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--------------------- 2452 - ATOMS - Michael Discovers Atoms
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- What causes the movement is the atoms in the water bouncing off the dust particles. It is called “Brownian motion” because it was first discovered in 1827 by a Scottish doctor named, Robert Brown. Robert was looking through his microscope at minute grains of pollen suspended in a liquid. The pollen was moving continuously and randomly, each one in an independent zigzag path.
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- The movement never stopped. It was observed in all types of fluids carrying any type of very small particles. It became more active in less viscous fluids and with smaller particles. It was observed for years with no sign of diminishing. They even saw it in liquid that was trapped for thousands of years inside quartz crystals. It was spontaneous, eternal, and a total mystery.
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- The process was named after its discover, Robert Brown, thus Brownian motion.
It remained a mystery for over three quarters of a century. During these 78 years it was simply defined as a condition of a fluid state.
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- Finally in 1905, guess who, Einstein, came up with a quantified theory (statistics) to explain what was going on. The disorderly movement of particles in suspension is due to the collisions with the atoms and molecules of the liquid.
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- ( I will call them atoms from here on recognizing that molecules are simply atoms chemically combined together. For example, two atoms of hydrogen and one atom of oxygen combine to make one molecule of liquid water.)
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- The higher the temperature the more active the Brownian movement. Heat gives the atoms more energy and they move faster. The dust particles are the right intermediate size between what we can see with the microscope and what we can not see, the atoms themselves.
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- Michael was using a Mattel-Intel microscope ($80) which is simply a video camera mounted on a plastic microscope and hooked up to a computer. He can magnify things 600 times. A small dust particle is 0.0001 meters, (or 10^-4 meters). Magnified 200 times it is .02 meters.
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- If you started with a penny and magnified it 200 times it would 12.5 feet tall.
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- The atoms that are hitting these particles are 10^-10 meters in size. The particles are small enough to be bounced around by the atoms yet big enough that we can see it happening.
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- Physicists have determined the size of the atoms by studying the viscosity of gases, and by measuring the diffusion of sunlight which produces the blue sky, and by studying radioactive phenomena. All these methods came up with the same numbers. One liter of any gas ( about one quart) contains 27,000,000,000,000,000,000,000 atoms (27*10^21). The size of each atom is 10^-10 meters.
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- Atoms stay together because they exert interactive forces with each other. If the interactive forces are smaller than the kinetic forces of motion than the atoms stay close to their initial position and are said to be solid, ice is a solid.
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- If we add heat and the atoms gain kinetic energy of motion that is greater than their interactive forces they move about more freely and they become a liquid. If the heating continues, the atoms gain even more energy, move even more freely and become a gas, water vapor is a gas.
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- The energy of each atom becomes greater the higher the temperature. Atoms follow a zigzag path because they keep colliding with each other and bouncing off in a new direction.
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- When atoms bounce off the walls of a container we call that gas pressure. Gas pressure is higher if more atoms are added to the container, or if the container is raised to a higher temperature. Either way more atoms are bouncing off the sides of the container and the pressure is higher.
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- When you are traveling down the highway at 65 mph your 4000 pound SUV is suspended from the road by the nitrogen and oxygen atoms that are colliding with the walls of your rubber tires. The air is compressed into the tires in order to increase the pressure. If the tires get warm driving over the hot asphalt the tire pressure will increase even more.
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- The size of an atom is 10^-10 meters. At room temperature an oxygen atom has a velocity of 400 meters / second, 385 miles per hour. If the atom could travel in a straight line without hitting anything it could go from Santa Rosa to San Francisco in 200 seconds ( 3.35 minutes) If it kept going it would be in Los Angeles in just under one half hour.
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- But, that is not what happens. There are so many atoms in so little space they are constantly colliding with each other. The free path between collisions averages 10^-7 meters.
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- This means that in one centimeter distance traveled the atom has had 100,000 collisions and redirections making for a very complicated zigzag path. At the end of this zigzag journey it will only have moved from its original position by 3*10^-5 meters.
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- The length of a grain of salt is 10^-5 meters. That poor atom is having 4,000,000,000 collisions every second.
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- I am trying to make an engineer out of him.:>) What do you think Michael? Are you ready to become an engineer with a biology degree? Pond water is biology.
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- Grandpa,
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- First written December 9, 2004
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- October 19, 2019. 76 2452
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--------------------- Saturday, October 19, 2019 -------------------------
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