Discovery of The Noble Gasses.

In the late 1800s Johan William Strut, Third Baron of Rayleigh who was a professor of physics at the Cavendish Laboratory in Cambridge, England, accurately determined the atomic masses of a number of elements, but he obtained puzzling results with nitrogen. One of his methods of preparing nitrogen was by thermal decomposition of ammonia.

Another method was to start with air and remove from its oxygen, carbon dioxide, and water vapor. Invariably, the nitrogen from the air was a little denser than the nitrogen from ammonia. Lord Rayleigh’s work caught the attention of Sir William Ramsay, a professor of chemistry at the University College London. In 1898 Ramsay passed nitrogen, which he had obtained by Rayleigh’s procedure over hot magnesium to turn it into magnesium nitride.

After all of the nitrogen had reacted with magnesium, Ramsay was left with unknown gas would couldn’t combine with anything. With the help of Sir William Crookes, Ramsay and Lord Rayleigh found that the emission of spectrum of the gas did not match any of the known elements. They came to conclude that is was a new type of element. They determined its atomic mass to be 39.95amu and called it argon. With this new argon found, other noble gasses were quick to be discovered. Also in 1898 Ramsay isolated helium from uranium ore. From the atomic masses of helium and argon, their lack of chemical reactivity and what was known about the periodic table, Ramsay was convinced that there were other unreactive gasses and that they were all member of one unreactive group. He and his student, Morris Travers set out to find the unknown gasses. They used a refrigeration machine called the fractional distillation; they then allowed the liquid air to warm up gradually and collected components that boiled off at different temperature. Into his manner, they analyzed and identified three new elements-neon, krypton and xenon- in only three months. This new three elements in three months were never broken as a record.

Finally, the last member of the noble gases, radon, was discovered by the German chemist Frederick Dorn in 1900. A radioactive element and the heaviest elemental gas known, radon’s discovery not only completed the Group 8A elements, but also advanced our understanding about the nature of radioactive decay and transmutation of elements.

Lord Rayleigh and Ramsay both won Nobel Prizes in1904 for the discovery of Argon. Lord Rayleigh received the prize in physics and Ramsay’s award was in chemistry.

Plastics

Toys, compact disc, plastic bags, Tupperware do u have any ideas what materials is these items made of? Most people don’t know but they don’t even bother to do. These items sometimes will be immediately disposed without knowing the side effects or the pollution it may cause to the environment. These items are made out of plastics.

These plastics can be made from cellulose from plant oil. And most commonly it is made from petroleum same as what we use to fuel our car. The petroleum we used to fuel our car is formed in all organic matters which are buried deep inside our Earth, after a long period of time it will eventually become crude oil which is also know as petroleum. Not 100% of these petroleum are use to fuel our car, 16% of the petroleum will be process to make plastics. Additives will also be added to form plastics.

The technological route from fuel to plastic products has a numerous way but here will be an example for it. Petroleum was drilled out and transport to refinery. This petroleum will then be refined into ethane propane and also hundreds of petrochemical substances including the fuel for our car. The ethane and propane are then break into ethylene and propylene in a reactor by using high temperature furnaces. After that, a catalyst will be added with ethylene and propylene in a reactor and produce a powder like polymer which resembles laundry detergent. Then this fluff will be combined with additives in a continuous blender. Then this polymer will fed to an extruder where it is melted. Melted plastic is cooled and cut into small pellets by a pelletizer. Then these pellets will then shipped out to customers who order. The customers will eventually manufacture the plastic products by using processes such as extrusion, injection molding, blow molding and etc.

Government, college and also corporation nowadays are trying to change this petroleum-based plastics into biodegradable based. But there is a barrier which stop them from doing so which is the cost. The biobased major materials will be the plant oil but with the rising of the plant oil prices , it will seems hard for them to changed it immediately. Water bottles, food containers, water pipe most of these was made from petroleum based plastics therefore, it will be very hard for them to change it.

When people had used up these things they decide to dispose it. But all these petroleum-based plastics are hard to decay and estimated to have a 500 years lifespan which will become garbage which end up in the landfill for centuries. This is because they are made from non-renewable petrochemicals, styrene and a key ingredient of polymer which is carcinogen which are known as a hazardous substance.

Plastic can release harmful and cancerous chemical that is why nowadays a lot of country had started to banned plastic. For an example, plastic bottle made of polycarbonate can release a chemical called Bisphenol A (BPA), this chemical also known as a kind of environmental estrogen. This chemical can be released when it was exposed to hot boiling water no matter the plastic bottle is new or used. This chemical is harmful is because it can disrupt the endocrine system of a man.

Figure 1 Bisphenol A

Therefore, plastics are really harmful to us and also the environment. We do hope that there will be a better future for out kids so think twice before using a plastics bag because there is always a second choice.

Boron Neutron Capture Therapy

Boron Neutron Capture Therapy. Each year more than half a million of people in the world contract brain tumors and about 2000 die from the disease. Treatment of a brain tumor is one of the most challenging of cancer cases because of the site of the malignant growth, which makes surgical excision difficult and often impossible. Likewise, conventional radiation therapy using X-ray or y- rays from outside the skull is seldom effective.

An ingenious approach to this problem is called boron neutron capture therapy (BNCT). This technique brings together two components, each of which separately has minimal harmful effects on the cells. This first approach uses a compound containing stable boron isotope that can be concentrated in tumor cells. The second component is a beam of low energy neutrons. Upon capturing a neutron, the following nuclear reaction takes place.

The recoiling alpha particle and the lithium nucleus together carry about 3.8x10^-13 J of energy. Because these high energy particles are confined to just a few nana meters; about the cell of a cell, they can perfectly destroy tumor cells without damaging the surrounding tissues. Ionizing radiation like X-rays requires oxygen to produce reactive hydroxyl and superoxide radicals to enhance their biological effectiveness. However, a rapidly expanding tumor frequently depletes its blood supply and hence also the oxygen content. BNCT does not require oxygen and therefore does not suffer from this limitation. BNCT is currently an active research area involving collaboration of chemists, nuclear physicists and physicians.

Scented Smoke; Perfumes.

What is perfume? A nice, attractive and sweet scented solvent which applied to men and women’s body were people first thought about it. Nowadays, many people use perfumes during special occasions and even casual days. Why the sweet smell can last for so long? What are the ingredients that made perfumes have such a nice smell? Are the chemicals used to made perfumes will harm our body? Most of the people might not know what are behind of the perfumes.

Figure 1: Branded Perfumes

The word perfume is derives from a Latin words “per fumus” which means through smoke. In ancient times, people used herbs and spices, like almond, coriander, myrtle, conifer resin, bergamot, as well as flowers to make perfumes. The main purpose of the creation of perfumes during ancient times is for women to attract men. But in modern days now, due to great advances in the technology of perfume creation (i.e. compound design and synthesis) as well as the natural development of styles and tastes; new categories have emerged to describe modern scents. Plants, animals, synthetic sources and other natural sources are the major aromatic ingredients of perfumes. The methods used to extract perfume ingredients from their natural sources have changed over time as technology has advanced. Based on the material, expression, distillation, and solvent extraction are the main techniques used to extract the odorant components from a natural source. Synthetic organic chemistry has provided perfumers with pleasantly new ingredients that are cheaper and more stable than many natural materials over the years.

How long can the scent last on our body?

Most of the perfumes are made up of alcohol. The odourless alcohol used in perfumery is ethanol. In fact, most perfumes are engineered to have a three-part smell or also known as three sets of notes, which spread out after apply it to skin. The word note is just a characteristic language of perfumes for an individual smell. The top notes are the first get to smell it. People will get to smell top notes within the first 15 minutes after applying. Top notes consist of small, light molecules that evaporate quickly. These chemicals first evaporate off your skin. Designers often put weird, unpleasant smells in this phase so that they interest people but the smell doesn’t hang around long enough to feel disgusting. After top notes evaporate, Heart notes appear after 3 to 4 hours. The chemicals used to creating these smells evaporate more slowly than top notes from your skin. In this phase, the original smell of perfume will appear. If it is a floral perfume, flowery smells go here. Base notes stick stubbornly to your skin. You smell them within 5 to 8 hours of application. Musky, watery, mossy and woody chemicals often go in the base.

What is in the scent?

Different brands of perfume have their own recipe of making it. The precise formulas of perfumes are kept secret. The basic ingredients of making a perfume are water, alcohol, fragrance oils and chemical compounds. These four ingredients mix together to form the basic structure of a perfume. However the variations of fragrant oils and other chemical additives used in each perfume are never end. In ancient times, people used herbs, spices, oils and flowers to make perfumes. All the ingredients were extracted from natural sources. Nowadays, many natural extracts have been replaced by synthetic compounds and the once alchemic process is now highly industrialized.

Pollution caused by perfumes

Did you know that perfumes are also harmful? A perfume that smells attractively also can damage our health and environment. According to a research, there are roughly over 500 chemicals just in the ingredient "fragrance" in perfumes. Many of these synthetic chemicals are derived from petrochemicals and are proven neurotoxins which can cause damage to nervous system and carcinogens which can lead to cancer. Some of the most common chemicals in perfumes are ethanol, benzaldehyde, benzyl acetate, acetone, benzyl alcohol, ethyl acetate, methylene chloride and limonene. Some of these chemicals are harmless, but most in this ingredient list can cause irritability, mental vagueness, muscle pain, asthma, joint aches, fatigue, sore throat, eye irritation, gastrointestinal problems, headaches, dizziness, coughing, and itching skin irritations.

Synthetic musk, a class of synthetic aroma chemical in perfumes has pleasant in smell and relatively inexpensive. Hence, synthetic musks are often employed in large quantities to cover the unpleasant scent of perfumes. Due to their large scale use, several types of synthetic musks have been found in human fat and milk, as well as in the sediments and waters of lakes. These pollutants may cause additional health and environmental problems when they enter human and animal diets.

Figure 2: Synthetic Musk Blocked The Transporter

Figure 3: Synthetic Musk

The Effects of Aerosols had on Climate Changes.

Aerosols are tiny particles found in the air. Some occur naturally while some originate from volcanoes, dust storms, forest and grassland fires, living vegetation, and even sea spray. Human activities, such as the burning of fossil fuels and the alteration of natural surface cover, and fossil fuel burning also contributes to most of the emmitions of aerosols. Averaged over the globe, aerosols made by human activities currently account for about 10 percent or more of the total amount of aerosols found in our atmosphere.

Scientists have much to learn about the way aerosols affect regional and global climate but have yet to accurately quantify the relative impacts on climate of natural aerosols and those of human origin. Moreover, theye do not know in what regions of the planet the amount of atmospheric aerosol is increasing, is diminishing, and is remaining roughly constant. Overall, they are even unsure whether aerosols are warming or cooling our planet. In that sense, the effects of Aerosols are pretty much still hidden in its veil waiting for someone to unlock its sercret.

How Aerosols Affect Our Lives?

Aerosols tend to cause cooling of the Earth's surface immediately below them. Because most aerosols reflect sunlight back into space, they have a "direct" cooling effect by reducing the amount of solar radiation that reaches the surface. The magnitude of this cooling effect depends on the size and composition of the aerosol particles, as well as the reflective properties of the underlying surface. It is thought that aerosol cooling may partially offset expected global warming that is attributed to increases in the amount of carbon dioxide from human activity.

Aerosols are also believed to have an "indirect" effect on climate by changing properties of clouds. Indeed, if there were no aerosols in the atmosphere, there would be no clouds. It is very difficult to form clouds without small aerosol particles acting as "seeds" to start the formation of cloud droplets. As aerosol concentration increases within a cloud, the water in the cloud gets spread over many more particles, each of which is correspondingly smaller. Smaller particles fall more slowly in the atmosphere and decrease the amount of rainfall. In this way, changing aerosols in the atmosphere can change the frequency of cloud occurrence, cloud thickness, and rainfall amounts.

If there are more aerosols, scientists expect more cloud drops to form. Since the total amount of condensed water in the cloud is not expected to change much, the average drop must become smaller. This has two consequences -- clouds with smaller drops reflect more sunlight, and such clouds last longer, because it takes more time for small drops to coalesce into drops that are large enough to fall to the ground. Both effects increase the amount of sunlight that is reflected to space without reaching the surface.

the introduction.

hye,

this is our blog for the chemistry assignment. we are from group 18. hope you guys enjoy and gain some knowledge by reading our blog :)

and just like our blog url, we hope to get full marks for this subject. not just from this assignment, but the subject itself. and ofcourse, we want to get full marks for all of our subject.