoride

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

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

Atoms – Molecules – Ions – Ch. 2 14. An element’s most stable ion forms an ionic compound with chlorine having the formula XCl 2. 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?

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

Ch 1 - 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

Ch 1 - 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 X 2 Y

Ch 1 - 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 R 3 Q

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. Isotope SymbolProtonsNeutronsElectronsCharge 47 Ti222522none 90 Sr 2+ 3852362+ 37 Cl – 1720181–

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 or lose 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+

Ch 2 - Answer Key 9. Non-metals tend to gain or 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

Ch 2 - Answer Key 10. How could you distinguish between ionic compounds, covalent compounds and acids? Ionic compounds => cation (typically metal or NH 4 ) 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)

Ch 2 - Answer Key 11. Name and label the type of compound for each of the following: a. LiHCO 3 – lithium bicarbonate or hydrogen carbonate – ionic b. Na 2 SO 3 – sodium sulfite – ionic c. (NH 4 ) 3 PO 4 – ammonium phosphate – ionic d. Fe(OH) 3 – iron(III) hydroxide – ionic e. SnO 2 – tin(IV) oxide – ionic f. HI – hydroiodic acid – acid g. HClO –hypochlorous acid – acid/molecular h. HNO 3 – nitric acid – acid/molecular i. SF 6 – sulfur hexafluoride – molecular j. CO – carbon monoxide – molecular k. P 2 O 5 – diphosphorus pentoxide – molecular

Ch 2 - Answer Key 12. Write the chemical formulas for the following compounds: a. calcium cyanide – Ca(CN) 2 b. aluminum sulfate – Al 2 (SO 4 ) 3 c. lead(IV) oxalate – Pb(C 2 O 4 ) 2 d. hydrosulfuric acid – H 2 S e. sulfuric acid – H 2 SO 4 f. phosphorous acid – H 3 PO 3 g. sulfur trioxide – SO 3 h. carbon tetrachloride – CCl 4

Ch 2 - Answer Key 13. Here are some common names that you’re expected to know; write the chemical formula. a. Water – H 2 O b. Methane – CH 4 c. Ammonia – NH 3 14. An element’s most stable ion forms an ionic compound with chlorine having the formula XCl 2. 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

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