Most of the following information are obtained by keying in at Google Search “size of” followed by the thing you want to know the size of.

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Cool !!! check this out! The most comprehensive comparison I have seen! :

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Below taken from: http://www.drgreene.com/qa/bacteria-vs-viruses

What’s the difference between bacteria and viruses?

Viruses are tiny geometric structures that can only reproduce inside a living cell. They range in size from 20 to 250 nanometers (one nanometer is one billionth of a meter). Outside of a living cell, a virus is dormant, but once inside, it takes over the resources of the host cell and begins the production of more virus particles. Viruses are more similar to mechanized bits of information, or robots, than to animal life.

Bacteria are one-celled living organisms. The average bacterium is 1,000 nanometers long. (If a bacterium were my size, a typical virus particle would look like a tiny mouse-robot. If an average virus were my size, a bacterium would be the size of a dinosaur over ten stories tall. Bacteria and viruses are not peers!) All bacteria are surrounded by a cell wall. They can reproduce independently, and inhabit virtually every environment on earth, including soil, water, hot springs, ice packs, and the bodies of plants and animals.

Most bacteria are harmless to humans. In fact, many are quite beneficial. The bacteria in the environment are essential for the breakdown of organic waste and the recycling of elements in the biosphere. Bacteria that normally live in humans can prevent infections and produce substances we need, such as vitamin K. It is estimated that 1000 to 2000 different species of bacteria live in the human gut and skin. It is also impressive to know that there are at least ten times as many bacteria as human cells living in the human body. Bacteria in the stomachs of cows and sheep are what enable them to digest grass. Bacteria are also essential to the production of yogurt, cheese, and pickles. They are now also commonly included as probiotic dietary supplements. Some bacteria cause infections in humans. In fact, they are a devastating cause of human disease.

Above taken from: http://www.drgreene.com/qa/bacteria-vs-viruses

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Below taken from: http://kids.britannica.com/comptons/article-197138/bacteria

The Size of Bacteria

Bacteria are smaller than other cells, but larger than viruses. Bacteria are measured in units of length called micrometers, or microns. One millimeter is equal to 1,000 microns; it takes about 25,000 microns to make up one inch (2.5 centimeters). Some bacteria measure only one half a micron. Thiomargarita namibiensus, a bacterium that lives buried in ocean sediment, may measure as much…

bacteria... (75 of 17727 words)

Above taken from: http://kids.britannica.com/comptons/article-197138/bacteria

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Below taken from: http://en.wikipedia.org/wiki/Molecule#Molecular_size

Molecular size

Most molecules are far too small to be seen with the naked eye, but there are exceptions. DNA, a macromolecule, can reach macroscopic sizes, as can molecules of many polymers. The smallest molecule is the diatomic hydrogen (H2), with a length of 0.74 Å.[5] Molecules commonly used as building blocks for organic synthesis have a dimension of a few Å to several dozen Å. Single molecules cannot usually be observed by light (as noted above), but small molecules and even the outlines of individual atoms may be traced in some circumstances by use of an atomic force microscope. Some of the largest molecules are macromolecules or supermolecules.

Above taken from: http://en.wikipedia.org/wiki/Molecule#Molecular_size

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Following taken from: http://trshare.triumf.ca/~safety/EHS/rpt/rpt_1/node7.html

Size of the Atom

The nucleus of the atom has a diameter of about meter, whereas the atomic diameter is about meter. This means that the nucleus has a diameter 10,000 times smaller than the atom. The great amount of empty space in an atom can be illustrated by the following analogy.

Imagine the nucleus to be the size of a golf ball. Then on this scale the first electron shell would be about one kilometer from the golf ball, the second shell about four kilometers, the third nine kilometers and so on. If you find that hard to visualize then try this. The period at the end of this sentence, (depending on your monitor and the font you are using), is probably about 1/2 a millimeter in diameter. If that period represents the nucleus then the electrons in the first shell would be orbiting with a diameter about 50 meters around you. in fact, the actual diameter of an atom is very small and it would require some two hundred million of them side by side to form a line a centimeter long.

Noel Giffin

Tue Jan 23 14:53:50 PST 1996

Above taken from: http://trshare.triumf.ca/~safety/EHS/rpt/rpt_1/node7.html

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Following taken from: http://www.newton.dep.anl.gov/askasci/phy00/phy00494.htm

Ask A Scientist

Physics Archive

Electron vs Quark Size

2002067

name Tania N.

status educator

age 30s

Question - If a proton/neutron is very much larger than an electron,

is a quark bigger or smaller than an electron? -- Question from one of

my little year seveners. (grade~2)

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Tania,

A quark has never demonstrated any measurable size. Like an electron, it is

a "fundamental particle", one of the few particles from which all else is

made. The size of a proton or neutron comes from the motion of the quarks

as they orbit around each other, sending energy and particles(called mesons)

back and forth between each other. The three quarks are the primary

particles of a proton/neutron, the particles that identify the proton or

neutron for what it is. Still, the proton/neutron is essentially a cloud of

motion with low energy particles flashing in and out of existence all the

time. It is this cloud of motion that gives the proton/neutron its size.

Dr. Ken Mellendorf

Physics Instructor

Illinois Central College

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It takes "seveners" to ask those questions we wish we had asked in graduate

school.

The "size" of atomic and sub-atomic particles loses its meaning, because

these "particles" behave as though they are waves, or wave packets. So

"size" becomes kind of "squishy". However, with that caveat, the "classical"

radius of a "free" electron is taken to be about 3x10^-15 meters, and the

"classical" radius of a "free" proton is taken to be about 1x10^-15 -- only

about 1/3 the radius of the electron. However, the "classical" radius of a

hydrogen atom consisting of 1 proton and 1 electron, the Bohr radius, is

about 5x10^-9 meters about one million times the radius of either component

particle.

I do not know that anyone really thinks of quarks and other sub atomic

particles as having a particular "size", in fact their masses are usually

given in energy units of c^2 from the Einstein relation E = mc^2.

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Above taken from: http://www.newton.dep.anl.gov/askasci/phy00/phy00494.htm

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