12. Describe Proton
• Protons are positively charged particles
found in the atomic nucleus. Protons were
discovered by Ernest Rutherford..
• Experiments done in the late 1960's and
early 1970's showed that protons are
made from other particles called quarks.
Protons are made from two 'up' quarks
and one 'down' quark.
14. Describe Neutron
• Neutrons are uncharged particles found in
the atomic nucleus. Neutrons were
discovered by James Chadwick in 1932.
• Experiments done in the late 1960's and
early 1970's showed that neutrons are
made from other particles called quarks.
Neutrons are made from one 'up' quark
and two 'down' quarks.
16. Describe Electron
Electrons are negatively charged particles
that surround the atom's nucleus.
Electrons were discovered by J. J.
Thomson in 1897.
Electrons determine properties of the atom.
Chemical reactions involve sharing or
exchanging electrons.
18. Describe Nucleus
The nucleus is the central part of an atom. It
is composed of protons and neutrons.
The nucleus contains most of an atom's
mass.
It was discovered by Ernest Rutherford in
1911.
20. Describe Quark
• Believed to be one of the basic building blocks
of matter. Quarks were first discovered in
experiments done in the late 1960's and early
1970's.
• Three families of quarks are known to exist.
Each family contains two quarks. The first family
consists of Up and Down quarks, the quarks that
join together to form protons and neutrons.
• The second family consists of Strange and
Charm quarks and only exist at high energies.
• The third family consists of Top and Bottom
quarks and only exist at very high energies.
24. What is the Electron Cloud Model?
Model of the atom pictures the electrons moving
around the nucleus in a region called an electron
cloud.
The electron cloud is a cloud of varying density
surrounding the nucleus. The varying density
shows where an electron is more or less likely to
be. Atoms with electrons in higher energy levels
have additional electron clouds of different
shapes that also show where those electrons
are likely to be.
For more information, click here:
http://regentsprep.org/Regents/physics/phys05/catomodel/cloud.htm
