The Brownian Motion

In 1827, Robert Brown observed through the microscope that some pollen grains suspended in water were moving constantly and randomly in no specific direction. The Brownian Motion was observed not only in pollen grains but also in other small particles such as dust and smoke particles. When smoke particles in the air were view through a microscope under the bright light, they were seen as bright points moving about constantly and randomly with no specific directions in the air. It was aboout eighty years later, 1905 that Albert Einstein came up with a theory to explain Brownian Motion. Another scientist Jean Baptiste Perrin, carried out experiments to show that Einstein's theory could better explain the movement of particles. Einstein explained that the pollen grains in the water moved constantly and randomly because they were bombarded all around by water particles which themselves were moving constantly and randomly. Remember that although the pollen grains are microscopic, the water particles are even smaller and cannot be observed with a normal microscope. Similarly, tiny air particles which are moving constantly and randomly bombard or hit the larger smoke or dust particles in the air in all directions, causing the jittery motions of the smoke and dust particles.

References:

http://en.wikipedia.org/wiki/Brownian_motion

http://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/brownian/brownian.html

http://http//xanadu.math.utah.edu/java/brownianmotion/1/

Definition of The Particulate Model of Matter

What is the Particulate Model of Matter? Based on the evidence gathered from observations and experiments, scientists proposed a model which explains the nature of matter. This model is called the Particulate Model of Matter. Tje Particulate Model of Matter states that matter is made of tiny discrete particles, which are in constant and random motion. About 2500 years ago, the greek philosopher, Democritus (460 B.C. - 370 B.C), proposed that if one were to break up matter into smaller and smaller pieces, there would come to a point when it could no longer be divided further. He called this smallest indivisible bit of matter 'atom'. On the other hand, another famous philosopher, Aristotle (384 B.C - 322 B.C), proposed that matter has a continuous composition and that it can be broken down into smaller and smaller pieces forever. After the Brownian Motion ( particles in pollen grains that moved constantly and randomly in no specific directions ) was explained by Elbert Einstein and demonstrated by Jean Baptiste Perrin, in other words, Democritus' proposal that matter is made up of tiny particles is indeed right.

References:

http://http//mackenzie.vsb.bc.ca/G7Science/117.pdf

http://http//wiki.answers.com/Q/Particle_model_of_matter

Osmosis

Osmosis is the diffusion of water through a semi-permeable membrane. More specifically, it is the movement of water across a semi-permeable membrane from an area of high water potential (low solute concentration) to an area of low water potential (high solute concentration). It is a physical process in which a solvent moves, without input of energy, across a semi-permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations. Osmosis releases energy, and can be made to do work, as when a growing tree root splits a stone. For example, if you put an animal cell into a beaker of water and observe it after a few hours, the cell would likely swell up and finally burst. This is because, Osmosis has occured and made the water pass through the semi/partially permeable membrane of the animal cell, causing it to swell up as water has been absorbed and finally bursts.

Reference:

http://http//www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.html

http://http//en.wikipedia.org/wiki/Osmosis

Diffusion

What is Diffusion? Diffusion is the process in which molecules from a region of higher concentration to one of lower concentration by random molecular motion. The result of diffusion is a gradual mixing of material. In a phase with uniform temperature, absent external net forces acting on the particles, the diffusion process will eventually result in complete mixing or a state of equilibrium. Basically, it is the movement of molecules from an area of high concentration to a lower area. Molecular diffusion is typically described mathematically using Fick's laws. For example a cube of sugar being dropped into a beaker containing water. The sugar molecules, being the region of higher concentration, diffused into the water, being the region of lower concentration. Now the sugar has been dissolved into the water, or as we might say, diffused. If you want to view the video demonstration of diffusion please visit this site: http://http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

References:
http://http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
http://http://en.wikipedia.org/wiki/Molecular_diffusion
Glossary:
Fick's laws of diffusion describe diffusion and can be used to solve for the diffusion coefficient, D. They were derived by Adolf Fick in the year 1855.

What are Atoms, Molecules and Ions ?

In mathematical logic, an atomic formula (also known simply as an atom) is a formula with no deeper propositional structure, that is, a formula that contains no logical connectives or equivalently a formula that has no strict subformulas. Atoms are thus the simplest well-formed formulas of the logic. Compound formulas are formed by combining the atomic formulas using the logical connectives. In a sense, the atoms are like the 26 letters of the alphabet that join together in different combinations to form the immense number of words in our language. molecule is defined as a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules. An ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.

References:

http://http//en.wikipedia.org/wiki/Ion

http://http//en.wikipedia.org/wiki/Molecule

http://http//wps.prenhall.com/esm_brown_chemistry_9/0,4647,169289-,00.html

http://en.wikipedia.org/wiki/Atom_(logic)

Glossary:

Covalent - Very strong

Polyatomic Ions - two or more atoms covalently bonded or of a metal complex that can be considered as acting as a single unit in the context of acid and base chemistry or in the formation of salts.