Transition Elements by Abhishek Jaguessar

8/4/2019 Transition Elements by Abhishek Jaguessar

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The Transition Metals, the

Lanthanides and the Antinides

ByAbhishek Jaguessar


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The Metals in the Middle

Groups 3-12 are called the transitionelements.

All of them are metals.

Transition ElementsTransition Elements

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Across any period from Group 3 through 12,the properties of the elements change lessnoticeably than they do across a period ofrepresentative elements.

Most transition elements are found combinedwith other elements in ores.


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The Iron Triad


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These elements,among others,have magnetic

properties.

Three elements in period 4iron, cobalt, andnickelhave such similar properties that theyare known as

the iron triad.


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The Iron Triad

Industrial magnets are made from an alloyof nickel, cobalt, and aluminum.


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Nickel is used in batteries along withcadmium.

Iron is a necessary part of hemoglobin, thesubstance that transports oxygen in the blood.

Iron also is mixed with other metals and

with carbon to create a variety of steels withdifferent properties.


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Uses of Transition Elements


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Tungsten has the highest melting point of anymetal (3,410C) and will not melt when acurrent passes through it.


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Mercury, which has the lowest melting pointof any metal (39C), is used inthermometers and in barometers.


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Mercury is the only metal that is a liquid at

room temperatures. Like many of the heavy metals, mercury is

poisonous to living beings.


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Chromiumsname comes fromthe Greek word

for color,chrome

.


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Many othertransition elementscombine to formsubstances withbrilliant colors.


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Ruthenium, rhodium, palladium, osmium,iridium, and platinum are sometimescalled the platinum group because they

have similar properties.


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They do not combine as easily with otherelements.

As a result, they can be used as catalysts.


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A catalyst is a substance that can makesomething happen faster but is notchanged itself.


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Other transition elements, such as nickel,zinc, and cobalt, can be used as catalysts.


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Inner Transition Elements

There are two series of inner transition elements.


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The first series, from cerium to lutetium, iscalled the lanthanides.

The second series of elements, from thoriumto lawrencium, is called the actinides.


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The Lanthanides

The lanthanides are soft metals that can becut with a knife.


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The elements are so similar that they are hardto separate when they occur in the same ore,

which they often do. Despite the name rare earth, the lanthanides

are not as rare as originally thought.

Cerium makes up 50 percent of an alloycalled misch (MIHSH) metal. Flints in lighters are made from misch metal.


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The Actinides

All the actinides are radioactive.


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The nuclei of atoms of radioactive elementsare unstable and decay to form other elements.

Thorium, protactinium, and uranium are theonly actinides that now are found naturallyon Earth.

Uranium is found in Earths crust because itshalf-life is long4.5 billion years.


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The Actinides

All other actinides are synthetic elements.


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Synthetic elements are made in laboratoriesand nuclear reactors.

Plutonium is used as a fuel in nuclear powerplants.

Americium is used in some home smokedetectors.

Californium-252 is used to kill cancer cells.


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Dentistry and Dental Materials

Dentists have been using amalgam for over150 years to fill cavities in decayed teeth.


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Amalgam, a mixture of silver, copper, tin,and mercury, is the familiar silver filling.


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Because amalgam contains mercury, somepeople are concerned that the use of thisparticular type of filling may unnecessarily

expose a person to mercury vapor.


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Today dentists have alternatives to amalgam.New composites, resins, and porcelains arebeing used to

repair decayed,broken, ormissing teeth.

S C


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Section CheckSection Check

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Which three elements are known as the iron

triad?

Question 1

The iron triad consists of iron, cobalt, and

nickel. They are called this because of theirsimilar properties.

Answer

S ti Ch k


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Which group consists of ruthenium, rhodium,

palladium, osmium, iridium, and platinum?

Question 2

The answer is the platinum group. These

elements all have similar properties, whichis why they are grouped together.

Answer

S ti Ch k


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What is most notable about the nuclei of the

actinides?

Question 3

The nuclei of actinides are unstable. All the

actinides are radioactive, which means theydecay to form other elements.

Answer

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Transition Elements by Abhishek Jaguessar