Atoms early Greeks

The contemporary science student is probably aware that the concept of the atom is traceable to early Greek philosophers, notably Democritus. More than likely, however, few have bothered to follow through the hypothetical subdivision process that led to the original concept of an atom. The time has come to remedy this situation since, as mentioned above, the colloidal size range lies between microscopic chunks of material and individual atoms. 

The cathode ray particle is known today as the electron, a name that comes from the Greek word for amber (electrify, which is a material the early Greeks used to study the effects of static electricity. The electron is a fundamental component of all atoms. All electrons are identical, each having a negative electric charge and an incredibly small mass of 9.1 X 10 31 kilogram. Electrons determine many of a material s properties, including chemical reactivity and such physical attributes as taste, texture, appearance, and color. 

Our idea of the atom has come a long way over the last several thousand years. The early Greek idea of the substances was that everything was made up of earth, wind, fire, or water. The idea of an indivisible particle arrived later on, and the word atom was derived from the Greek word atomos, which means indivisible. ... 

The early Greeks, some 2000 years ago, had some ideas that were quite amazing for their time. Look up the philosopher Democritus and his ideas of the atom. 

According to Dalton, elements are composed of only one kind of atom and compounds are made from two or more kinds of atoms. For example, the element copper consists of only one kind of atom, as shown in Figure 4. Notice that the compound iodine monochloride consists of two kinds of atoms joined together. Dalton also reasoned that only whole numbers of atoms could combine to form compounds, such as iodine monochloride. In this way, Dalton revised the early Greek idea of atoms into a scientific theory that could be tested by experiments. 

The origin of atomic theory dates back to the early Greek philosophers. " Boyle in 1661 wrote of those theories of former philosophers, which are now with great applause revived, as discovered by latter ones. ... 

Following the early Greek era, interest in atomic theory waned and was only revived by the writings of Gassendi (1592-1655). For instance, Boyle and Lemery made extensive use of it. Boyle states, It seems not absurd to conceive that at the first Production of mixt Bodies, the Universal matter whereof they among other Parts of the Universe consisted, was actually divided into little particles of several sizes and shapes variously mov d. ... 

The building bricks of elements are called atoms. They are the smallest part of an element that chemically reacts like a bulk sample of the element. If it were possible to take a piece of copper and divide it into smaller and smaller pieces, eventually we would have one atom of copper. Atoms are incredibly small - 35 000 000 copper atoms, laid end to end in a line, would cover a distance of about 1 cm. The existence of atoms has been proposed since the time of the early Greeks and it explains the behaviour of substances. The scanning tunnelling microscope, developed in 1981, enables us to see atoms (see Box 2.2). 

Philosophers from the earliest times speculated about the nature of the fundamental stuff from which the world is made. Democritus (460-370 Bc) and other early Greek philosophers described the material world as made up of tiny indivisible particles they called atomos, meaning indivisible or uncuttable. Later, however, Plato and Aristotle formulated the notion that there can be no ultimately indivisible particles, and the atomic view of matter faded for many centuries during which Aristotelean philosophy dominated Western culture. 

What kinds of evidence did Dalton have for atoms that the early Greeks (Democritus, Leucippus) did not have ... 

In the last 200 years, vast amounts of data have been accumulated to support atomic theory. When atoms were originally suggested by the early Greeks, no physical evidence existed to support their ideas. Early chemists did a variety of experiments, which culminated in Dalton s model of the atom. Because of the limitations of Dalton s model, modifications were proposed first by Thomson and then by Rutherford, which eventually led to our modern concept of the nuclear atom. These early models of the atom work reasonably well—in fact, we continue to use them to visualize a variety of chemical concepts. There remain questions that these models cannot answer, including an explanation of how atomic structure relates to the periodic table. In this chapter, we will present our modern model of the atom we will see how it varies from and improves upon the earlier atomic models. 

Early Greek philosophers also believed that matter was composed of tiny, indivisible particles that they called atoms, from a Greek word that means indivisible. Aristotle, one of antiquity s most influential philosophers in areas of natural science, discounted the existence of atoms and asserted that matter, in principle at least, can be divided over and over again indefinitely. 

Greek lettering is here used with the normal nitroxide convention that the atom bonded to nitrogen is a, etc., i.e. Zr—Y —C0—N(R)0. This differs from occasional early usage in... 

Leopold May goes back even further in time to outline a variety of atomistic ideas from aronnd the world. His chapter Atomism before Dalton concentrates on conceptions of matter that are more philosophical or religiotts than scientific, ranging from ancient Hindu, to classical Greek, to alchemical notions, before touching on a few concepts from the period of early modem science. May is Professor of Chemistry, Emeritus, at the Catholic University of America in Washington, DC. 

ISOTOPE. An isotope is one of nvo or more nuclides ibal have the same number of protons in iheir nuclei. An> two isotopes have ihe same aiuniic number. However. their mass numbers, A. differ. Isotope is a term that stems from the Greek words, isos tsume) and topos (place , to designate substances having different atomic weights and vei having chemical properties so much alike I hat in the early days ol research ii was nor possible to perform ti chemical separation ol the isotope of a given element. 

There was one early hint at the modern way of thinking of elements, from the ancient Greek scholar Democritus (-460--370 b.c.), who thought that materials like fire were made up of tiny invisible particles that could not be broken into smaller pieces. The word he used for these particles is atomos. Atoms, as they are called today, are the particles that make up elements. The element gold is made up of gold atoms the element lead is made of lead atoms, and so on. 

The Curie brothers were drawn to the subject of piezoelectricity because of their familiarity with a phenomenon known for many centuries, that of pyroelectricity. Pyroelectricity refers to the tendency of certain materials to generate an electric current when they are heated. The phenomenon was first described in 314 b.c.e. by the Greek philosopher Theophrastus (ca. 370-ca. 285 b.c.e.), who observed the effect with the mineral tourmaline. Little research was done on pyroelectricity until the early 1800s, when the effect was rediscovered and studied in detail by the Scottish physicist Sir David Brewster (1781-1868). Then in 1878, William Thomson, Lord Kelvin (1824-1907), offered an explanation of the atomic changes that take place when pyroelectric effects occur. These developments in the understanding of pyroelectricity led the Curie brothers to study the possibility of producing electricity from crystals by physical means other than heating. 

Mercury and its compounds have a long and rich history. Its atomic symbol is derived from the Greek name Hydragyrum meaning watery silver. The English word for the element comes from the name of the Roman messenger god because of mercury s liquid mobility and quickness . As early as the second millennium b.c., mercury may have been recovered and nsed in Egypt. Recovery of the element from... 

The first four members of many homologous series often have trival or non-systematic names, many dating back to the early history of chemistry, but from then on they have more systematic names which show how many carbon atoms there are present eg n = 5 is pentane, ( pent meaning five in Greek). Hex means six in Greek, so = 6 = hexane. 

In its elemental form, arsenic is an odorless, tasteless semimetallic compound, which appears steel gray in color, is brittle and is a crystalline solid. The symbol is As the atomic number is 33. Arsenic compounds were mined by the early Chinese, Greek, and Egyptian... 

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