Transcript The Atom - TypePad

THE ATOM
Chapter 11 Section 2
What is an atom made of?
1)
Inside the Nucleus



2)
Atomic Mass Unit – unit of mass that describes the
mass of an atom or molecule.
Protons = POSITIVE charge (1 proton = 1amu.)
Neutrons = NEUTRAL charge (1 neutron = 1amu.)
Outside the Nucleus:

Electrons = NEGATIVE charge – found in the electron
cloud (levels)
Parts of an Atom
PROTON
+ N
+ N
ELECTRON
CLOUD
NUCLEUS
NEUTRON
ELECTRON
Electrical Charges of an Atom
Equal #’s of protons (+) and electrons (-) will cancel
each other out to create a NEUTRAL atom.
…more protons than electrons = POSITIVE atom
…more electrons than protons = NEGATIVE atom
PROTON
ELECTRON
NEUTRON
NEUTRAL ATOM
NEGATIVE ATOM
Terms to Know…
Atomic Number – tells you the number of protons in
and atom.
Mass Number – the sum of the numbers of protons
and neutrons in the nucleus of an atom.
+
N N
N
+
+
-
Atomic Number = 3
Mass Number = 6
You Try!...
ATOM #1
ATOM #2
-
+
+
N
-
Atomic Number: ______
Mass Number: _______
N
+
-
Atomic Number: ______
Mass Number: _______
Terms to Know…
Isotope
…an atom that has the same number of protons (or
the same atomic #) as other atoms of the same
element, but has a different number of neutrons (and
thus a different atomic mass)