Atribut Sang Jendral

Ternyata, sepeninggal Jendral Soedirman, beliau masih meninggalkan benda-benda bersejarah yang dewasa ini terpampang di dinding-dinding Museum, penasaran?

TIK dan Trend IT? Sama saja, tuh....

Orang-orang bilang belajar TIK itu gak penting, karena susah! Eitts, siapa bilang? Yuk simak 'saweran' Filza tentang TIK!

Kata Rifi: SMA itu Seru Banget!

Rifi membungkus cerita SMA-nya dengan bungkusan warna-warni, penasaran bagaimana kisah SMA dia? Baca lebih lanjut

Belajar Singkat Bahasa Jepang, yuk!

Nashir ingin membagi-bagi ilmu 'Ke-Jepangannya' dengan caranya sendiri. Hemm, memangnya benar belajar bahasa Jepang itu tidak sulit?

Simak Review Museum Polisi!

Salah satu penyawer, Adipa Rizky, mengadakan kunjungan museum Polri di Blok M. Penasaran bagaimana kisah singkat 60 menit yang dialaminya?

Tampilkan postingan dengan label Abi Rafdi. Tampilkan semua postingan
Tampilkan postingan dengan label Abi Rafdi. Tampilkan semua postingan

Museum Visit


On Saturday May 29, 2011, I visited the Ashmolean Museum in Oxford, UK with my friend. There we saw and observed many of the museum collections. There are some collections in the museum that drew me to explain in this blog. There are Church of Holy Sepulchre in Jerusalem, Arabic Caligraphy, The Japanese Tea Ceremony, English Guitars, and Georgian Dessert Table.
Church of Holy Sepulchre in Jerussalem
The Church of the Holy Sepulchre, also called the Church of the Resurrection by Eastern Christians, is a church within the walled Old City of Jerusalem. It is a few steps away from the Muristan.
The site is venerated as Golgotha (the Hill of Calvary), where Jesus was crucified, and is said also to contain the place where Jesus was buried (the sepulchre). The church has been an important Christian pilgrimage destination since at least the 4th century, as the purported site of the resurrection of Jesus. Today it also serves as the headquarters of the Greek Orthodox Patriarch of Jerusalem, while control of the building is shared between several Christian churches and secular entities in complicated arrangements essentially unchanged for centuries. Today, the church is home to Eastern Orthodoxy, Oriental Orthodoxy and Roman Catholicism. Anglican and Protestant Christians have no permanent presence in the church.[3]
The latest trend among visitors of the spot (standing outside the Church) is to applaud loudly during bells' ringing. This is to recognize the unique beauty of the Church and its unique history. The origin of this practice is in dispute; one source describes a similar act in the Peter Greenaway movie The Belly of an Architect.
“A man may plaster his house, but he should leave a small area unfinished in remembrance of Jerusalem…”
۞  Sotah, chapter 15, paragraph 12. From the Tosefta, legal rabbinic teachings edited in AD 200-300. The quote refers to the sack of Jerusalem by Rome in AD 70.
The site of the Jewish Temple on Mount, built by Solomon, was leveled by the Roman emperor Hadrian in AD 134, after which Jews were exiled from their city.
The emperor Constantine’s mother Helena was said to have discovered at Golgotha in AD 325-327 the cross on which Christ was crucified. Constantine built the Church of the Holy Sepulchre to mark the site and that of Christ’s nearby tomb. The ‘New Jerusalem’ became a major destination for Christian pilgrims.
The Mount (in Arabic Haram al-Sharif) became sacred to Muslims when in AD 691 the Ummayad ruler Abd al-Malik built the Dome of the Rock, the earliest monument of Islam. The Rock was later identified as the site of Muhammad’s ascension to heaven. It was also sacred to Jews as the site where God called upon Abraham to sacrifice his son Isaac.
The History of the Holy Sepulchre in Jerusalem Model in the Ashmolean museum
These models of the Church of the Holy Sepulchre in Jerusalem were probably made in Bethlehem in 1600-1700, using olive wood, ivory, and mother of pearl. The large model comes apart in lettered sections for easy transport and reassembly, and to give the option of revealing the Shrine of the Tomb. Pilgrims to the Holy Land probably brought the models from Jerusalem to Europe. These models of the church of the Holy Sepulchre in Jerusalem were given to the Bodleian Library, Oxford, in 1841 by the Reverend Dr Robert Mason, a major benefactor of the library. The small model was transferred to the Ashmolean Museum in 1887, and the large in 2008. The large model represents the church and shrines built on the presumed sites of Christ’s crucifixion, burial, and resurrection, after renovation by Christian Crusaders. The small model represents the shrine (edicule) built over the tomb within the church. The church was destroyed by fire in 1808, and then was rebuilt.
Arabic Caligraphy
Arabic holds a particular importance for Muslims for whom it is the language of God as revealed to the Prophet Muhammad, and expressed in writing in the Qur’an. The standardization of its script occurred over time, and its alphabet was adopted to write other languages of the Islamic world, like Persian, Ottoman Turkish, and Urdu.
The Arabic script soon became the most distinctive feature of Islamic art. Calligraphy (beautiful writing) has a prominent place in all arts. Verses from the Qur’an or lines of poetry were frequently inscribed on buildings and objects. Calligraphy was also used to name the patron of a work, explain its function, or describe the society in which it was created.
Below is one of the collection of the Calligrapgy that I found in the Ashmolean Museum:
1.      Square tile with holy names. Iran, 1400-1500. Fritware, with decoration in coloured glazes (cuerda seca). It is inscribed with the names of Allah, the Prophet Muhammad, and his son-in-law and successor Ali in square kufic script. Gift of J.P.D. Dunbabin, EA2003.57
2.      Calligraphic panel, possibly from a cenotaph. Iran, 1400-1500. Wood, with carved decoration. Gift of Axia Ltd, EA1991.74
3.      Page from a manuscript of the Qur’an in maghribi script. North Africa or Spain, 1100-1300. Inks and gold on parchment. EA1993.395
4.      End of a calligraphic tile panel written in naskh script. Turkey, about 1575. Fritware, with polychrome underglaze painting. Reitlinger gift, EA1978.1517
The Japanese Tea Ceremony
‘The tea ceremony requires years of training and practice. Yet the whole of this art, as to its detail, signifies no more than the making and serving of a cup of tea. The supremely important manner is that the ac be performed in the most perfect, most polite, most graceful, most charming manner possible.’
۞  Lafcadio Hearn, Japan: An Attempt at interpretation (1905)
The preparation and drinking of tea in a formal ceremony has been practiced in Japan since the 1400s. this is called chanoyu (‘hot water for tea’). In Japanese tea ceremony participants withdraw from the stresses of daily life to the peaceful setting of a special tea room made of simple natural materials.
The tas master prepares and serves the tea using set movements: scooping powdered green tea into a tea bowl, lading over hot water, mixing the tea with a bamboo whisk and then serving tea to each guest in turn. Conversation is kept to a minimum troughout. After drinking, guests admire the tea utensils carefully selected by the tea master. Even the guests need to use set gestures and phrases.
Ningendo, a Japanese Tea House
The Ashmolean ta house was designed for this space by the Japanese architect Isai Komoda. The tea house was built near Tokyo by the company Amakasu Komuten, which specializes in traditional Japanese architecture. A team of skilled Japanese craftsmen constructed the tea house in Japan, then took it apart, shipped it to England and rebuilt it inside the gallery.
The tea house was named Ningendo by the gallery sponsor, Mr Hiroaki Shikanai. The phrase ‘Ningen’ refers to the qualities of virtue and benevolence, and is associated with the 9th century Buddhist pries Kukai. The name, which is read from right to left, is written in ancient Chinese-style seal script.
English guitars
The English guitar, as it is known is not a guitar at all but a wire strung instrument rather like the cittern. It was very popular in England from about 1750, competing in fashionable society with the harpsichord as an instrument for amateurs. There were several makers specializing in making these instruments at this time.
By the early 1800s, the fashion for the English guitar had ended following the arrival of the Spanish guitar from the continent. The Spanish guitar is still the preferred instrument for many amateur musicians.
Below is one of the English guitar model:
1.      English guitar, by John N. Preston (working 1734-1770) stamped on the peg box: PRESTON MAKER/LONDON. John Preston was one of the leading makers of English guitars in London in the mid-1700’s. this is a typical example of his work. It has six courses of strings (four double) and a device called a capotasto, a bar which is tightened by a nut against the neck for stopping the strings in four positions. This can be used to raise or lower the pitch by a semi-tone. Presented by A. Phillips Hill in accordance with the wishes of Arthur and Alfred Hill. 1948, WA1948.129
Georgian dessert table
This room setting shows a table set for dessert in a prosperous middle class household in England about 1760-1770. It is laid with Worchester dessert plates and dishes of that date, wine and syllabub glasses, and silver from the 1730s. the portrait by Gainsborough dates from about 1750.
Dessert was the final course of dinner. A well-to-do household would use a different porcelain service from that used for the main courses. The table was cleared of salts and pepper pots and other items used for savoury food. The servants would bring in an array of new dishes, which would include fresh, stewed and preserved fruit, sweetmeats, fondants, nuts, biscuits, jellies, and syllabubs in glasses. Syllabub is a mixture of wine, whipped cream and orange or lemon juice. Sweet wine would be served.

References:
۞  Wikipedia.
۞  Ashmolean Museum, Oxford, England.


Mudahnya Belajar Kimia!!

STRUKTUR ATOM

Bentuk Atom
Beberapa pendapat mengenai bentuk/model atom dikemukakan oleh:
1.      John Dalton ( Th 1805)
Yang menyatakan bahwa materi terdiri dari partikel yang disebut atom. Atom tidak dapat dipecah, dimusnahkan atau diciptakan dan tidak dapat diubah menjadi atom lain.
2.      J.J. Thomson (Th 1900)
Mengemukakan bahwa atom bukanlah sesuatu yang tidak terbagi. Atom terdiri dari materi bermuatan positif dan elektron-elektron yang tersebar didalamnya. Elektron dapat berpindah sedangkan proton tidak dapat berpindah. Atom disebut netral jika jumlah proton dan elektronnya sama.
3.      E. Rutherford  (Th 1910)
Mengemukakan bahwa atom terdiri dari inti yang bermuatan positif dan elektron-elektron yang beredar mengitarinya.
4.      Niels Bohr  ( Th 1913)
Penyempurnaan dari model atom E. Rutherford . Menurut Bohr elektron-elektron mengitari inti pada lintasan tertentu yang menyerupai sistem tata surya.
5.      Erwin Schrodinger (Th 1926)
Dikenal dengan model atom mekanika kuantum yang menggambarkan lintasan elektron bagaikan awan disekitar atom.

Penyusun Atom:

1. Elektron
Besarnya muatan dalam elektron ditemukan oleh Robert Andrew Milikan (1908)
melalui percobaan tetes minyak Milikan
Minyak disemprotkan ke dalam tabung yang bermuatan listrik. Akibat gaya
tarik gravitasi akan mengendapkan tetesan minyak yang turun. Bila tetesan
minyak diberi muatan negatif maka akan tertarik kekutub positif medan listrik.
Hasil percobaan Milikan dan Thomson diperoleh muatan elektron –1 dan massa
elektron 0.

2. Proton
Jika massa elektron 0 berarti suatu partikel tidak mempunyai massa padahal
partikel materi mempunyai massa yang dapat diukur. Begitu pula kenyataan
bahwa atom itu netral.
Bagaimana mungkin atom itu bersifat netral dan mempunyai, jika hanya ada
elektron saja dalam atom?
Eugene Goldstein (1886) melakukan eksperimen dari tabung gas yang memiliki
katoda, yang diberi lubang-lubang dan diberi muatan listrik.
Ternyata pada saat terbentuk elektron yang menuju anoda terbentuk pula sinar
positif yang menuju arah berlawanan melewati lubang pada katoda.
Setelah berbagai gas dicoba dalam tabung ini, ternyata gas hidrogenlah yang
menghasilkan sinar muatan positif yang paling kecil baik massa maupun
muatannya, sehingga partikel ini disebut dengan proton.
Massa proton = 1 sma (satuan massa atom) dan muatan proton = +1.

3. Inti atom
Setelah penemuan proton dan elektron, Ernest Rutherford melakukan penelitian
penembakan lempeng tipis. Jika atom terdiri dari partikel yang bermuatan
positif dan negatif maka sinar alpha yang ditembakkan seharusnya tidak ada
yang diteruskan/menembus lempeng sehingga muncullah istilah inti atom.
Ernest Rutherford dibantu oleh Hans Geiger dan Ernest Marsden (1911)
menemukan konsep inti atom didukung oleh penemuan sinar X oleh WC.
Rontgen (1895) dan penemuan zat Radioaktif (1896).

Hasil percobaan ini membuat Rutherford menyatakan hipotesanya bahwa atom
tersusun dari inti atom yang bermuatan positif dan dikelilingi elektron yang
bermuatan negatif. Untuk mengimbanginya sehinga atom bersifat netral.
19
Massa inti atom tidak seimbang dengan massa proton yang ada dalam inti
atom, sehingga dapat dipredisi bahwa ada partikel lain dalam inti atom.

4. Neutron
Prediksi dari Rutherford memacu W. Bothe dan H. Becker (1930) melakukan
eksperimen penembakan partikel alpha pada inti atom berilium (Be). Ternyata
dihasilkan radiasi partikel berdaya tembus tinggi.
Eksperimen ini dilanjutkan oleh James Chadwick (1932). Ternyata partikel
yang menimbulkan radiasi berdaya tembus tinggi itu bersifat netral atau tidak
bermuatan dan massanya hampir sama dengan proton. Partikel ini disebut
neutron dan dilambangkan dengan 1n0 .

B. Nomor Atom dan Nomor Massa
Suatu atom memiliki sifat dan massa yang khas satu sama lain. Dengan penemuan
partikel penyusun aton dikenal istilah nomor atom (Z) dan nomor massa (A).

1. Nomor Atom (Z)
Jumlah proton dalam suatu atom disebut nomor atom yang diberikan lambang
Z. Nomor atom ini merupakan ciri khas suatu unsur, karena atom bersifat
netral maka jumlah proton sama dengan jumlah elektronnya. Sehingga nomor
atom juga menunjukan jumlah elektron.
Elektron inilah yang nantinya paling menentukan sifat suatu unsur. Nomor
atom ditulis agak ke bawah sebelum lambang unsur. Atom oksigen mempunyai
8 proton dan 8 elektron sehingga nomor atomnya 8.

2. Nomor Massa (A)
Seperti diuraikan sebelumnya massa elektron sangat kecil, dianggap nol.
Sehingga massa atom ditentukan oleh inti atom yaitu proton dan neutron.
Nomor massa ditulis agak ke atas sebelum lambang unsur. Atom oksigen
mempunyai nomor atom 8 dan nomor massa 16, sehingga atom oksigen
mengandung 8 proton dan 8 neutron.
Nomor Massa (A) = Jumlah proton + Jumlah neutron
Atau
Jumlah neutron = Nomor massa – Nomor atom
Penulisan lambang atom unsur menyertakan nomor atom dan nomor massa.
 


dimana:
A = nomor massa
Z = nomor atom
X = lambang unsur
C. Isotop, Isoton dan Isobar
Setelah penulisan lambang atom unsur dan penemuan partikel penyusun atom,
ternyata ditemukan adanya unsur-unsur yang memiliki jumlah proton yang sama
tetapi memiliki massa atom yang sama dan ada pula unsur-unsur yang memiliki
jumlah neutron sama atau massa atom yang sama tetapi nomor atom berbeda.
Untuk itu dikenalkanlah istilah isotop, isoton dan isobar.

1. Isotop
Atom yang mempunyai nomor atom yang sama tetapi memiliki nomor massa
yang berbeda disebut dengan isotop.
Contoh:

14N7
15N7
p = 7 p = 7 p = 7
e = 7 e = 7 e = 7
n = 6 n = 7 n = 8
Setiap isotop satu unsur memiliki sifat kimia yang sama karena jumlah
elektronnya sama.
Isotop-isotop unsur ini dapat digunakan untuk menentukan massa atom relatif
(Ar), atom tersebut berdasarkan kelimpahan istop dan massa atom semua
isotop.
2. Isoton
Seperti yang sudah kita pelajari sebelumnya, bahwa neutron adalah selih antara
nomor massa dengan nomor atom; maka isoton tidak dapat terjadi untuk unsur
yang sama.

3. Isobar
Isobar adalah unsur-unsur yang memiliki nomor massa yang sama. Adanya
isotop yang membuat adanya isobar.
Isotop 12C6

13C6  13C6 dan Isotop 13N7 14N7 15N7
Sehingga antara 13C6 dan 13N7 merupakan isoton.


IKATAN KIMIA

Ikatan Ion
v  ikatan Ion adalah ikatan yang terbentuk akibat gaya tarik – menarik antara ion positif (kation) dengan ion negatif (anion)
v  Ikatan ion terjadi antara atom logam (golongan IA, kecuali H dan Golongan IIA) dengan unsur non logam (golongan VIA dan golongan VIIA)
v   Akan terjadi serah terima elektron sehingga akan terjadinya tarik menarik antara atom logam yang bermuatan positif dengan atom non logam yang bermuatan negatif

Ikatan kovalen
v  Ikatan kovalen adalah ikatan yang terjadi akibat pemakaian pasangan elektron oleh dua arom yang berikatan
v  Ikatan kovalen terbentuk diantara dua atom yang sama-sama ingin menangkap elektron
v  Atom-atom yang biasanya berikatan secara kovalen umumnya yaitu ikatan non logam
v  Gabungan atom-atom melalui ikatan kovalen dinamakan Molekul. Molekul ini berupa molekul unsur (contohnya Cl2, O2, P4) dan Molekul senyawa (contohnya HCl, CO2, CH4)

Jenis Ikatan Kovalen
·         Kovalen koordinasi
o   Ikatan koordinasi adalah ikatan kovalen dimana elektron-elektron dalam pasangan elektron yang digunakan bersama berasal dari salah satu atom yang berikatan
o   Ikatan kovalen ini hanya dapat terbentuk apabila salah satu atum mempunyai pasangan elektron bebas (PEB)
Kepolaran Ikatan
·         Ikatan Kovalen Polar
o   Ikatan kovalen polar tejadi jika pasangan elektron yang dipakai bersama, tertarik lebih kuat ke salah satu atom berikatan
o   Kepolaran senyawa akan bertambah jika beda keelektronegatifan atom-atom yang berikatan semakin besar
·         Ikatan Kovalen non-Polar
o   Ikatan kovalen nonpolar tejadi jika pasangan elektron yang dipakai bersama, tertarik ke semua atom berikatan

Ikatan Logam
·         Ikatan logam adalah ikatan kimia yang terbentuk akibat penggunaan bersama elektron-elektron valensi antara atom-atom logam.