LIST OF ATOMIC RADIUS AND ATOMIC WEIGHTS OF ELEMENTS BASIC INFORMATION

Here is a list of atomic numbers and atomic weights.

The radius of an atom can be estimated by taking half the distance between the nucleus of two of the same atoms. For example, the distance between the nuclei of is 2.66 Å, half that distance would be the radius of atomic iodine or 1.33 Å. Using this method the atomic radius of nearly all the elements can be estimated.

Note that going across the periodic table, the atomic radius decreases. This is due to the fact that the principal energy level (principal quantum number) remains the same, but the number of electrons increase.

The increase in the number of electrons causes an increase in the electrostatic attraction which causes the radius to decrease. However, going down the periodic table the principal energy level increases and hence the atomic radius increases.

Below is a lists the atomic radii of some of the elements.

Below is a list of its atomic weights:

GLENN SEABORG AND SEABORGIUM BASIC INFORMATION AND TUTORIALS

Prior to 1940 the periodic table ended at uranium, element number 92. Since that time, no scientist has had a greater effect on the periodic table than Glenn Seaborg.

In 1940 Seaborg, Edwin McMillan, and coworkers at the University of California, Berkeley, succeeded in isolating plutonium (Pu) as a product of the reaction between uranium and neutrons.

Between 1944 and 1958, Seaborg and his coworkers also identified various products of nuclear reactions as being the elements having atomic numbers 95 through 102. All these elements are radioactive and are not found in nature; they can be synthesized only via nuclear reactions.

For their efforts in identifying the elements beyond uranium (the transuranium elements), McMillan and Seaborg shared the 1951 Nobel Prize in Chemistry.

From 1961 to 1971, Seaborg served as the chairman of the US Atomic Energy Commission (now the Department of Energy). In this position he had an important role in establishing international treaties to limit the testing of nuclear weapons.

Upon his return to Berkeley, he was part of the team that in 1974 first identified element number 106. In 1994, to honor Seaborg’s many contributions to the discovery of new elements, the American Chemical Society proposed that element number 106 be named seaborgium (Sg).

After several years of controversy about whether an element should be named after a living person, the IUPAC officially adopted the name in 1997. Seaborg became the first person to have an element named after him while he was alive.

ATOMIC THEORY OF MATTER - BASIC INFORMATION AND TUTORIALS

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.

The notion of atoms reemerged in Europe during the seventeenth century. As chemists learned to measure the amounts of elements that reacted with one another to form new substances, the ground was laid for an atomic theory that linked the idea of elements with the idea of atoms.

That theory came from the work of John Dalton during the period from 1803 to 1807. Dalton’s atomic theory was based on the four postulates:

1. Each element is composed of extremely small particles called atoms.

2. All atoms of a given element are identical, but the atoms of one element are different from the atoms of all other elements.

3. Atoms of one element cannot be changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions.

4. Compounds are formed when atoms of more than one element combine; a given compound always has the same relative number and kind of atoms.

Dalton’s theory explains several laws of chemical combination that were known during his time, including the law of constant composition, based on postulate 4:

In a given compound, the relative numbers and kinds of atoms are constant. It also explains the law of conservation of mass, based on postulate 3:

The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.

A good theory explains known facts and predicts new ones. Dalton used his theory to deduce the law of multiple proportions:

If two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers.

We can illustrate this law by considering water and hydrogen peroxide, both of which consist of the elements hydrogen and oxygen. In forming water, 8.0 g of oxygen combine with 1.0 g of hydrogen. In forming hydrogen peroxide, 16.0 g of oxygen combine with 1.0 g of hydrogen.

Thus, the ratio of the mass of oxygen per gram of hydrogen in the two compounds is 2:1. Using Dalton’s atomic theory, we conclude that hydrogen peroxide contains twice as many atoms of oxygen per hydrogen atom as does water.

John Dalton (1766–1844), the son of a poor English weaver, began teaching at age 12. He spent most of his years in Manchester, where he taught both grammar school and college. His lifelong interest in meteorology led him to study gases, then chemistry, and eventually atomic theory. Despite his humble beginnings, Dalton gained a strong scientific reputation during his lifetime.

JOB OR WORKS OF CHEMIST - WHAT ARE THE POSSIBLE JOBS FOR CHEMIST?

So What Does a Chemist Do All Day?

You can group the activities of chemists into these major categories:
~ Chemists analyze substances. They determine what is in a substance, how much of something is in a substance, or both. They analyze solids, liquids, and gases. They may try to find the active compound in a substance found in nature, or they may analyze water to see how much lead is present.

~ Chemists create, or synthesize, new substances. They may try to make the synthetic version of a substance found in nature, or they may create an entirely new and unique compound. They may try to find a way to synthesize insulin. They may create a new plastic, pill, or paint. Or they may try to find a new, more efficient process to use for the production of an established product.

~ Chemists create models and test the predictive power of theories. This area of chemistry is referred to as theoretical chemistry. Chemists who work in this branch of chemistry use computers to model chemical systems. Theirs is the world of mathematics and computers. Some of these chemists don't even own a lab coat.

~ Chemists measure the physical properties of substances. They may take new compounds and measure the melting points and boiling points. They may measure the strength of a new polymer strand or determine the octane rating of a new gasoline.

And Where Do Chemists Actually Work?

You may be thinking that all chemists can be found deep in a musty lab, working for some large chemical company, but chemists hold a variety of jobs in a variety of places:

~ Quality control chemist: These chemists analyze raw materials, intermediate products, and final products for purity to make sure that they . fall within specifications. They may also offer technical support for the customer or analyze returned products. Many of these chemists often solve problems when they occur within the manufacturing process.

~Industrial research chemist: Chemists in this profession perform a large number of physical and chemical tests on materials. They may develop new products, and they may work on improving existing products. They may work with particular customers to formulate products that meet specific needs. They may also supply technical support to customers.

~Sales representative: Chemists may work as sales representatives for companies that sell chemicals or pharmaceuticals. They may call on their customers and let them know of new products being developed. They may also help their customers solve problems.

~Forensic chemist: These chemists may analyze samples taken from crime scenes or analyze samples for the presence of drugs. They may also be called to testify in court as expert witnesses.

~Environmental chemist: These chemists may work for water purification plants, the Environmental Protection Agency, the Department of Energy, or similar agencies. This type of work appeals to people who like chemistry but also like to get out in nature. They often go out to sites to collect their own samples.

~Preservationist of art and historical works: Chemists may work to restore paintings or statues, or they may work to detect forgeries. With air and water pollution destroying works of art daily, these chemists work to preserve our heritage.

~Chemical educator: Chemists working as educators may teach physical science and chemistry in public schools. They may also teach at the college or university level. University chemistry teachers often conduct research and work with graduate students. Chemists may even become chemical education specialists for organizations such as the American Chemical Society.

These are just a few of the professions chemists may find themselves in. I didn't even get into law, medicine, technical writing, governmental relations, and consulting. Chemists are involved in almost every aspect of society. Some chemists even write books.

If you aren't interested in becoming a chemist, why should you be interested in chemistry? (The quick answer is probably "to pass a course.,,) Chemistry is an integral part of our everyday world, and knowing something about chemistry will help you interact more effectively with our chemical environment.

LPG CYLINDERS ROAD TRANSPORT SAFETY PROCEDURES BASICS AND TUTORIALS

Procedures for safe transport of LPG cylinders by road.

Transport
• Carry cylinders on open vehicles. Keep cylinders upright and adequately secured, e.g. with a rope.
• Keep a fire extinguisher, e.g. 1 kg dry power, in the cab to deal with any small fire, e.g. an engine fire.
• Do not leave cylinders on vehicles unsupervised.
• Ensure that the driver has received adequate training and instructions about the hazards of LPG, emergency procedures, driver duties, etc.
• Ensure that relevant information is readily available on the vehicle, e.g. on a clipboard in the cab. This written information, e.g. as a TREMCARD, should contain details of the nature of the load and the action to take in an emergency.

Duties of vehicle operator
• Check whether the Road Traffic (Carriage of Dangerous Packages, etc.) Regulations 1986 apply. Exceptions apply to cylinders <5 litres; cylinders which are part of equipment carried on the vehicles, e.g. burning gear, bitumen boilers; cylinders associated with vehicle operation, e.g. cooking, water heating.
• Ensure the vehicle is suitable, normally an open vehicle. Use of a closed vehicle should be restricted to a small number of cylinders with a load compartment having adequate ventilation.
• Ensure the driver has adequate information in writing, e.g. a TREMCARD.
• Ensure the driver is provided with adequate instruction and training and keeps necessary records.
• Ensure loading, stowage, unloading are performed safely. All cylinders should be packed, strapped, supported in frames, or loaded to avoid damage resulting from relative movement. Cylinders should be stowed with valves uppermost.
• Ensure all precautions are taken to prevent fire or explosion.
• Ensure suitable fire extinguishers are provided.
• Ensure the vehicle displays two orange plates if 500 kg of LPG is carried.
• Report any fire, uncontrolled release or escape of the LPG, to the appropriate authority.

Duties of the driver
• Ensure the relevant written information from the operator is always available during carriage. Destroy, remove or lockaway information about previous loads.
• Ensure loading, stowage and unloading are performed safely.
• Ensure all precautions against fire or explosion are taken during carriage.
• Display orange plates (when required) and keep them clean and free from obstruction.
• If >3 tonnes of LPG is carried, when the vehicle is not being driven, ensure parking is in a safe place or that it is supervised (by the driver or a competent person aged >18).
• On request provide appropriate information to persons authorized to inspect the vehicle and load.
• Report any fire, uncontrolled release or escape of LPG, to the operator.

EMERGENCY PROCEDURES FOR DRIVERS IN TRANSPORTING RADIOACTIVE SUBSTANCE

Arrange for the police and emergency services to be alerted

Arrange for assistance to be given to any person injured or in immediate danger

If considered safe to do so – having regard to the nature of the emergency, the substance and the emergency equipment available – follow a selection of the following procedures in an appropriate order:

Stop the engine

Turn off any battery isolating switch

If there is no danger of ignition, operate the emergency flashing device

Move the vehicle to a location where any leakage would cause less harm

Wear appropriate protective clothing

Keep onlookers away

Place a red triangle warning device at the rear of the vehicle and near any spillage

Prevent smoking and direct other vehicles away from any fire risk area

Upon the police/fire brigade taking charge:

Show the written information, e.g. Tremcard, to them

Tell them of action taken and anything helpful about the load, etc.

At the end of the emergency, inform the operator.

The written information given to the driver should include:

The name of the substance

Its inherent dangers and appropriate safety measures

Action and treatment following contact/exposure

Action in the event of fire and fire-fighting equipment to be used

Action following spillage on the road

How and when to use any special safety equipment

HOW WAS THE EARTH FORMED? - BASIC INFORMATION ON THE FORMATION OF PLANET EARTH

The solar system formed about 4.6 billion years ago. The Earth and other terrestrial planets are believed to have formed by gathering together the so-called planetesimals.

Planetesimals are formed by the coalescence of fine- or coarse-grained mineral matters, metals, and gases of various kinds. As planetesimals stuck together mostly by gravity and the body thus formed grew larger, it became a precursor of terrestrial planet.

Some of these bodies were smashed by other bodies, and their fragments became meteorites. Hence, studies of meteorites would provide a lot of insight into the formation and the earlier state of the Earth.

The planet Earth was thus formed. Heat was created as the coalescence (of planetesimals) proceeded due to gravity, and heat also came from radioactivity of several radioactive elements such as aluminum-26. So the newly formed body was heated and the core was melted.

As the material becomes liquid (as a result of melting), the materials contained in the liquid separate out according to their densities. The more dense material would sink closer to the bottom (core).

Thus, the present layer structure of the Earth formed. The innermost core is a dense solid of about 1,200 km radius, whose density is about 12.6 g per cubic centimeter (12.6 ×106 kg/m3).

It is made of mostly iron metal and a small amount of nickel. By the way, the density of iron metal is only 7.8×106 kg/m3 under the ordinary pressure. The next layer is the outer core (up to 3,500 km from the center of the Earth), which is liquid and has a density of 9.5–12×106 kg/m3. The chemical composition seems to be about the same as that of the inner core.

There is an abrupt change in density in the next layer, mantle. The width of mantle is about 2,900 km (3,500–6,380 km from the center). Its density ranges from 4 to 5.5 ×106 kg/m3. The mantle is made of mostly magnesium–iron silicates (silicon oxides). The outermost layer is the thin crust of about 35–45 km on the land portion, and about 6 km under the ocean portion.

IRON (FE) CHEMICAL INFORMATION - THE CHEMISTRY OF IRON

What Is Iron? All you need to know about the element Iron (Fe)

Iron, a familiar metal, tends to rust, as everybody has seen. What happens chemically when iron rusts? Iron atoms in the metallic iron carries no electric charge Fe(0), in which 26 electrons (negatively charged) are orbiting around a nucleus that contains 26 protons (with positive charge) and 30 neutrons (with no electric charge).

This applies to an isotope 26Fe56, the most abundant isotope of element iron. But iron atom can lose its electrons. This process (loss of electrons) is called “oxidation.” Iron becomes either Fe(II) by losing two electrons or Fe(III) by losing three electrons (under normal conditions), though it can take Fe(I) (under special conditions).

Fe(0) is said to have been oxidized to Fe(II) or Fe(III). [Fe(II) means an iron atom that carries two positive charges; this is so because there are now only 24 electrons (negative charges), but there are still 26 positive charges at the nucleus.]

For this to happen you have to have a chemical entity that removes the electrons from the iron atom. Such an entity is called an oxidant or oxidizing agent. The iron atom is said to be a reductant or reducing agent in this process, for a chemical reaction in which a chemical entity (oxidant) gains electron(s) is called “reduction.”

Hence, oxidation and reduction reactions occur simultaneously and are like “head and tail” of a coin. Iron (Fe) reacts with oxygen in the air and is oxidized first to Fe(II) and then Fe(III) ending up with iron oxide Fe2O3. [Fe(II) can also be expressed as Fe2+ or FeII, and such a state is called an “oxidation state”; in this case, the oxidation state of iron atom is +2 or II. Likewise, Fe(III)=FeIII=Fe3+.

We will usually use Roman numerals to express the oxidation states in this book]. Here oxygen (O2) in the air is the oxidizing agent. In the process, oxygen O2 which is in “zero” oxidation state gains four electron and is reduced to two of O−II (−2 oxidation state); therefore, the chemical reaction is + → III ( −II ) 2 2 3 4Fe(0) 3O 2Fe O . In this chemical reaction, 12 electrons are exchanged between four iron atoms and three oxygen molecules.

When this is not purely oxide and contains hydroxide Fe(OH)O or Fe2(OH)2O2, it shows that rust color, brown. Pure oxide Fe2O3 forms an ore called “hematite,” which is red. The red bed is found in many geological locations.

These descriptions suggest that iron, when forming chemical compounds, takes the form of Fe(II) or Fe(III). And it can go back and forth between Fe(II) and Fe(III) readily. Fe(II) gives off an electron to become Fe(III), and Fe(III) becomes Fe(II) when it accepts an electron. This kind of process is also called “electron transfer” reaction.

Hence, iron (in the form of Fe(II) and Fe(III)) can readily undergo an “electron transfer” reaction or alternatively an “oxidation–reduction” reaction, because the process of Fe(II)s becoming Fe(III) is an oxidation and the reverse (Fe(III) → Fe(II)) is a reduction reaction.

Some of you might have experienced, as this author has, to have your toilet bowl and others stained brown by your well water. The water underground can contain (depending on the location and other conditions) iron compounds; the iron is in the form of Fe(II), which is dissolved in water and almost colorless. It remains as Fe(II) in the underground, because no oxidant such as oxygen in the air is available.

However, once pumped out above ground and being exposed to the air, the iron soon turns into Fe(III) (through oxidation by oxygen). Fe(III) in water (neutral water, that is) is not stable, and soon reacts with water itself and forms iron hydroxide Fe(OH)3, which is brown and precipitates.

This is the brown stain. And the fact of the easy formation of iron stain suggests an easy affinity or reaction of Fe(II) with oxygen O2. This is indeed the basis of the usefulness of iron in the biological systems and our health.