Download The Atom

The Atom
How big is an Atom?
 The
average size atom (Al) is
about 0.00000003 cm.
 It would take a stack of 50,000
aluminum atoms to equal the
thickness of a sheet of
aluminum foil.
That’s
Small!!!!
What’s Inside an Atom?
 An
atom is made up of a team
of three players: protons,
neutrons, and electrons
 They each have a charge,
mass, and a location
Protons...
 Charge:
positive
 Mass: 1 amu (atomic mass unit)
 Location: Nucleus
Neutrons...
 Charge:
none
 Mass: 1 amu (atomic mass unit)
 Location: Nucleus
Electrons...
 Charge:
negative
 Mass: almost zero
 Location: electron clouds
Electrons vs Protons
 The
electron’s negative charge
is the same size as a proton’s
positive charge.
 They cancel each other out:
 +1 -1 = 0
 Atoms like to have 0 charge.
Questions...
 What
particles are in the
nucleus?
 Explain why atoms are neutral.
 Why do scientists say that most
of the mass of an atom is
located in the nucleus?
How Do Atoms of Different
Elements Differ?
 Lets
compare a Hydrogen atom
and a Helium atom…
Hydrogen...
 Draw
one proton.
 Draw a circle around the
proton.
 Place one electron on the circle.
 You have just created a
hydrogen atom!
 Hydrogen has no neutrons.
Helium
 Draw
two protons and two
neutrons all together.
 Draw an electron orbit around
them.
 Place two electrons on the
orbit.
 You have just created a helium
atom!!!
What is different?
 The
two different elements
have different numbers of
electrons, protons, and
neutrons.
 OK...
Are all atoms of an element
the same?
 Draw
another Hydrogen atom,
but this time add a neutron.
 It is still Hydrogen because it
has only one proton, but it has
more mass in the nucleus.
 It is called an isotope.
What is an Isotope?
 Isotope
- atoms that have the
same number of protons but
have different numbers of
neutrons.
 Some isotopes are radioactive.
 Otherwise they are mostly the
same as the regular atom.
How can you tell one
isotope from another?
 By

their mass numbers.
mass number = protons + neutrons.
 Different
isotopes will have
different mass numbers
because they have different
numbers of neutrons.
Let’s see...
 Hydrogen-1
has 1 proton and 0
neutrons.
 Mass Number = 1
 Hydrogen-2 has 1 proton and 1
neutron.
 Mass Number = 2
Questions…
 List
the charge, location, and
mass of each particle.
 Determine the number of
protons, electrons, and
neutrons in aluminum-27.