Congo, Conflict, Chemistry, and Cans: Day 8
Families on the Periodic Table Part II
I. Transition Metals:
A. Properties:
- Transition metals fall between Groups 4 and 11
- They have an incompletely filled d orbital.
- They are likely to have more than one oxidation
number.
- They react with water slowly, if at all.
B. Checking it out: Calculate the density of three transition metals and observe the reactions of
transition metal salts with a base.
Observing Physical Properties: Transition metals have the same physical properties as other
metals.
i. Observe the pictures of copper, iron, and nickel.
ii. Find density of each metal using a sample of each metal’s mass and volume.
Data:
Physical Properties
Copper
Iron
Nickel
Describe the color.
Describe the luster.
Density =
Mass ÷ Volume
Mass:
81 g
Density:
Volume:
9 mL
Mass:
91 g
Density:
Volume:
11.5 mL
Mass:
85 g
Density:
Volume:
9.6 mL
Questions:
1. Write the transition metals that you tested in order from least dense to most dense.
2. Find copper, iron, and nickel on the periodic table. Did density increase or decrease as you
moved from left to right across the table?
3. Would you expect vanadium to be denser or less dense than iron?
1
Observing Chemical Properties: Transition metals often form colorful salts and are therefore
useful in making dyes and paints. A salt is a compound made of a metal and a non-metal bonded
together.
i. Click on each link to see the chemical reaction when the metal salt solution is combined
with ammonia.
Solution
Color Before
Color After
Ammonia
Ammonia
copper (II) sulfate
https://www.youtube.com/watch?v=jxoHB_sTkI8
Time 0:37 to 0:54
iron (III) chloride
https://www.youtube.com/watch?v=KAeGu88t7KA
Time 1:35 to 1:49
Questions:
1. Is tin a transition metal? How do you know?
2. Could a transition metal be a good replacement for tin in a tin can? Explain.
3. Most transition metals have at least two oxidation states. A copper ion, for example, could be
Cu+ or Cu2+, so copper has two oxidation states. In copper (II) sulfate, the Roman Numeral II
tells us that this copper ion has an oxidation number of 2+.
a) In iron (III) chloride, the iron ion’s oxidation number is ________.
b) In nickel (II) chloride, the nickel ion’s oxidation number is ________.
4. Write the electron configurations (noble gas form) for the following:
Cr:
Ni:
Zr:
5. Based on their electron configuration, how many valence electrons would Cr, Ni, and Zr each
have?
2
II. Quick Review:
Use your periodic table to fill in the chart below.
Isotope
Atomic
Number
Atomic
Mass
14
28
12
Protons
Neutrons
19
21
Electrons
Valence
Number
Oxidation
Number
Metal,
Metalloid, or
Non-metal?
3+
Metalloid
3
Metals as Medicine/ Metals as Poison WS
Stan Jones has blue skin, a side-effect of his preparations for the end of the world. In the
1990’s, many people, including Stan, feared that a programming error would cause all of the
world’s computers to crash when the year changed from ‘99 to ‘00. This “Y2K” apocalypse would
result in looting, riots, and the complete breakdown of society. Stan worried that antibiotics would
suddenly become unavailable, so for the four years leading up to the year 2000, he prepared his
immune system by drinking tubs of water laced with silver ions.
Stan knew that some metals, including silver, have anti-microbial properties. Silver
nanoparticles are routinely used on catheters, clothing, and other products to make them “germfree”. Copper is another metal that kills microbes. It is not a coincidence that all US coins contain
at least a small percentage of copper; no one wants a contagious disease passed on along with their
change. This is also part of the reason that copper is used in pipes, air conditioning ducts, and
stairway handrails.
Mercury is another metal that is toxic to microbes. Unfortunately, it is equally as toxic to the
human body. Before antibiotics, the most popular treatment for syphilis was mercury. Mercury
side effects included loss of hair and teeth, a mouth filled with ulcers, tremors, extreme depression
and insomnia. Often the patient died of mercury poisoning before he would have died of syphilis.
Another medicinal use of mercury was as a laxative. Louis and Clark reportedly took 600 mercury
pills on their trip across the United States. Archaeologists have tracked down some of their
campsites by looking for mercury deposits in the soil. (Antimony was also commonly used as a
laxative. Since it did not dissolve, it could be picked out of the feces and reused.)
Lead was used in creams and ointments for nearly 2,000 years to treat skin infections, skin
cancers, and poison ivy. One fairly recent treatment for diarrhea was a mixture of lead acetate and
opium (a pain killer). The drug worked by poisoning the patient; lead poisoning causes
constipation (thus curing the diarrhea) and a painful stomachache (which the opium dulled).
Being blue didn’t stop Stan Jones from running for governor of Montana (twice) or for US
Senate (twice), but possibly played a part in his losses. He still uses silver as a home remedy. He
says he is in excellent health.
Questions:
1. Which of the metals described in the reading are transition metals? Which are not?
2. What was Stan Jones’ rationale for drinking silver? Does his reasoning make sense to you?
Explain.
3. Why is copper an important addition to coins and handrails?
4. Describe two other “medicinal” uses for metals.
4
Metals as Poison
In 1898, a doctor tried to cure his patients’ night sweats with thallium salts. The thallium
didn’t stop the sweating, but it did cause extreme hair loss. Thallium acetate would be a popular
hair removal treatment for the next 40 years.
The problem with thallium as a medicine is that it only causes hair loss when given at a
near lethal dose. (At a lethal dose, death occurs before hair loss.) In the US, one thallium-based
hair loss product poisoned 692 people and killed 31. Not surprisingly, by the 1930s, thallium was
being phased out as a hair loss treatment.
Thallium confuses the body because it resembles potassium both in size and oxidation
number. (Thallium can have an oxidation number of 1+ or 3+; potassium is 1+.) Cells allow
thallium easy entry through the sodium-potassium pumps in their cell membranes. But thallium is
not chemically identical to potassium and, once inside the cell, it interferes with chemical bonds
and disrupts cell metabolism.
Removing thallium from the body is difficult. The liver can take thallium from the blood
and pass it to the intestines for excretion. But the intestines confuse thallium for potassium and
suck it right back into the bloodstream.
Thallium is colorless, odorless, tasteless, and slow-acting. Poisoning symptoms are very
similar to symptoms of many other illnesses. Therefore, it is very difficult for doctors to recognize
thallium poisoning. Thallium became known as the Poisoner’s Poison because it was easy to buy
as rat poison but hard to detect in victims.
Luckily, an antidote exists. Prussian blue, Fe7(CN)18, is a compound used to make blue
paints and dyes. It has a strong affinity for thallium. When bound to thallium, the resulting
insoluble compound can’t be reabsorbed by the intestines and the thallium can finally be removed
from the body as feces.
Questions:
1. Is thallium a transition metal? How do you know?
2. What was thallium used for in the early 20th century?
3. Why can thallium easily enter human cells?
4. Why is it so difficult to get thallium out of the body?
5. How does Prussian blue work as an antidote to thallium?
5