boys vs girls
boys have fun by teasing girls,
then girls cry for few minutes
girls have fun by loving boys
then boys cry 4 life time!
funny but it is fact :-)beryllium, 4be
general properties
name, symbol beryllium, be
appearance white-gray metallic
pronunciation /b��r�li�m/
b�-ril-ee-�m
beryllium in the periodic table
–
↑
be
↓
mg
lithium ← beryllium → boron
atomic number (z) 4
group, block group 2 (alkaline earth metals), s-block
period period 2
element category alkaline earth metal
standard atomic weight (�) (ar) 9.0121831(5)[1]
electron configuration [he] 2s2
per shell
2, 2
physical properties
phase solid
melting point 1560 k (1287 �c, 2349 �f)
boiling point 2742 k (2469 �c, 4476 �f)
density near r.t. 1.85 g/cm3
when liquid, at m.p. 1.690 g/cm3
critical point 5205 k, mpa (extrapolated)
heat of fusion 12.2 kj/mol
heat of vaporization 292 kj/mol
molar heat capacity 16.443 j/(mol�k)
vapor pressure
p (pa) 1 10 100 1 k 10 k 100 k
at t (k) 1462 1608 1791 2023 2327 2742
atomic properties
oxidation states +2, +1[2] (an amphoteric oxide)
electronegativity pauling scale: 1.57
ionization energies 1st: 899.5 kj/mol
2nd: 1757.1 kj/mol
3rd: 14,848.7 kj/mol
(more)
atomic radius empirical: 112 pm
covalent radius 96�3 pm
van der waals radius 153 pm
miscellanea
crystal structure hexagonal close-packed (hcp)
speed of sound thin rod 12,890 m/s (at r.t.)[3]
thermal expansion 11.3 �m/(m�k) (at 25 �c)
thermal conductivity 200 w/(m�k)
electrical resistivity 36 n��m (at 20 �c)
magnetic ordering diamagnetic
young's modulus 287 gpa
shear modulus 132 gpa
bulk modulus 130 gpa
poisson ratio 0.032
mohs hardness 5.5
vickers hardness 1670 mpa
brinell hardness 590–1320 mpa
cas number 7440-41-7
history
discovery louis nicolas vauquelin (1797)
first isolation friedrich w�hler & antoine bussy (1828)
most stable isotopes of beryllium
iso na half-life dm de (mev) dp
7be trace 53.12 d � 0.862 7li
� 0.477 –
9be 100\% 9be is stable with 5 neutrons
10be trace 1.36�106 y �− 0.556 10b
beryllium is a chemical element with symbol be and atomic number 4. it is created through stellar nucleosynthesis and is a relatively rare element in the universe. it is a divalent element which occurs naturally only in combination with other elements in minerals. notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl. as a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal.
beryllium improves many physical properties when added as an alloying element to aluminium, copper (notably the alloy beryllium copper), iron and nickel.[4] tools made of beryllium copper alloys are strong and hard and do not create sparks when they strike a steel surface. in structural applications, the combination of high flexural rigidity, thermal stability, thermal conductivity and low density (1.85 times that of water) make beryllium metal a desirable aerospace material for aircraft components, missiles, spacecraft, and satellites.[4] because of its low density and atomic mass, beryllium is relatively transparent to x-rays and other forms of ionizing radiation; therefore, it is the most common window material for x-ray equipment and components of particle physics experiments.[4] the high thermal conductivities of beryllium and beryllium oxide have led to their use in thermal management applications.
the commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease in some people called berylliosis.[5]
contents
[hide]
1 characteristics
1.1 physical properties
1.2 nuclear properties
1.3 isotopes and nucleosynthesis
1.4 occurrence
2 production
3 chemical properties
4 history
4.1 etymology
5 applications
5.1 radiation windows
5.2 mechanical applications
5.3 mirrors
5.4 magnetic applications
5.5 nuclear applications
5.6 acoustics
5.7 electronic
6 precautions
7 see also
8 notes
9 references
1
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