Gallium

1871
Dmitrii Ivanovich Mendelev predicts the existance and properties of the element
after zinc in the periodic table. He Gives it the name "eka aluminium".

1875
Paul Emile Lecoq de Boisbaudran discovers gallium.
Its properties closely match those predicted by Mendelev.


Gallium, atomic number 31, is very similar to aluminum in its chemical
properties. It does not dissolve in nitric acid because of the protective film of
gallium oxide that is formed over the surface by the action of the acid. Gallium
does however dissolve in other acids, and alkalies.

Gallium was discovered (1875) by Paul Emile Lecoq de Boisbaudran, who observed
its principal spectral lines while examining material seperated from zinc blende.
Soon after he isolated the metal studied its properties, which coincided those that
Dmitrii Ivanovich Mendelev had predicted a few years earlier for eka-aluminium, the
then undiscovered element lying between aluminum and indium in his periodic table.

Though widely distributed at the Earth's surface, gallium does not occor
free or concentrated in independant minerals, except for gallite. It is extracted as
a by-product from zinc blende, iron pyrites, bauxite, and germanite.

Silvery white and soft enough to be cut with a knife, gallium takes on a bluish
tinge because of superficial oxidation. Unusual for its low melting point
( about 30 degrees C, 86 degrees F ), gallium also expands upon solidification and
supercools readily, remaining a liquid at temperatures as low as 0 degrees C ( 32 degrees F ).

Gallium has the longest usefull liquid range of any element. The liquid metal
clings to glass and similar surfaces. The crystal structure of gallium is orthorhombic.
Natural gallium consists of a mixture of two stable isotopes: gallium-69 ( 60.4 percent )
and gallium-71 (39.6 percent ).

Somewhat similar to aluminum chemically, gallium slowly oxidizes in moist air
until a protective film forms, and it becomes passive in cold nitric acid.

Gallium has been considered as a possible heat-exchange medium in nuclear reactors,
although it has a high neutron cross section. Radioactive gallium-72 shows some promise
in the study of bone cancer; a compound of this isotope is absorbed by the cancerous
portion of the bone.

The most common use of gallium is in a gallium scan. Gallium scans are often used
to diagnose and follow the progression of tumors or infections. Gallium scans can also be
used to evaluate the heart, lungs, or any other organ that may be involved with inflammatory
disease.

A gallium scan usually requires two visits to the Nuclear Medicine Department.
On the first day you recieve an injection in a vein in your arm, you will then be scheduled
to return beetween 2 and 5 days later, depending on your diagnosis. Your initial scan can
take several hours, while you lay on a stretcher, or imaging table, and a camera is positioned
above you or below you, taking pictures as it moves slowely along the length of your body.
No special preperation must be taken before the scan, and the gallium is usually excreted
through the bowel.

drinking and driving offenses

"DRINKING AND DRIVING OFFENCES" My essay is on "Drinking and Driving Offences". In my essay I will tell you the various kinds of drinking and driving offences, the penalties,and the defences you can make if you are caught drinking and driving. Let me tell you about the different offences. There are six offences in drinking and driving. They are "driving while impaired", "Having care and control of a vehicle while impaired", "Driving while exceeding 80 m.g.", "Having care and control of a vehicle while exceeding 80 m.g.", "Refusing to give a breath sample", and "refusing to submit to a roadside screen test. These are all Criminal Code Offences. Now lets talk about the penalties of drinking and driving. The sentence for "refusing to give a breath sample" is usually higher than either of the "exceeding 80 m.g." offences. Consequently it is usually easier in the long run for you to give a breath sample if asked. If, for example you are convicted of "Refusing ato give a breath sample" for the first time, but was earlier convicted of "Driving while impaired", your conviction for "Refusing" will count as a second conviction, not a first,and will receive the stiffer penalty for second offences. For the first offence here is the penalty and the defences you can make. Driving a vehicle while your ability to drive is impaired by alcohol or drugs is one of the offences. Evidence of your condition can be used to convict you. This can include evidence of your general conduct, speech, ability to walk a straight line or pick up objects. The penalty of the first offences is a fine of $50.00 to $2000.00 and/or imprisonment of up to six months, and automatic suspension of licence for 3 months. The second offence penalty is imprisonment for 14 days to 1 year and automatic suspension of licence for 6 months. The third offence penalty is imprisonment 2 or 3 months to 2 years (or more) and automatic suspension of licence for six months. These penalties are the same for the following offences. "Having Care and Control of a Motor Vehicle while Impaired" is another offence. Having care and control of a vehicle does not require that you be driving it. Occupying the driver's seat, even if you did not have the keys, is sufficient. Walking towards the car with the keys could be suffi- cient. Some defences are you were not impaired, or you did not have care and control because you were not in the driver's seat, did not have the keys,etc. It is not a defence that you registered below 80 m.g. on the breath-

ayzer test. Having care and control depends on all circumstances. "Driving While Exceeding 80 m.g. is the next offence. Driving a vehicle, having consumed alcohol in such a quantity that the proportion of alcohol in your blood exceeds 80 miligrams of alcohol in 100 mililitres of blood. Some defences are the test was administered improperly, or

discovery of the electron

The Discovery Of The Electron

The electron was discovered in 1895 by J.J. Thomson in the
form of cathode rays, and was the first elementary particle to be
identified. The electron is the lightest known particle which
possesses an electric charge. Its rest mass is Me <approximately
equal> 9.1 x 10 -28 g, about 1/1836 of the mass of the proton or
neutron.

The charge of the electron is -e = -4.8 x 10^-10 esu <elec
trostatic unit). The sign of the electron's charge is negative by
convention, and that of the equally charged proton is positive.
This is somewhat a unfortunate convention, because the flow of
electrons in a conductor is opposite to the conventional direc
tion of the current.

The most accurate direct measurement of e is the oil drop
experiment conducted by R.A. Milikan in 1909. In this experiment,
the charges of droplets of oil in air are measured by finding the
electric field which balances each drop against its weight. The
weight of each drop is determined by observing its rate of free
fall through the air, and using Stokes' formula for the viscous
drag on a slowly moving sphere. The charges thus measured are
integral multiples of e.

Electrons are emitted in radioactivity <as beta rays> and in
many other decay processes. The electron itself is completely
stable. Electrons contribute the bulk to ordinary matter; the
volume of an atom is nearly all occupied by the cloud of elec
trons surrounding the nucleus, which occupies only about 10^-13
of the atom's volume. The chemical properties of ordinary matter are
determined by the electron cloud.

The electron obeys the Fermi-Dirac statistics, and for this
reason is often called a fermion. One of the primary attributes
of matter, impenetrability, results from the fact that the elec
tron, being a fermion, obeys the Pauli exclusion principle.

The electron is the lightest of a family of elementary
particles, the leptons. The other known charged leptons are the
muon and the tau. These three particles differ only in mass;
they have the same spin, charge, strong interactions, and weak
interactions. In a weak interaction a charged lepton is either
unchanged or changed into and uncharged lepton, that is a neutri
no. In the latter case, each charged lepton is seen to change
only into the corresponding neutrino.

The electron has magnetic properties by virtue of (1) its
orbital motion about the nucleus of its parent atom and (2) its
rotation about its own axis. The magnetic properties are best
described through the magnetic dipole movement associated with 1
and 2. The classical analog of the orbital magnetic dipole moment
of a small current-carrying circuit. The electron spin magnetic
dipole moment may be thought of as arising from the circulation
of charge, that is, a current, about the electron axis; but a
classical analog to this moment has much less meaning than that
to the orbital magnetic dipole moment. The magnetic moments of
the electrons in the atoms that make up a solid give rise to the
bulk magnetism of the solid.