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What are the building blocks of matter?
What are the most fundamental building blocks of all
matter -- the pieces of matter that make up everything from
flowers to people to galaxies and cannot be broken down
into anything smaller?
Model
of a Helium Atom
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This
helium atom is not drawn to scale. In a real atom, the
protons and neutrons are far larger than quarks and
electrons, and there would be much more empty space.
In fact, if this atom were the size of a large city,
each proton and neutron would be the size of a person,
and each quark and electron would be smaller than a
tiny freckle.
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Scientists
once thought the most fundamental building block of matter
was a particle called the atom. Now we know that the atom
is made of many smaller pieces, known as subatomic particles.
Every atom contains a central core called the nucleus, made
of particles called protons and neutrons. The nucleus is
surrounded by mostly empty space, except for very tiny particles
called electrons that orbit the nucleus. Recently, scientists
have discovered that protons and neutrons are made of smaller
particles known as quarks.
Today, physicists don't know of anything smaller than quarks
and electrons, but they don't know for sure whether these
are the simplest building blocks of matter.
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