7/26/2019 450 Actinides (1).pdf

1/43

Actinides

The 5f series elements

7/26/2019 450 Actinides (1).pdf

2/43

The group also known as Heavier

elements or inner series transition

elements following actinium from Ac to Lr.

Actinides series elements of which

uranium( U, 92) and plutonium( Pu, 94)

are best known are built up by completion

of the 5f orbitals.

7/26/2019 450 Actinides (1).pdf

3/43

7/26/2019 450 Actinides (1).pdf

4/43

7/26/2019 450 Actinides (1).pdf

5/43

Trans-uranium elements

For a very long time U (92) continued to

be the last heavy element known

After 1940 a series of 11 elements with Z

93-103 were identified and synthesized by

transformation of naturally occurring

elements by nuclear reactions.

These man made elements are called

trans-uranium elements

7/26/2019 450 Actinides (1).pdf

6/43

Actinium

A soft, silvery metal, which is reported to

glow blue. This is due to its radioactivity.

Actinium starts the series of actinoids

(elements 90-103), which are named after

this element. It naturally occurs from

uraniumdecay, the half-life of its most

stable isotope is less than 22 years. It hasvery few applications, because it is difficult

to handle and very dangerous.

http://images-of-elements.com/actinoids.phphttp://images-of-elements.com/uranium.phphttp://images-of-elements.com/uranium.phphttp://images-of-elements.com/actinoids.php

7/26/2019 450 Actinides (1).pdf

7/43

Chemically, it is similar to lanthanum. Most

actinium decays to thorium, about 1.4% to

francium.

http://images-of-elements.com/lanthanum.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/francium.phphttp://images-of-elements.com/francium.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/lanthanum.php

7/26/2019 450 Actinides (1).pdf

8/43

Thorium

Thorium by far is the most stable and frequent

actinoid, the half-life of 232Th is 14 billion years.

The soft, in pure form silvery metal is chemically

very reactive and only light toxic. However, its weak radioactivity can become

dangerous, if it is inhaled. Therefore it is not

longer much used for mantles in gas lights,

unlike years ago. It is still common for some

special alloys and in good camera lenses (as

ThO2). Thorium decays to radium.

http://images-of-elements.com/actinoids.phphttp://images-of-elements.com/radium.phphttp://images-of-elements.com/radium.phphttp://images-of-elements.com/actinoids.php

7/26/2019 450 Actinides (1).pdf

9/43

Thorium

7/26/2019 450 Actinides (1).pdf

10/43

Protactinium

A compact chunk of the radioactive heavy

metal produces so much heat that it glows

red.

no stable isotopes

Protactinium primarly is generated from

the decay of the rare isotope uranium235

(via the very unstable thorium231).

Therefore it only exists in small amounts,

most of it is found in nuclear waste.

http://images-of-elements.com/uranium.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/uranium.php

7/26/2019 450 Actinides (1).pdf

11/43

The half-life of the most stable isotope is

32,760 years, which makes the highly

toxic element even in tiny amounts very

dangerous for a long time.

Outside of science, no reasonable

applications for protactinium exist.

Nearly all protactinium decays further to

actinium.

http://images-of-elements.com/actinium.phphttp://images-of-elements.com/actinium.php

7/26/2019 450 Actinides (1).pdf

12/43

Uranium

7/26/2019 450 Actinides (1).pdf

13/43

Uranium is a chemically very reactive,

grey heavy metal. Like all actinoidsit is

radioactive, after thoriumit is the second

most stable of those. The most abundantnatural isotope is 238U with a half-life of 4.5

billion years. The basis for nuclear power

plants is the fissile isotope 235U. Thefission products often are highly

radioactive isotopes of lower elements,

like Cs137 and Sr 90.

http://images-of-elements.com/actinoids.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/thorium.phphttp://images-of-elements.com/actinoids.php

7/26/2019 450 Actinides (1).pdf

14/43

Uranium 235 is used for atomic bombs,

too, like the one in Hiroshima.

It has a natural abundance of only 0.7 %

and has to be enriched in an extensive

process.

For power plants, at least 3 % are needed,

for weapons much more.

7/26/2019 450 Actinides (1).pdf

15/43

The waste material of this process,

depleted uranium, sometimes is used in

ammunition, sometimes is turned into

plutoniumin a breeder reactor, but most ofit is just thrown away.

Natural uranium decays to thorium.

http://images-of-elements.com/plutonium.phphttp://images-of-elements.com/plutonium.php

7/26/2019 450 Actinides (1).pdf

16/43

Neptunium

Los Alamos National Laboratory, 2002

6 kg heavy neptunium 237 sphere.

7/26/2019 450 Actinides (1).pdf

17/43

Neptunium, a radioactive, silver heavy

metal, is quite stable for an element with a

high and odd atomic number, 237Np has a

half-life of 2 million years.

On Earth, it naturally occurs in tiny traces

in uraniumore, but it is found in much

bigger amounts in nuclear waste.

http://images-of-elements.com/uranium.phphttp://images-of-elements.com/uranium.php

7/26/2019 450 Actinides (1).pdf

18/43

So far it is scarcely used, although it is

fissionable.

Like with every nuclear waste, there is no

method of a reasonable disposal. Most of

it decays to protactinium.

http://images-of-elements.com/protactinium.phphttp://images-of-elements.com/protactinium.php

7/26/2019 450 Actinides (1).pdf

19/43

Plutonium

7/26/2019 450 Actinides (1).pdf

20/43

Plutonium, a silvery, very heavy and hard

metal, is perhaps the most dangerous of

all elements and the one that, relative to

its amount, did the worst damages tohumanity and environment.

It was in the bomb of Nagasaki and,

together with uranium, involved in theChernobyl disaster. In multiple nuclear

tests it devastated huge areas.

http://images-of-elements.com/uranium.phphttp://images-of-elements.com/uranium.php

7/26/2019 450 Actinides (1).pdf

21/43

It is still used in nuclear power plants,

where it produces waste that cannot be

depolluted, can be made weapons-grade

and is a constant threat for the entireworld.

In nature, plutonium only occurs in very

small amounts, all that is in use isartificially made from uranium.

7/26/2019 450 Actinides (1).pdf

22/43

Apart from its radioactivity, it is very toxic.

As fissile material, commonly 239Pu is

used.

When hit by a neutron, this decays and

releases more neutrons and radioactive

waste.

If not fissioned, most plutonium decays to

uranium.

http://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/particle-zoo/neutron.php

7/26/2019 450 Actinides (1).pdf

23/43

Americium

1944: the first produced americium (as

hydroxide) on the bottom of a glass vial.

7/26/2019 450 Actinides (1).pdf

24/43

Americium is the first synthetic element,

from here onwards all elements have to be

produced in laboratories.

These are very radioactive.

The most stable isotope of americium,243Am, has a half-life of just under 7400

years.

7/26/2019 450 Actinides (1).pdf

25/43

Due to its strong alpha radiation,

americium is very dangerous.

In some countries americium 241 (432

years half life) is used in tiny amounts in

smoke detectors for ionizing air.

Americium emerges in small amounts in

nuclear reactors from plutoniumand

mostly decays to neptunium.

http://images-of-elements.com/plutonium.phphttp://images-of-elements.com/neptunium.phphttp://images-of-elements.com/neptunium.phphttp://images-of-elements.com/plutonium.php

7/26/2019 450 Actinides (1).pdf

26/43

Curium

Chemically similar to gadolinium, but

highly radioactive, the metal produces

much heat.

The synthetic element curium is usually

made from plutoniumand mostly decays

to this again. The most stable isotope,

247Cm, has a quite long half-life of 15.6million years. However, this is scarcely

produced.

http://images-of-elements.com/gadolinium.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/gadolinium.php

7/26/2019 450 Actinides (1).pdf

27/43

Much more frequent are the significantly more

unstable isotopes 242 and 244, which emit very

intense radiation. Therefore, the enormously

dangerous curium is used only rarely and in safeenvironments, like in space missions.

The Mars rovers had it with them in their X-ray

spectrometers. Long and short lived curium

isotopes are also produced unintentionally inatomic reactors and then end up in nuclear

waste.

7/26/2019 450 Actinides (1).pdf

28/43

Berkelium

The highly reactive, silvery metal is a

strong -emitter.

Berkelium is made from americiumor

curium, mostly unintentional, because

outside of basic research it hasn't any

application. The most stable isotope,

247Bk, has a half-life of 1380 years, but thisis hardly produced.

http://images-of-elements.com/americium.phphttp://images-of-elements.com/curium.phphttp://images-of-elements.com/curium.phphttp://images-of-elements.com/americium.php

7/26/2019 450 Actinides (1).pdf

29/43

The most commonly accrued 249Bk has a

half-life of only 330 days. Of this, each

year about 1 gram emerges worldwide as

waste in nuclear reactors, most of itdecays to californium.

http://images-of-elements.com/californium.phphttp://images-of-elements.com/californium.php

7/26/2019 450 Actinides (1).pdf

30/43

Californium

The strong and neutronemitter produces

a considerable heat. Californium emerges in tiny amounts

rather randomly from plutoniumvia the

elements between these two. With Californium, it is a bother to

laboriously extract it, because for 252Cf,

which has a half-life of 2.6 years. About 3% of this isotope spontaneously

fissions into large chunks and hot

neutrons.

http://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/particle-zoo/neutron.php

7/26/2019 450 Actinides (1).pdf

31/43

Therefore it is used as a strong neutron

source, for example in detectors for metalfatigue and in medicine for very intense

irradiation. The enrichment of californium

252 is very expensive, each year onlyabout 0.1 grams are made. When used,

strict safety regulations have to be

complied, although in each case only

some micrograms of it are involved. The

isotope 251Cf has a half-life of 900 years.

Most californium decays to curium.

http://images-of-elements.com/curium.phphttp://images-of-elements.com/curium.php

7/26/2019 450 Actinides (1).pdf

32/43

Einsteinium and Fermium

Einsteinium and fermiumare produced insmall amounts in the biggest man-made

explosions, those of hydrogenbombs,

from the igniter plutoniumand neutrons

that are flying around. Einsteinium alsocan be made in labs, however the highly

radioactive metal has no use outside of

basic research.

http://images-of-elements.com/fermium.phphttp://images-of-elements.com/hydrogen.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/plutonium.phphttp://images-of-elements.com/hydrogen.phphttp://images-of-elements.com/fermium.php

7/26/2019 450 Actinides (1).pdf

33/43

The most stable isotope has a half-life of

472 days. Einsteinium of course was

named after Albert Einstein, who himself

had no connection to the element.Einsteinium decays to berkeliumor

californium.

http://images-of-elements.com/berkelium.phphttp://images-of-elements.com/californium.phphttp://images-of-elements.com/californium.phphttp://images-of-elements.com/berkelium.php

7/26/2019 450 Actinides (1).pdf

34/43

Mendelevium

Chemically similar to Thulium, the highly

radioactive heavy metal emits very

energetic -radiation.

Mendelevium is the first synthetic element,

which can't be produced any more by

neutroncapture. To make mendelevium,

einsteiniumis bombarded with heliumnuclei. Most of it decays to einsteinium

again.

http://images-of-elements.com/thulium.phphttp://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/einsteinium.phphttp://images-of-elements.com/helium.phphttp://images-of-elements.com/helium.phphttp://images-of-elements.com/einsteinium.phphttp://images-of-elements.com/particle-zoo/neutron.phphttp://images-of-elements.com/thulium.php

7/26/2019 450 Actinides (1).pdf

35/43

The most stable mendelevium isotope has

a half-life of 52 days.

The element is named to honor Dmitri

Mendeleev, the developer of the periodic

table of elements.

7/26/2019 450 Actinides (1).pdf

36/43

Nobelium

Nobelium can only be made in very smallamounts and emits strong radiation of

various kinds.

Nobelium is produced for example bybombarding californiumwith carbonor

uraniumwith neon. The most stable

isotope has a half-life of 58 minutes. Most

of it decays to fermiumor by spontaneous

fission. Of its physical properties not much

is known, but they are probably similar to

those of the other actinoids.

http://images-of-elements.com/californium.phphttp://images-of-elements.com/carbon.phphttp://images-of-elements.com/uranium.phphttp://images-of-elements.com/neon.phphttp://images-of-elements.com/fermium.phphttp://images-of-elements.com/actinoids.phphttp://images-of-elements.com/actinoids.phphttp://images-of-elements.com/fermium.phphttp://images-of-elements.com/neon.phphttp://images-of-elements.com/uranium.phphttp://images-of-elements.com/carbon.phphttp://images-of-elements.com/californium.php

7/26/2019 450 Actinides (1).pdf

37/43

Lawrencium

Lawrencium can only be made in very

small amoun

Lawrencium is produced for example by

bombarding californiumwith boronor

americiumwith oxygen.

The most stable isotope has a half-life of

3.6 hours.

This decays to nobelium, most other

isotopes to mendelevium.

http://images-of-elements.com/californium.phphttp://images-of-elements.com/boron.phphttp://images-of-elements.com/americium.phphttp://images-of-elements.com/oxygen.phphttp://images-of-elements.com/nobelium.phphttp://images-of-elements.com/mendelevium.phphttp://images-of-elements.com/mendelevium.phphttp://images-of-elements.com/nobelium.phphttp://images-of-elements.com/oxygen.phphttp://images-of-elements.com/americium.phphttp://images-of-elements.com/boron.phphttp://images-of-elements.com/californium.php

7/26/2019 450 Actinides (1).pdf

38/43

Of its physical properties not much is

known, but they are probably similar to

those of the other actinoids.

Lawrencium could be the hardest and

heaviest of them.

It emits strong radiation.

http://images-of-elements.com/actinoids.phphttp://images-of-elements.com/actinoids.php

7/26/2019 450 Actinides (1).pdf

39/43

Separation of Plutonium (Pu) from Uranium (U)

(Redox Process using Hexone)

UO22++ Pu4+ + Fission Products (FPs)

UO22++ PuO2

2++ FPs

aq. Phase org phase

FPs UO22++ PuO2

2+

Org.phase aq. Phase

UO22+ Pu4+

Org.phase aq. Phase Repeat oxidation

recycle and extraction cycle

Oxidize by K2Cr2O7

Add Al(NO3)3Extract with hexone

Was with SO2

Dil. HNO3

7/26/2019 450 Actinides (1).pdf

40/43

Separation of Plutonium (Pu) from Uranium (U)

(Co-precipitation method using BiPO4)

UO22++ Pu6+ + Fission Products (FPs)

UO22++ Pu4++ FPs

Residue Filtrate

BiPO4carrying Pu4+ UO2

2+

PuO22-+ Bi3++ FPs

PO4-3

(i) Add H2SO4to prevent ppt of U6+

(ii) Add BiPO4

Dissolve in HNO3and oxidize Pu4+to

Pu6+with KMnO4, K2Cr2O7

Residue

BiPO4carrying FPs

Filtrate

Pu6+

NO2-

7/26/2019 450 Actinides (1).pdf

41/43

7/26/2019 450 Actinides (1).pdf

42/43

7/26/2019 450 Actinides (1).pdf

43/43