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Questions and Answers

Questions are an important part of the scientific process and, over the years, hundreds of people have sent their questions to us. Listed below are some of the most common, and most interesting, questions visitors to our site have asked. A special thanks to all of the staff members who have taken the time to help answer these questions. Your efforts are greatly appreciated!

Atoms, Elements and Molecules

Since Jefferson Lab is a nuclear physics research facility, it isn't surprising that we're often asked questions about atoms. We've selected the most common questions from the main archive and have listed them here for your convenience.

Complete Question Archive

Atoms and Matter

What is an atom? What are atoms made of?

How do I make a model of an atom?

What is one example of indirect evidence that scientists use to study an atom?

What is an element? How many elements are there?

What is the difference between atoms and elements?

What is the simplest way of explaining what atoms, elements, compounds and mixtures are?

What is a mixture?

What is the difference between a compound and a molecule?

I am not clear on what a molecule is. If water is a molecule, is it also a compound because the hydrogen and oxygen have been chemically combined? If so...

What is the biggest atom? The smallest atom?

How do atoms form?

Does gravity affect atoms?

Can you crush atoms?

What are the components of an atom? How much does each atom weigh?

Is there an atom that does not have neutrons?

What is the modern view of the structure of the atom? How are the protons different from neutrons? What are the differences between protons and electrons?

What kind of charge does a proton have? And what kind of charge does a neutron have?

Why do protons and neutrons stay together in the nucleus?

How many times bigger is a proton than an electron?

Why are electrons so far away from the nucleus of an atom?

How many electrons fit in each shell around an atom?

How are electrons placed in shells around the nucleus?

How do I read an electron configuration table?

What holds an electron revolving around the nucleus? Why don't they just go zooming around everywhere?

What keeps the electrons revolving around the nucleus of an atom?

How much of an atom is empty space?

If atoms are made up mostly of "empty space," what is in that empty space?

If atoms are 99.999999999999% empty space then why don't things pass right through them?

If all physical things are made of atoms, then why do different physical things have different physical properties? Like why is wood hard and rubber soft?

How fast do electrons move?

What do we use to measure mass?

Is matter everywhere?

If everything around us is matter, what about germs?

How do you prove air is matter?

Why is matter not being created at the present time, nor being destroyed?

Why don't atoms weigh anything?

What are the exact relative masses of protons, neutrons and electrons?

If different types of quarks have different masses, then why are protons and neutrons said to have the same mass, when they have different compositions of quarks?

What is plasma?

How do you know plasma is real if you can't see it?

What is the smallest particle of matter known?

Could there be anything smaller inside of an electron or inside of a neutron or a proton?

How many quarks are in a proton? How many quarks are in a neutron?

What kinds of quarks are protons and neutrons made of? What was the old name for the Top and Bottom quark?

What is the charge of an up quark and the charge of a down quark? How many quarks make up a proton and a neutron?

Are quarks confineable for study?

Is vacuum matter? What are ten things that are not matter?

What is a vacuum? Is it matter?

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For questions about this page, please contact Steve Gagnon.