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awfulhihatUrban and Civil

Nov 15, 2013 (3 years and 4 months ago)

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Hydrogen


Hydrogen

(


haɪdrɵdʒɨn
/

HY
-
drə
-
jin
)
[4]

is the

chemical
element

with

atomic number

1.
It is represented by
the

symbol

H. With an
average

atomic
weight

of

1.00794

u

(1.007825

u

for

Hydrogen
-
1
), hydrogen is
the lightest and

most
abundant

chemical element,
constituting roughly 75% of the
Universe's chemical elemental
mass.
[5]

Stars

in the

main
sequence

are mainly
composed of hydrogen in
its

plasma

state. Naturally
occurring elemental hydrogen
is relatively rare on Earth.

Copper


Copper

(


kɒpər
/

KOP
-
ər
) is a

chemical
element

with the symbol

Cu

(from

Latin
:

cuprum
)
and

atomic number

29. It is a

ductile

metal with
very high

thermal

and

electrical conductivity
. Pure
copper is soft and malleable; an exposed surface
has a reddish
-
orange tarnish. It is used as a
conductor of heat and electricity, a building
material, and a constituent of various metal

alloys
.


The metal and

its alloys

have been used for
thousands of years. In the Roman era, copper was
principally mined on

Cyprus
, hence the origin of
the name of the metal as

сyprium

(metal of
Cyprus), later shortened to

сuprum
. Its
compounds are commonly encountered as
copper(II) salts, which often impart blue or green
colors

to minerals such as

turquoise

and have
been widely used historically as pigments.
Architectural structures built with copper corrode
to give green

verdigris

(or

patina
).

Decorative
art

prominently features copper, both by itself and
as part of pigments.


Copper(II) ions are water
-
soluble, where they
function at low concentration as

bacteriostatic

substances
,

fungicides
, and wood preservatives.
In sufficient amounts, they are poisonous to
higher organisms; at lower concentrations it is an
essential trace

nutrient

to all

higher plant

and
animal life. The main areas where copper is found
in animals are tissues, liver, muscle and bone.


Ununpentium


Ununpentium

is the temporary
name of a

synthetic

superheavy

element

in the

periodic table

that
has the temporary
symbol

Uup

and has the

atomic
number

115.


It is placed as the heaviest
member of group 15 (VA)
although a sufficiently stable
isotope is not known at this time
that would allow chemical
experiments to confirm its
position. It was first observed in
2003 and only about 30 atoms of
ununpentium

have been
synthesized to date, with just 4
direct decays of the parent
element having been detected.
Four consecutive isotopes are
currently known,

287

290
Uup,
with

289
Uup having the longest
measured

half
-
life

of ~220
ms.
[1]


Helium


Helium

(


hiːliəm
/

HEE
-
lee
-
əm
) is the

chemical
element

with

atomic number

2 and an atomic
weight of 4.002602, which is represented by
the

symbol

He. It is a
colorless
,
odorless
,
tasteless, non
-
toxic,

inert
,

monatomic

gas

that
heads the

noble gas

group in the

periodic table
.
Its

boiling

and

melting

points are the lowest
among the elements and it exists only as a gas
except in extreme conditions. Next to

hydrogen
,
it is the second most

abundant element

in the
universe and accounts for 24% of the elemental
mass of our galaxy.


An unknown yellow

spectral line

signature in sunlight
was first observed during a

solar eclipse in 1868

by
French astronomer

Jules Janssen
. Janssen is jointly
credited with the

discovery of the
element

with

Norman
Lockyer
, who observed the
same eclipse and was the first to propose that the line
was due to a new element, which he named helium. In
1903, large reserves of helium were found in

natural
gas fields

in parts of the United States, which is by far
the largest supplier of the gas.


Helium is used in

cryogenics

(its largest single use,
absorbing about a quarter of production), particularly
in the cooling of

superconducting magnets
, with the
main commercial application being
in
MRI

scanners.
Helium's other industrial uses
-

as a pressurizing and
purge gas, as a protective atmosphere for

arc
welding

and in processes such as growing crystals to
make

silicon wafers
-

account for half of the gas
produced. A well
-
known but minor use is as a lifting
gas in balloons and

airships
.
[2]

As with any gas with
differing density from air, inhaling a small volume of
helium temporarily changes the timbre and quality of
the human voice. In scientific research, the
behavior

of
the two fluid phases of helium
-
4 (helium

I and
helium

II), is important to researchers
studying
quantum

mechanics

(in particular the property
of

superfluidity
) and to those looking at the
phenomena, such as

superconductivity
, that
temperatures near

absolute zero

produce in

matter
.
Helium is the second lightest element and is the
second most

abundant

in the observable

universe
,
being present in the universe in masses more than 12
times those of all the heavier elements combined. Its
abundance is similar to this figure in our own

Sun

and
in

Jupiter
. This is due to the very high binding energy
(per

nucleon
) of helium
-
4 with respect to the next
three elements after helium (
lithium
,

beryllium
,
and

boron
). This helium
-
4 binding energy also
accounts for its commonality as a product in both
nuclear fusion and radioactive decay. Most helium in
the universe is helium
-
4, and is believed to have been
formed during the

Big Bang
. Some new helium is
being created currently as a result of the

nuclear
fusion

of hydrogen in stars greater than 0.5 solar
masses.


On Earth, the lightness of helium has caused its
evaporation from the gas and dust cloud from which
the planet condensed,
[
citation needed
]

and it is thus
relatively rare

0.00052% by volume in the
atmosphere. Most terrestrial helium present today is
created by the natural

radioactive decay

of heavy
radioactive elements (
thorium

and

uranium
), as
the

alpha particles

emitted by such decays consist of
helium
-
4

nuclei
. This

radiogenic

helium is trapped
with

natural gas

in concentrations up to 7% by volume,
from which it is extracted commercially by a low
-
temperature separation process called

fractional
distillation
.


Potassium


Potassium

(

/
pɵˈtæsiəm
/

po
-
TAS
-
ee
-
əm
) is the

chemical
element

with the symbol

K

(from

Neo
-
Latin

kalium
) and

atomic
number

19. Elemental potassium is a soft silvery
-
white

alkali
metal

that
oxidizes

rapidly in

air

and is very reactive with

water
,
generating sufficient heat to ignite the hydrogen emitted in the
reaction.


Potassium and

sodium

are alkali metals and are

chemically

very
similar. For this reason it took a long time before their salts were
differentiated. They were suspected to be different elements within
their salts after 1702, and this was proven in 1807 when potassium
and sodium were individually isolated from different salts
by

electrolysis
. Potassium in nature occurs only in ionic salts. As
such, it is found dissolved in

seawater

(which is 0.04% potassium
by weight), and as part of many

minerals
.


Most industrial chemical applications of potassium employ the
relatively high solubility in water of potassium compounds, such as
potassium

soaps
. Potassium metal has only a few special
applications, being replaced in most chemical reactions with
sodium metal.


Potassium ion is necessary for the function of all living cells.
Potassium ion diffusion is a key mechanism in nerve transmission,
and potassium depletion in animals, including humans, results in
various cardiac dysfunctions. Potassium is found in especially high
concentrations within plant cells, and in a mixed diet, it is mostly
concentrated in fruits. The high concentration of potassium in
plants, associated with comparatively low amounts of sodium there,
historically resulted in potassium first being isolated from

potash
,
the ashes of plants, giving the element its name. Heavy crop
production rapidly depletes soils of potassium, and agricultural
fertilizers consume 95% of global potassium chemical production.
[1]