CIR Room 9: July 2010

Tuesday, July 6, 2010

Antoine Lavoisier

Biography of Antoine Lavoisier
- Born on August 26, 1743 in Paris, France, Antoine Lavoisier was born to a wealthy family in Paris, he inherited a large fortune at the age of five with the passing of his mother. He attended the College Mazarin in 1754 until 1761. He studied chemistry, botany, astronomy and mathematics. His first ever chemical publication appeared in 1764. At the age of 25, he was elected a member of the French Academy of Sciences, France`s most elite scientific society, for an essay on street lighting, and in recognition for his earlier research. In 1769, he worked on the first geological map of France. In 1771, at the age of 28, Lavoisier married the 13-year-old Marie-Anne Pierrette Paulze, the daughter of a co-owner of the Ferme. He died on May 8, 1794 by being beheaded.

Antoine Lavoisier as a Chemist

- Antoine Lavoisier is also known as “The Father of Modern Chemistry”. He was a French nobleman prominent in the histories of chemistry and biology. He stated the first version of the Law of Conversion of mass, recognized and named oxygen in 1778 and also recognized and named hydrogen in 1783. He proved that oxygen played the major role in the differences in weight associated with combustion, disproving the accepted view of the Phlogiston Theory. He helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature.

Phlogiston Theory

"Burning up". It explain processes such as combustion and the rusting of metals.

Law of Conversion of Mass

- The law of conservation of mass, also known as principle of mass conservation is that the mass of a closed system (in the sense of a completely isolated system) will remain constant over time. The mass of an isolated system cannot be changed as a result of processes acting inside the system.
- Mass cannot be created nor destroyed. Although it may be rearranged in space, and changed into different types of particles. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products.

Common Gases: General Info

Oxygen (O₂): Fire Air

- Lavoisier demonstrated the role of oxygen in the rusting of metal, as well as oxygen`s role in animal and plant respiration. Working with Pierre-Simon Laplace, Lavoisier conducted experiments that showed that respiration was essentially a slow combustion of organic material using inhaled oxygen.

-
Oxygen, which makes up about one fifth of our atmosphere, was originally given the names "fire air" and "dephlogisticated air”. It was discovered by Joseph Priestly who prepared it by heating the red oxide of mercury in 1774. However, while in modern terms the reaction was HgO + heat --> Hg +.5O_2.

Hydrogen (H₂) : Inflammable Air
- Lavoisier discovered that Henry Cavendish`s "inflammable air", which Lavoisier had termed hydrogen (Greek for "water-former"), combined with oxygen to produce a dew which, as Joseph Priestley had reported, appeared to be water. Lavoisier`s work was partly based on the research of Priestley.

Carbon Dioxide (CO₂) : Fixed Air

- Carbon Dioxide was the first gas prepared and truly characterized as a pure substance. It was studied around 1750 by Joseph Black who named it "fixed air." Information about "fixed air" was recieved through the equation:

limestone + acid --> a salt + fixed air

(modern equation: CaCO3 + 2HCL --> CaCl2 +H2O + CO2).

Pioneer of Stoichiometry
- Lavoisier`s researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products in a chemical reaction, which was a crucial step in the advancement of chemistry. He showed that, although matter can change its state in a chemical reaction, the total mass of matter is the same at the end as at the beginning of every chemical change.

Legacy

- Lavoisier`s fundamental contributions to chemistry were a result of a conscious effort. He established the consistent use of the chemical balance, used oxygen to overthrow the phlogiston theory, and developed a new system of chemical nomenclature which held that oxygen was an essential constituent of all acids (which later turned out to be erroneous).

This is a short video of the contribution of Antoine Lavoisier in Chemistry.

http://www.youtube.com/watch?v=WdjQIkvT9G0

_________________________________________________________________

“He is better known for what he has promised to the sciences than for what he as actually done for them.”

-Antoine Lavoisier

Submitted by:
Marj Mendoza
Roxy Trillanes
Eula Manibog
Isabella Meily
Djoseth Macomb

J.J Thomson

J. J Thomson(18 Dec 1856- 30 Aug 1940)

Joseph John Thomson was born in 1856 in Cheetham Hill, Manchester England. His mother, Emma Swindells, came from a local textile family. His father, Joseph James Thomson, ran an antiquarian bookshop founded by a great grandfather from Scotland. He had a brother, Frederick Vernon Thomson who is 2 years younger than him.

His early education was in a small private school. He demonstrated a great talent and interest in Science. In 1810 he was admitted to Owens College. His parents planned to enroll him as an apprentice engineer to Sharp-Stewart and co. but these plans were cut short when his father died in 1873. In 1884 he became a Cavendish Professor of Physics. One of his students was Ernest Rutherford. In 1890, he married Rose Elisabeth Paget, daughter of Sir George Edward Pager. He fathered one son named George Paget Thomson and one daughter Joan Paget Thomson.

J.J Thomson's Atomic Model:

The plum pudding model of J.J Thomson, discovered the electron in 1897 and was proposed in 1904 even before the atomic nucleus was discovered. In the model, the atom was composed of electrons (which Thomson called corpuscles) surrounded by a soup of positive charge to balance the electrons' negative charges.

* REMEMBER: NEGATIVELY CHARGED PLUMS SURROUNDED BY POSITIVE-CHARGED PUDDING

With this model, Thomson abandoned his earlier Nebular Atom hypothesis in which the atom was composed of immaterial vorticies.

In this model, the electrons were free to rotate within the blob or cloud of positive substances. These orbits were stabilized in the model by the fact that when an electron moved father from the center of the cloud, it felt a larger net positive inward force because there was more material of opposite charge inside the orbit.

The 1904 model was disproved by the 1909 gold foil experiment which was interpreted by Ernest Rutherford in 1911 to imply a very small nucleus of the atom containing a very high positive charge.

"It is the charm of physics that there are no hard and fast boundaries, that each discovery is not a terminus but an avenue leading to country as yet unexplored, and that however long the science may exist, there will still be an abundance of unsolved problems…"

-J.J Thomson

Submitted By Group 5:

Mia San Juan

Cierra Mortega

Alex Vergara

Elma Tejada

Jhoanne Sanchez

Joseph Louis Proust

Life of Joseph Louis Proust:

Angers, France - Where Joseph Proust was born on September 26, 1754

Paris, France - Where he studied chemistry and Pharmacy

University of Salamanca - Taught Chemisty

Madrid - He was the director of the royal laboratories

Jons Jacob Berzelius - Proust and Berthollet engaged in a friendly controversy over this issue, but, in the end, Proust was proved to be right.

Claude Berthollet - At the time, most chemists agreed with Claude Berthollet, who believed the composition of a compound would vary according to the amounts of reactants used to produce it

Copper Carbonate - Proust based his theory on careful analysis of copper carbonate, which he prepared in various ways.

Law of Definite Proportions:

Proust’s largest accomplishment into the realm of science was disproving Berthollet with the law of definite proportions, which is sometimes also known as Proust's Law. Proust studied copper carbonate, the two tin oxides,and the two iron sulfides to prove this law. He did this by making artificial copper carbonate and comparing it to natural copper carbonate.

It states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition.

Atoms:

are made up of 3 types of particles electrons , protons and neutrons . These particles have different properties. Electrons are tiny, very light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge. Neutrons are large and heavy like protons, however neutrons have no electrical charge. Each atom is made up of a combination of these particles.

Maegan Zablan

Romina Espuerta

Tina Silvestre

Jam Villanueva

Pamela Lopez

Ernest Rutherford

ERNEST RUTHERFORD

=================================================

~(O,O)~was born on August 30, 1871, in Nelson, New Zealand~(O,O)~

(^___^)Born on a farm in New Zealand, the second of 12 children(^____^)

(-___-)completed a degree at the University of New Zealand and began teaching unruly schoolboys(-___-)

(>__<)he became J. J. Thomson's first graduate student at the Cavendish Laboratory(>__<)

(O_O)was a British-New Zealand chemist andphysicist who became known as the father of nuclear (O_O)

physics.

(-.__.-)In early work he discovered the concept of radioactive half life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation.

(OwO)was awarded the Nobel Prize in Chemistry in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances".

(^.__.^)He died in Cambridge on October 19, 1937. His ashes were buried in the nave of

Westminster Abbey, just west of Sir Isaac Newton's tomb and by that of Lord Kelvin.

~(O.O)~was responsible for a remarkable series of discoveries in the fields of radioactivity and nuclear physics.

(^__^)He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei. Most important, he postulated the nuclear structure of the atom: experiments done in Rutherford's laboratory showed that when alpha particles are fired into gas atoms, a few are violently deflected, which implies a dense, positively charged central region containing most of the atomic mass.

\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Ernest Rutherford publishes his atomic theory describing the atom as having a central positivenucleus surrounded by negative orbiting electrons. This model suggested that most of the massof the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'

(^___^)Rutherford's model of atom was well correlated with the results of a dispersion of an a-particle by atoms of substance, but it has not explained neither the process of radiation of atoms, nor legitimacies in spectrums of radiation. According to the laws of an electrodynamics rotating around the kern the electron should radiate electromagnetic waves. As a result of radiation the natural energy of an electron should be diminished, thus the trajectory it will be figured by a spiral, and during the order 10^-8 about an electron should fall on a kern. Such deduction obtained on the basis of representations of classical physics about radiation, contradicted known stability of atoms and character of nuclear spectrums of radiation

.(^___^)British physicist Ernest Rutherford (1871-1937) has created a planetary model of atom exploring a dispersion of a-particles transiting through a thin metal foil. According to this model an atom looks like a tiny planetary system, in which the forces of an electrical attraction operate.The center of an atom is a positively charged kern. Almost all mass of an atom is focused there. Negatively charged eletrons rotate around the kern.

(^___^)The exact nature of the radiation emitted from the disintegrating elements remained a mystery until a series of papers by Ernest Rutherford in 1899 and Paul Villard in 1900. After determining that the radiation emitted from uranium was composed of two different components, Rutherford unsucessfully attempted to separate them using prisms of glass, aluminum and paraffin wax. Eventually, using two oppositely charged plates, he identified the components as positive particles (alpha particles) and lighter mass negative particles (beta particles). Villard identified a third primary type of radioactivity, gamma rays, from a radium sample. Gamma rays have no mass and possess no charge. The behavior of the three types of particles as they pass through the electric field between two charged plates is shown below.