Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes. The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond.

Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs, carbon nanotubes, carbon nanobuds and nanofibers. Several other exotic allotropes have also been discovered, such as lonsdaleite, glassy carbon, carbon nanofoam and linear acetylenic carbon (carbyne).

The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, which is essentially graphite but not held in a crystalline macrostructure. It is present as a powder, and is the main constituent of substances such as charcoal, lampblack (soot) and activated carbon. At normal pressures carbon takes the form of graphite, in which each atom is bonded trigonally to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons.

The resulting network is 2-dimensional, and the resulting flat sheets are stacked and loosely bonded through weak van der Waals forces. This gives graphite its softness and its cleaving properties (the sheets slip easily past one another). Because of the delocalization of one of the outer electrons of each atom to form a π-cloud, graphite conducts electricity, but only in the plane of each covalently bonded sheet. This results in a lower bulk electrical conductivity for carbon than for most metals.

The delocalization also accounts for the energetic stability of graphite over diamond at room temperature. At very high pressures carbon forms the more compact allotrope diamond, having nearly twice the density of graphite. Here, each atom is bonded tetrahedrally to four others, thus making a 3-dimensional network of puckered six-membered rings of atoms.

Diamond has the same cubic structure as silicon and germanium and because of the strength of the carbon-carbon bonds, it is the hardest naturally occurring substance in terms of resistance to scratching. Contrary to the popular belief that "diamonds are forever", they are in fact thermodynamically unstable under normal conditions and transform into graphite.

 However, due to a high activation energy barrier, the transition into graphite is so extremely slow at room temperature as to be unnoticeable. Under some conditions, carbon crystallizes as lonsdaleite. This form has a hexagonal crystal lattice where all atoms are covalently bonded. Therefore, all properties of lonsdaleite are close to those of diamond.

Fullerenes have a graphite-like structure, but instead of purely hexagonal packing, they also contain pentagons (or even heptagons) of carbon atoms, which bend the sheet into spheres, ellipses or cylinders. The properties of fullerenes (split into buckyballs, buckytubes and nanobuds) have not yet been fully analyzed and represent an intense area of research in nanomaterials. The names "fullerene" and "buckyball" are given after Richard Buckminster Fuller, popularizer of geodesic domes, which resemble the structure of fullerenes.

The buckyballs are fairly large molecules formed completely of carbon bonded trigonally, forming spheroids (the best-known and simplest is the soccerball-shaped C60 buckminsterfullerene). Carbon nanotubes are structurally similar to buckyballs, except that each atom is bonded trigonally in a curved sheet that forms a hollow cylinder. Nanobuds were first reported in 2007 and are hybrid bucky tube/buckyball materials (buckyballs are covalently bonded to the outer wall of a nanotube) that combine the properties of both in a single structure.

Of the other discovered allotropes, carbon nanofoam is a ferromagnetic allotrope discovered in 1997. It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web, in which the atoms are bonded trigonally in six- and seven-membered rings. It is among the lightest known solids, with a density of about 2 kg/m3.

Similarly, glassy carbon contains a high proportion of closed porosity, but contrary to normal graphite, the graphitic layers are not stacked like pages in a book, but have a more random arrangement. Linear acetylenic carbon has the chemical structure -(C:::C)n-. Carbon in this modification is linear with sp orbital hybridization, and is a polymer with alternating single and triple bonds.

This type of carbyne is of considerable interest to nanotechnology as its Young's modulus is forty times that of the hardest known material – diamond.(


There exist two different spin isomers of hydrogen diatomic molecules that differ by the relative spin of their nuclei. In the orthohydrogen form, the spins of the two protons are parallel and form a triplet state with a molecular spin quantum number of 1 (½+½); in the parahydrogen form the spins are antiparallel and form a singlet with a molecular spin quantum number of 0 (½–½).

At standard temperature and pressure, hydrogen gas contains about 25% of the para form and 75% of the ortho form, also known as the "normal form". The equilibrium ratio of orthohydrogen to parahydrogen depends on temperature, but because the ortho form is an excited state and has a higher energy than the para form, it is unstable and cannot be purified.

At very low temperatures, the equilibrium state is composed almost exclusively of the para form. The liquid and gas phase thermal properties of pure parahydrogen differ significantly from those of the normal form because of differences in rotational heat capacities, as discussed more fully in spin isomers of hydrogen. The ortho/para distinction also occurs in other hydrogen-containing molecules or functional groups, such as water and methylene, but is of little significance for their thermal properties.

The uncatalyzed interconversion between para and ortho H2 increases with increasing temperature; thus rapidly condensed H2 contains large quantities of the high-energy ortho form that converts to the para form very slowly. The ortho/para ratio in condensed H2 is an important consideration in the preparation and storage of liquid hydrogen: the conversion from ortho to para is exothermic and produces enough heat to evaporate some of the hydrogen liquid, leading to loss of liquefied material.

Catalysts for the ortho-para interconversion, such as ferric oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromic oxide, or some nickel compounds, are used during hydrogen cooling.

Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted H, and is used when hydrogen forms a compound with a more electropositive element. The existence of the hydride anion, suggested by Gilbert N. Lewis in 1916 for group I and II salt-like hydrides, was demonstrated by Moers in 1920 by the electrolysis of molten lithium hydride (LiH), producing a stoichiometry quantity of hydrogen at the anode.

For hydrides other than group I and II metals, the term is quite misleading, considering the low electronegativity of hydrogen. An exception in group II hydrides is BeH
, which is polymeric. In lithium aluminium hydride, the AlH
anion carries hydridic centers firmly attached to the Al(III).
Although hydrides can be formed with almost all main-group elements, the number and combination of possible compounds varies widely; for example, there are over 100 binary borane hydrides known, but only one binary aluminium hydride. Binary indium hydride has not yet been identified, although larger complexes exist.

In inorganic chemistry, hydrides can also serve as bridging ligands that link two metal centers in a coordination complex. This function is particularly common in group 13 elements, especially in boranes (boron hydrides) and aluminium complexes, as well as in clustered carboranes.(


Dinamai sesuai nama perancangnya, Gustave Eiffel , Menara Eiffel adalah bangunan tertinggi di Paris dan salah satu struktur terkenal di dunia. Lebih dari 200.000.000 orang telah mengunjungi menara ini sejak pembangunannya tahun 1889.termasuk 6.719.200 orang tahun 2006.

Menjadikannya monumen berbayar yang paling banyak dikunjungi di dunia. Termasuk antena setinggi 24 m (79 kaki), struktur ini memiliki tinggi 325 m (1.063 kaki) sejak 2000, yang sama dengan bangunan konvensional bertingkat 81.

Ketika menara selesai dibangun tahun 1889, struktur ini menjadi yang tertinggi di dunia — gelar yang dipertahankan hingga 1930 ketika Chrysler Building di New York City (319 m — 1.047 kaki) selesai.

Menara ini sekarang yang tertingggi kelima di Perancis dan paling tinggi di Paris, dengan struktur tertinggi kedua Tour Montparnasse (210 m — 689 kaki), meskipun akan dikalahkan oleh Tour AXA (225.11 m — 738.36 kaki).

Struktur besi Menara Eiffel berbobot 7.300 ton sementara keseluruhan struktur termasuk komponen non-besi berbobot 10.000 ton. Tergantung temperatur, puncak menara dapat menjauhi matahari 18 cm (7 inci) karena pemuaian besi pada bagian yang menghadap matahari. Menara ini juga berayun 6-7 cm (2-3 inci) dalam suasana berangin.

 Sebagai demonstrasi terhadap ekonomisnya bangunan, bila 7300 ton struktur besi dicairkan, maka akan memenuhi 125 meter persegi dengan kedalaman 6 cm (2.36 inci), yang berarti kepadatan besi 7.8 ton per meter kubik.

Menara ini memiliki massa yang kurang dari massa udara di dalam silinder dengan dimensi yang sama, setinggi 324 meter dan 88.3 jari-jarinya. Berat menara 10.100 ton bila dibandingkan dengan 10.265 ton udara.(


Semut adalah semua serangga anggota suku Formicidae, bangsa Hymenoptera. Semut memiliki lebih dari 12.000 jenis (spesies), sebagian besar hidup di kawasan tropika. Sebagian besar semut dikenal sebagai serangga sosial, dengan koloni dan sarang-sarangnya yang teratur beranggotakan ribuan semut per koloni.

Anggota koloni terbagi menjadi semut pekerja, semut pejantan, dan ratu semut. Dimungkinkan pula terdapat kelompok semut penjaga. Satu koloni dapat menguasai daerah yang luas untuk mendukung kehidupan mereka. Koloni semut kadangkala disebut "superorganisme" karena koloni-koloni mereka yang membentuk sebuah kesatuan.

Meskipun ukuran tubuhnya yang relatif kecil, semut termasuk hewan terkuat di dunia. Semut jantan mampu menopang beban dengan berat lima puluh kali dari berat badannya sendiri, dapat dibandingkan dengan gajah yang hanya mampu menopang beban dengan berat dua kali dari berat badannya sendiri. Semut hanya tersaingi oleh kumbang badak yang mampu menopang beban dengan berat 850 kali berat badannya sendiri.

Asam format disebut juga "asam semut" karena semut menghasilkan asam ini sebagai alat pertahanan diri. Keluarga Formicidae adalah bagian dari ordo Hymenoptera, yang mencakup lebah dan tawon. Semut adalah keturunan dari generasi tawon Vespoidea.

Analisis Filogenetik mengindikasikan bahwa semut telah berevolusi dari capung vespoid pada periode Kapur sekitar 120 juta sampai 170 juta tahun yang lalu. Setelah kemunculan tumbuhan Angiosperma sekitar 100 juta tahun yang lalu, mereka menganekaragamkan pengaruh ekolofi sekitar 60 juta tahun yang lalu.

Beberapa dari periode Kapur adalah bentuk pertengahan dari semut dan tawon, dan ini menambahkan bukti bagi nenek moyang tawon. Seperti hewan berordo Hymenoptera lainnya, sistem genetika semut ditemukan di haplodiploidy.

Pada tahun 1966, E. O. Wilson, dkk. menemukan fosil semut dalam getah pohon (Sphecomyrma freyi) dari periode Kapur. Fosil ini terjebak di sebuah getah pohon di New Jersey dan telah berumur lebih dari 80 juta tahun.

Fosil ini memberikan bukti terjelas tentang hubungan semut modern dan tawon non-sosial. Semut periode Kapur berbagi karakteristik semut modern dan tawon. (


Seberapa banyak penduduk yang dimiliki oleh Indonesia sebagai salah satu negara berpenduduk terbesar di dunia? Jumlah seluruh penduduk di Indonesia, pastinya akan kalah jika dibandingkan dengan pengguna aktif Facebook per bulannya. Bahkan jumlah pengguna aktif Facebook mobile pun juga masih lebih banyak.

Hal tersebut terungkap dalam laporan kuartal ketiga 2013 Facebook. Facebook mengungkapkan bahwa saat ini mereka mempunyai sebanyak 1.19 miliar pengguna aktif di seluruh dunia, dan terdapat rata-rata 728 juta pengguna aktif pada bulan September 2013.

Sementara itu pengguna Facebook Mobile aktif per bulan mencapai angka 874 juta. Angka tersebut pun menunjukkan bagaimana perkembangan jumlah pengguna Facebook dari waktu ke waktu.

Terdapat peningkatan sebesar 18 persen pengguna aktif per bulan dibandingkan tahun lalu. Dan untuk pengguna mobile aktif, Facebook memperoleh sukses besar dengan adanya peningkatan sebesar 45 persen dibandingkan tahun 2012.

Saat ini hampir 73.44 pengguna Facebook mengakses akunnya dari perangkat mobile. Tingginya angka pengguna mobile tersebut pun memuaskan para pemegang saham Facebook. Dan pada tahun 2014 mendatang, diperkirakan porsi pengguna Facebook secara mobile mencapai angka sebesar 80 persen. (


Menarik apa yang terjadi di Jerman, disana serikat pekerja yang menaungi profesi jurnalis atau wartawan menyarankan anggotanya Kamis (31/10) tidak dulu menggunakan mesin pencari Google dan Yahoo karena diindikasikan ada operasi intelejen AS dan Inggris.

Inilah bunyi pernyataan dari juru bicara serikat mewakili 38.000 wartawan, Michael Konken, " The German Federation of Journalists menganjurkan wartawan untuk menghindari sampai pemberitahuan lebih lanjut.

Penggunaan mesin pencari dan layanan email dari Google dan Yahoo dalam komunikasi data digital." Semuanya bermula saat muncul skandal kecurangan pencurian lalu lintas data yang dilakukan U.S. National Security Agency (NSA) and Britain's GCHQ.

Sebelumnya santer diberitakan jika NSA menyadap langsung ke link komunikasi Google dan Yahoo untuk memindahkan sejumlah besar email dan informasi pengguna pada pusat data di luar negeri, disebutkan juga program join operasi bersama dengan GCHQ.

Pemerintah Jerman bahkan minggu lalu cukup meradang dan mengatakan memiliki bukti bahwa ponsel Kanselir Angela Merkel telah dipantau oleh intelijen AS, padahal negara ini tergolong memiliki salah satu undang-undang privasi paling ketat di dunia, dilansir oleh Reuters.

Deutsche Telekom juga menyatakan keinginan mereka bersatu ke perusahaan Jerman, United Internet, untuk bekerja sama melindungi lalu lintas internet lokal dari intrusi dan intervensi badan intelijen asing melalui wacana program bertajuk,“ E-mail made in Germany" untuk melindungi lalu-lintas email client, yang dimulai pada bulan Agustus lalu. (