Download Chapter 17 sections 1 and 2

Chapter 17
Sections 1 and 2
Atomic Components
• Atom– smallest piece of matter that still
retains the property of the element
• Nucleus—the small, positively charged core of
an atom where the protons and neutrons
reside
• Protons—positively charged particles
• Neutrons—neutrally charged particles
• Electrons—negatively charged particles
Quarks
• Small particles that make up protons and
neutrons
• Scientists theorize that an arrangement of
three quarks held together with the strong
nuclear force produces a proton. Another
arrangement of three would produce a
neutron.
• To find quarks, scientists accelerate charged
particles to tremendous speeds and then force
them to collide with protons. This causes the
proton to break into smaller pieces known a
quarks.
• Scientists use inference to identify the
subatomic particles and to reveal information
about each particle's inner structure.
Models
• There have been 5 accepted models of the
atom.
• Dalton/ Democritus
• Thomson
• Rutherfod
• Bohr
• Electron Cloud
Dalton’s Model
• Dalton’s model was that
of a solid sphere
Thomson’s Model
• Atoms contain small,
negatively charted
particles
• He said these electrons
(pictured in blue) were
evenly embedded
throughout a positively
charged sphere, much
like chocolate chips in a
ball of cookie dough.
Rutherford’s Model
• Almost all the mass of
an atom—and all it’s
positive charges—were
concentrated in a
central atomic nucleus
surrounded by
electrons.
Bohr’s Model
• Electrons traveled in
fixed orbits around the
atom’s nucleus.
Chadwick
• He didn’t create a new
model just expanded
what his teacher
Rutherford did.
• He concluded that the
nucleus contained
positive protons and
neutral neutrons.
• This worked with Bohr’s
model.
Modern Model
• Electrons do NOT follow
a fixed orbit, but tend
to occur more
frequently in certain
areas around the
nucleus at any given
time
Atomic number and mass
• Atomic number is the number of protons in an
atom.
• By looking at the atomic number you can
figure out how many neutrons there are as
well. Neutrons equal the protons unless it is
an isotope
• An isotope is an atom that has a different
number of neutrons.
• Atomic mass or mass number is the sum of
the number of protons and neutrons in the
nucleus.
• IF you know the mass number you can
calculate the number of neutrons the
equation is:
• Number of neutrons = mass number – atomic
number