2SBS #9-22, p. 151-152

9) Why are active metals more difficult to process and refine than are less active metals?

Active metals are more reactive than less active metals. Because of this, more active metals are more likely to combine and form compounds with other elements, where as less active metals tend to remain separate.

10) Based on your results from Investigating Matter B.5 (page 142), which metals involved in that investigation would be the easiest to process? Why?

Silver would have been the easiest to process because of its lack of reactivity. Since silver remains separate from other metals and elements, it would be quite easy to process.

11) Why do most metals exist in nature as minerals rather than as pure metallic elements?

Since most metals are more reactive than metals like silver, gold, and platinum, their reactivities tend to make them combine with other elements and form compounds, or minerals.

12) Which of these reactions is more likely to occur? Why? Refer to Table 2.5, page 145.)
a. calcium metal with chromium(III) chloride
b. chromium metal with calcium chloride

a. A reaction between calcium metal with chromium(III) chloride would more likely occur. Calcium metal is more reactive than chromium metal; therefore, putting calcium metal in chromium chloride would create a reaction, where as putting chromium metal in calcium chloride would not form any reaction.

13) Consider the following two equations. Which equation represents a reaction that is more likely to occur? Why?
a. Zn^2+(aq) + 2 Ag(s) ---> Zn(s) + 2 Ag^+(aq)
b. 2 Ag^+(aq) + Zn(s) ---> 2 Ag (s) + Zn^2+(aq)

b. Since zinc is much more reactive than silver, which is barely reactive, putting the metal zinc into a silver solution would cause a reaction; a reaction occurs between a more reactive metal and a less reactive solution.

14)
a. Why would it be a poor idea to stir a solution of lead(II) nitrate with an iron spoon? (Refer to Table 2.5, page 145.)
b. Write a chemical equation to support your answer.

a. Since iron is more reactive than lead, stirring a solution of lead (II) nitrate with an iron spoon would cause a reaction, and the iron spoon would most likely begin to dissolve.
b. Pb^2+(aq) + Fe(s) ---> Pb(s) + Fe^2+(aq)

15) Define oxidation and reduction in terms of electron transfer.

Oxidation is the apparent loss of one or more electrons that causes a metal to become a cation/aqueous solution. Reduction is the apparent gain of one or more electrons that causes a cation/aqueous solution to balance its electrical charge and become a metal.

16) Write an equation for each of the following processes:
a. the reduction of gold(III) ions to gold metal
b. the oxidation of elemental vanadium to vanadium(IV) ions
c. the oxidation of Cu+ to Cu^2+ ions

a. Au^3+ + 3e^- ---> Au
b. V ---> V^4+ + 4e^-
c. Cu+ ---> Cu^2+ + 1e^-

17) Identify each of the following equations as representing either an oxidation reaction or a reduction reaction:
a. Fe^2+ + 2e^- ---> Fe
b. Cr ---> Cr^3+ + 3e^-
c. Al^3+ + 3e^- ---> Al

a. reduction.
b. oxidation.
c. reduction.

18) Consider the following equation:
Zn(s) + Ni^2+(aq) ---> Zn^2+(aq) + Ni(s)
a. Which reactant has been oxidized? Explain your choice.
b. Which reactant has been reduced? Explain your choice.
c. What is the reducing agent in this reaction?

a. Zn^2+ has been oxidized. Zn loses two electrons to become a cation/aqueous solution, Zn^2+.
b. Ni has been reduced. Ni^2+ gains two electrons to essentially rebalance its charge and become a metal/solid as Ni.
c. The reducing agent in this reaction is Zn.

19) Consider the following equation:
2 K(s) + Hg^2+(aq) ---> 2 K^+(aq) + Hg(s)
a. Which reactant has been oxidized? Explain your choice.
b. Which reactant has been reduced? Explain your choice.
c. What is the oxidizing agent in this reaction?

a. K^+ has been oxidized. K loses an electron to become a cation/aqueous solution, K^+.
b. Hg has been reduced. Hg^2+ gains two electrons to essentially rebalance its charge and become a metal/solid as Hg.
c. The oxidizing agent in this reaction is Hg^2+.

20) Write an equation for
a. the oxidation of Al metal by Cr^3+ ions.
b. the reduction of Mn^2+ ions by Mg metal.

a. Al + Cr^3+ ---> Al^3+ + Cr
b. Mn^2+ + Mg ---> Mn + Mg^2+

21) Explain how each of the following processes converts metal cations to metal atoms:
a. electrometallurgy
b. pyrometallurgy
c. hydrometallurgy

a. Electrometallurgy is the use of an electrical current to supply electrons to metal ions, this reducing them.
b. Pyrometallurgy is the treatment of metals and their ores with heat (thermal energy), as in a blast furnace. Carbon (coke) and carbon monoxide are common reducing agents, for they provide electrons, thus reducing the metal ions.
c. Hydrometallurgy is the treatment of ores and other metal-containing materials with reactants in water solution. It is used to recover silver and gold from old mine tailings by a process known as leaching.

22) What processes would be the most useful in obtaining the following elements from their ores?
a. Magnesium.
b. Lead.

a. Electrometallurgy.
b. Pyrometallurgy or find the metal uncombined.

The Acids: Relative Reactivities of Metals Lab

Initial Appearance of the Metals:

Copper: Medium width rectangular strips; bronze and shiny.
Magnesium: Thin rectangular strip; silver and streaky in texture.
Zinc: Larger square strips; silver and shiny.

Procedure:
Before beginning the procedure, we labeled our well plate with the x-axis as each ionic solution, and the y-axis as each metal. Then, we carefully rubbed each metal with steel wool to make them more reactive. After, we put each metal strip in their designated wells and carefully added 10 drops of each ionic solution to each with a beral pipet. We waited a few minutes and observed the reactions of each metal, as recorded below.

Results: Data Table:

Results: Questions: #1-8, page 143:

1. Which metal reacted with the most solutions?

Although both magnesium and zinc showed reactions with copper nitrate and silver nitrate, magnesium’s reaction with copper nitrate was more apparent than zinc’s.

2. Which metal reacted with the fewest solutions?

Copper reacted with the fewest solutions.

3. Assuming that you did not test silver metal, with which solutions (if any) would you expect silver metal to react? Explain your answer, citing evidence from your data and observations.

Although we didn’t test silver due to its high price, going into the experiment we were aware that silver is a very unreactive metal (the reason why it is used in jewelry). Silver would not have reacted with any of the solutions.

4. List the metals (including silver) in order, placing the most reactive metal first (the one reacting with the most solutions) and the least reactive metal last (the one reacting with the fewest solutions).

Magnesium, zinc, copper, silver.

5. Refer to your “metal activity series” list from Question 4. Write a brief explanation of why the outside surface of a penny is made of copper instead of zinc.

Although silver is the least reactive, less than copper, it is too expensive to use on the outside of a penny. Since copper is also an unreactive metal, it is used on the outside of pennies since it will not corrode over time or melt under standard temperatures due to its high melting point.

6. A) Which of the four metals mentioned in this investigation might be an even better choice than copper for the outside surface of a penny? What observational evidence supports your conclusion?

Silver. Silver is the least reactive out of all of the metals.

B) Why do you think that the particular metal that you identified in Question 6a is not used as the outside surface of a penny?

As previously stated, silver is way too expensive to use to make pennies.

7. Given your new knowledge about the relative chemical activities of these four metals,
A) which metal is most likely to be found in an uncombined, or “free,” (metallic) state in nature?

Silver and copper is most likely to be found in an uncombined, or “free” metallic state in nature because they are the least reactive and seldom combine with other substances. This is why copper is used on the surface of pennies and silver (and gold) are used to make jewelry.

B) which metal is least likely to be found chemically uncombined with other elements?

Since magnesium was the most reactive out of the four metals we tested, it is least likely to be found chemically uncombined with other substances in nature. Magnesium combines with other substances very easily due to its high reactivity.

8. Reconsider your experimental design for this investigation:
A) Would it have been possible to eliminate one or more of the metal-solution combinations and still obtain all the information needed to create chemical activity ratings for the four metals?

Yes, it would have been possible to eliminate two of the metal solution combinations and still obtain all of the information needed to create chemical activity ratings for the four metals.

B) If so, which combination or combinations could have been eliminated? Why?

Due to silver’s high price, we eliminated it from our experiment. Since we knew that silver is an unreactive metal, removing it from the test was not a problem. Since we know that zinc is a reactive metal, the reason it is used as the core and not the surface of the penny, we could have removed it from our experiment as well.

Results: Aggregated Data:

2SAS #26-34, p. 132 and 2SBS #1-8, p.151

2SAS:

26) Which are more likely to lose electrons, metallic elements or nonmetallic elements?

Metallic elements form cations; therefore, metallic elements are more likely to lose electrons.

27) Noble gas elements rarely lose or gain electrons. What does this indicate about their chemical reactivity?

Noble gas elements are unreactive and chemically inert.

28) Predict whether each of the following elements would be more likely to form an anion or a cation: (Note: Anions are negatively charged; cations are positively charged.)
a. Na
b. Ca
c. F
d. Cu
e. O
f. Li
g. Sn
h. I

a. cation.
b. cation.
c. anion.
d. cation.
e. anion.
f. cation
g. cation.
h. anion.

29) Which pair is more similar chemically? Defend your choice:
a. copper metal and copper (II) ions
or
b. oxygen with mass number 16 and oxygen with mass number 18

a. copper metal and copper (II) ions: copper metals form cations, and the only difference between copper metal and copper (II) ions is the absence of 2 electrons. Oxygen with mass number 18 as opposed to 16 exhibits an isotope. Neutrons are way bigger than electrons which equal 1/2000 neutrons, so a change in neutrons is a bigger change.

30) The diameter of a magnesium ion (mg^2+) is 156 pm (picometers, where 1 pm = 10^-12 m); the diameter of a strontium ion (Sr^2+) is 254 pm. Estimate the diameter of a calcium ion (Ca^2+).

156+254=410
410/2=205; 205 pm.
The diameter of a calcium ion (Ca^2+) = 205 pm.

31) Three kinds of observations that may indicate a chemical change appear in the following list. However, a physical change may also result in each observation. Describe a possible chemical cause and a possible physical cause for each observation:
a. change in color.
b. change in temperature.
c. formation of a gas.

a.
Chemical cause: oxidization or rusting results in a change in color.
Physical cause: painting a substance results in a change in color.
b.
Chemical cause: combustion causes a change in temperature.
Physical cause: boiling a substance will raise the temperature.
c.
Chemical cause: the reaction of HCl and Cu causes the formation of a gas.
Physical cause: after boiling, water will become a gas (water vapor) as it evaporates.

32) Identify the element that is described by each of the following statements:
a. This element is a nonmetal. It forms anions with a 1- charge. It is in the same period as the metals used in a penny.
b. This element is a metalloid. It is in the same period as the elements found in table salt.

a. Bromine (Br).
b. Silicon (Si).

33) Compare your use of the Snake River data to solve the fish-kill mystery in Unit 1 to Mendeleev's use of element data to create the periodic table.

Mendeleev used atomic weight along with similarities in chemical and physical properties to organize the periodic table. In analyzing our Snake River data to solve the fish-kill mystery in Unit 1, we had to compare mass changes among the different substances we tested for with the normal masses. We used our knowledge of properties of the different substances to create legitimate and logical hypotheses.

34) Mendeleev arranged elements in his periodic table in order of their atomic weights. In the modern periodic table, however, elements are arranged in order of their atomic numbers. Cite two examples from the periodic table for which these two schemes would produce a different ordering of adjacent elements.

Argon (atomic weight: 39.95) would have had to be placed after potassium (atomic weight: 39.10), and cobalt (atomic weight: 58.93) would have had to be placed after nickel (58.69) in order to be accurate in Mendeleev's original periodic table.

2SBS:

1) List two resources typically found in each of the three major "spheres" of Earth.

Atmosphere: nitrogen, oxygen, neon, and argon.
Hydrosphere: water and dissolved minerals.
Lithosphere: petroleum and metal-bearing ores.

2)
a. List and briefly describe three major parts of the lithosphere.
b. Which layer serves as the main storehouse of chemical resources used in manufacturing consumer products?

a.
The crust: top 40km: the thin band of soil and rock containing major raw materials needed to build all manufactured objects.
The mantle: 40-2900km: the middle layer of the lithosphere.
The core: 2900km: Earth's center: extremely hot.
b.
The crust serves as the main storehouse of chemical resources used in manufacturing consumer products.

3) Identify the nation that produces the most
a. silver.
b. copper.
c. tin.

a. Mexico.
b. Japan.
c. China.

4) According to the information in Table 2.3 on page 136, which of these four nations-- the US, Australia, China, or Brazil-- produces the largest masses of the eight listed resources in the table?

China produces the largest masses of the eight listed resources in the table.

5) How do minerals differ from ores?

Ores are naturally occurring rocks or minerals that can be mined and from which are profitable to extract a metal or other metal. Minerals are naturally occurring solid compounds containing the element or group of elements of interest.

6) What factors determine the feasibility of mining a particular metallic ore at a certain cite?

-the quantity of useful ore found at the site.
-the percent of metal in the ore.
-the type of mining and processing needed to extract the metal from its ore.
-the distance between the mine and metal-refining facilities and markets.
-the metal's supply-versus-demand status.
-the environmental impact of the mining and metal processing.

7) A nineteenth-century gold mine, inactive for over 100 years, has recently reopened for further mining. What factors may have influenced the decision to reopen the mine?

Maybe the gold had replenished after 100 years and demand for gold was high.

8) What is meant by referring to the quantity of "useful ore" at a sight.

Useful ore refers to the amount, usually as a percent, of the desired mineral being mined.

Extra Credit for Friday, July 8th: Mental well-being: A New York state: Urban brains behave differently from rural ones of mind:

Mental well-being
A New York state of mind
Urban brains behave differently from rural ones
Jun 23rd 2011 | from the print edition

“HELL is a city much like London,” Percy Bysshe Shelley in 1819.

Building off of Dutch researchers' discovery that city dwellers have a 21% higher risk of developing anxiety disorders and a 39% higher risk of developing mood disorders, Andreas Meyer-Lindenberg of the University of Heidelberg and his colleges used a scanning technique, functional magnetic-resonance imaging (fMRI) to examine the brains of city dwellers and those who live in rural areas under stressful conditions. Dr. Meyer-Lindenberg conducted several experiments; in the first experiment, he had both urban and rural participants of the same general mental healths lay down with their heads in a scanner. The participants were monitored for indications of stress, like high blood pressure, as they took impossible math tests designed for failure while receiving negative feedback through headphones. The brains of the urbanites and country dwellers reacted to the stress very differently in the amygdalas, a pair of structures divided among the two cerebral hemispheres, located deep inside the brain, and responsible for assessing threats and generating fearful emotions, and the perigenual anterior cingulate cortex (pACC), that regulates the amygdalas. In the case of the amygdalas, those who lived in the countryside had the lowest levels of activity in their amygdalas, where as the city dwellers had the highest levels of activity in their amygdalas. Because of the pACC's role in regulating the amygdalas, changes of the pACC may alter the amygdalas, however, the activity and reactions of the pACC are not flexible like the activity of the amygdalas, but are determined during childhood. In other words, a more urban childhood results in a more active pACC, but the activity of the amygdalas reflects where one is currently dwelling. The fMRI measured these correlations between the amygdalas and the pACC. The fMRI reflected the expectations of Dr. Meyer-Lindenberg and his team. The activity of the pACC for the native urbanite showed to be out of kilter. Furthermore, it has been proven that schizophrenia is more common among urbanites than rural dwellers, and that the pACC-amygdala link is quite often out of kilter in schizophrenia; however, Dr. Meyer-Lindenberg is resistent in claiming that his test results show the cause of the out-of-kilter connection. In order to check their results, Dr. Meyer-Lindenberg and his team conducted several subsequent experiments and assigned participants additional stress-free tasks; the subsequent tests matched the results of the original test conducted, and the results of the stress-free tasks showed that the first test was most definitely of social stress, not mental exertion. Therefore, urban brains indeed behave differently than rural ones under stressful situations.

http://www.economist.com/node/18864354

The Acids: Converting Copper Lab

Notes: Procedure:
• Copper powder before the heating is a fine brick-red powder substance
• After the two minutes being on the hot plate, the substance was charcoal and stiff with a slightly purple hue
• Then it was removed from the hot plate and broken up as much as possible with a spatula into a not as fine powder
- Then we placed the crucible back on the hot plate for 10 more minutes with the top ajar to let some oxygen in
• Every two minutes we removed the crucible from the hot plate and broke up the solid with a spatula as previously done
• After the first 2 minutes, it remained a powdery substance with more solid particles
- Instead of having a purplish hue it had a charcoal color
• After the next two minutes the substance remained the same
• After the next two minutes the substance remained the same
• Then we removed the crucible from the hot plate, placed it on the base of the ring-stand, and allowed its contents to cool to room temperature

Questions: Page 140:
1. Answers
a. Describe changes you observed as you heated the copper.
i. We observed color change and the formation of solid particles within the heated crucible. In the first stages of heating, the copper became charcoal in color with a slightly purple hue, and by the end of the heating cycle, the copper was completely charcoal in color.
b. Did the copper atoms remain in the crucible? Explain, using evidence from your observations.
i. Yes the copper did remain inside the crucible but there were slight powder stains on the sides of the crucible that changed color along with the rest of the powder.
2. Answers
a. Were the changes you observed physical changes or chemical changes?
i. As we observed, the copper oxidized; therefore, the changes were chemical changes.
b. What observational evidence leads you to that conclusion?
i. It is a chemical reaction because burning, or combustion, involves chemical reactions between the copper and the oxygen.
3. Answers
a. How did the mass of the crucible contents change after you heated the copper?
i. The mass of the contents did not change at all, they were exactly the same before and after heating
b. Explain why the mass of the crucible contents change in that manner.
i. Although we recognized that the mass of the crucible content should have increased after oxidization, it remained the same. This may be due to crushing the powder too fine, or because of not enough copper particles oxidizing.

Aggregated Data:

Average gain: 0.06g
Median gain: 0.06g

2SAS #13-25, p. 131-132

13) Give another term for each of these features of the periodic table:
a. row.
b. column.

a. A horizontal row is also a period, with elements listed in order of increasing atomic numbers.
b. A vertical column is a group, that contains elements with similar properties.

14) Give the names and symbols of two elements other than lithium in the alkali metal family.

Sodium (Na) and Potassium (K).

15) Consider the noble gas family:
a. Where are noble gases located on the periodic table?
b. Name one physical property that noble gases share.
c. Name one chemical property that noble gases share.

a. The noble gases are located on the far right side of the periodic table.
b. Noble gases are unreactive.
c. Noble gases are chemically inert.

16) Given a periodic table and the formulas BeCl2 and AlN, predict the formula for a compound containing
a. Mg and F.
b. Ga and P.

a. MgF2
b. GaP

17) The melting points of sodium (Na) and rubidium (Rb) are 98°C and 39°C respectively. Estimate the melting point of potassium (K).

Potassium is right between sodium and rubidium on the periodic table:

98+39=137
137/2=68.5

Melting point: 68.5°C.

18) Would you expect the boiling point of chlorine to be higher or lower than that of iodine? Explain.

I would expect the boiling point of chlorine to be lower than that of iodine. From what I have observed, I believe that elements with higher atomic weights have higher boiling points than those with lower atomic weights. Chlorine has a lower atomic weight (35.45) than iodine (126.90), so, chlorine must have a lower boiling point.

19) Copy and complete the following table for each electrically neutral atom.

Completed chart:

20) Using Figure 2.11 (page 121) as a model, illustrate the number of protons, neutrons, and electrons in an atom of
a. beryllium.
b. nitrogen.
c. neon.

a. 4 protons, 4 or 5 neutrons, 4 electrons.
b. 7 protons, 7 or 8 neutrons, 7 electrons.
c. 10 protons, 10 or 11 neutrons, 10 electrons.

21) A student is asked to explain the formation of a lead (II) ion (Pb^2+) from an electrically neutral lead atom (Pb). The student says the a lead atom must have gained two protons to make the ion. How would you correct this student's mistaken explanation?

Although protons are positive, when an atom forms an ion, it either loses or gains electrons. Since a lead ion with a 2+ charge was formed, the atom must have lost two electrons; when electrons are lost, there are more protons remaining in the atom, resulting in the formation of cations, positively charged ions.

22) Refer to the table provided for Question 19:
a. Calculate the mass number for each element in the table.
b. Which element has two isotopes in the table?

a.
Carbon: 6+6=12, or 6+7=13; 12 or 13
Calcium: 20+21=41; 41
Platinum: 78+117=195; 195
Uranium: 92+146=238; 238

b. Carbon has two isotopes in the table.

23) A scientist announces the discovery of a new element. The only characteristic given in the report is the element's mass number of 266. Is this information sufficient, by itself, to justify the claim of the discovery of a new element? Explain.

No, the discovery of a new element would not be justified by only its mass number. It would be more helpful to know either the atomic weight or atomic number in order to be able estimate physical and chemical properties of the element and its probable spot on the periodic table. An element's mass number does not provide enough information to justify its existence.

24) How does the mass of an electron compare to the masses of a proton and a neutron?

The mass of an electron is about 1/2000 the mass of a proton or a neutron. Because of its minuscule weight, it is insignificant, and not used to calculate the mass number of an atom.

25) How many protons and neutrons are needed for each magnesium isotope in this table?

Completed Chart:

Periodic Table and Graphs: Trends in a Chemical Property and Trends in a Physical Property

Questions, Page 123:

1) Does either bar graph reveal a repeating, or cyclic, pattern? Describe any patterns you observe.

By looking at both bar graphs side by side, we noticed that the number of atoms added to the element directly correlated to the boiling points (in °K). The more atoms added, the higher the boiling point.

2) Are these graphs consistent with patterns found in your earlier grouping of the elements? Explain.

Yes. We grouped our elements based on the atom's charge. Elements with positively charged ions were generally on the right side of the table-- closer to what we classified as noble gases. Elements with negatively charged ions were put on the left side of the table, with one positively charged ion set away from the rest of the table on the top. Although the modern periodic table organizes those elements that become cations on the left side of the table, we put the elements that became the cations on the right side of the table, closer to the noble gases, due to the closer atomic numbers and element names (or numbers). Even so, our version of the periodic table sort of imitates the modern periodic table. Additionally, we noticed that positively charged ions generally had higher boiling points than those with negative charges.

3) Based on these two bar graphs, why is the chemist's organization of elements called a periodic table?

Based on these two bar graphs, the chemist's organization of elements is called a periodic table because it is organized in a logical and methodical way, creating patterns that are fairly simple to understand by simply looking at the table.

4) Where are elements with the highest oxide numbers located on the periodic table?

On our periodic table, the elements with the highest oxide numbers are located on the far right and far left of the table (the right side being for the most positively charged ions, and the left side being for the most negatively charged ions).

5) Where are elements with the highest boiling points located on the periodic table?

On our periodic table, the elements with the highest boiling points are located toward the right side of the table. We noticed that the more positive charges the ion had, the higher the boiling point for the element was.

6) Explain any trends you noted in your answers to Question 4 and 5.

The elements with the highest oxide numbers tended to have the highest boiling points.

7) Predict which element should have the lowest boiling point: selenium(Se), bromine(Br), or krypton(Kr). Use evidence from your graphs to explain how you decided.

Bromine should have the lowest boiling point. Out of the three elements, this element is closest to the noble gas (which does not gain any electrons to become an ion), krypton. Bromine has a positive one charge when it is an ion, and selenium has a positive two charge when it is an ion. By analyzing our graph, we noticed that generally, the higher the positive charge, the higher the boiling point of the element; therefore, bromine should have the lowest boiling.

8) Using your graphs, predict the pattern in boiling points and oxide numbers for the next 5 to 8 elements, starting with gallium.

Using our graphs, we believe the higher the oxide numbers, the higher the boiling points will be.