Transcript Nurse Shark (Ginglymostoma cirratum)

PS-2.2 Illustrate the fact
that the atoms of elements
exist as stable or unstable
isotopes.
Opener- Write the chart & fill it in
Protons
Symbol
Mass
(heavy/light)
Location
Charge
Does it
affect ID?
Does it
affect mass?
Does it
affect
volume
Neutrons
Electrons
Opener
•Study
st
1
15 elements
•Turn in hw ½ sheet
into the front basket
Opener 1/23/07
* atomic number – found on the
periodic table, = # p+, identifies the
atom
* mass number - # protons + #
neutrons
* atomic mass - weighted average of
the masses of the naturally
occurring isotopes of an element.
Opener 1/23/07
* Isotope – atoms of the same element
with the same # p, different # neutrons
* nuclear decay - a nuclear reaction that
involves emission of energy or particles
from the nucleus, resulting in a more
stable nuclear environment
* radiation - describe the particles and/or
energy that are emitted during nuclear
decay. (Alpha, and beta particles, and
gamma rays)
Atomic Number
• equal to the number
of protons, always
the same for a given
element
• found on the
periodic table
• since it is the same
for all atoms of
that element, it is
always a whole
number.
47
Ag
Silver
Atomic
107.87
number
Atomic
number
Mass Number
• atoms of the same element may have
different numbers of neutrons
• the sum of that atom’s protons and
neutrons
• can only be found on the periodic
table for stable atoms, cannot be
found on the periodic table for an
isotope
Atomic Mass
• the weighted average
of the masses of the
naturally occurring
isotopes of an element
• found on the periodic
table
• it is an average, so
usually not a whole
number
17
Ag
Silver
107.87
Atomic mass
Atomic Mass
Isotopes
• two or more atoms of the
same element having the
same number of
protons but different
numbers of neutrons (and
therefore different
masses)
• different numbers of
neutrons, so they have
different mass numbers
• Brittany
Isotopes
Carbon-14
• Atomic # 6
• Atomic Mass
14…..
• Mass #
14
• # protons
6
• # neutrons
8
• # electrons
6
Carbon-16
•
•
•
•
•
•
Atomic # 6
Atomic Mass
Mass #
# protons
# neutrons
# electrons
16…..
16
6
10
6
Isotope Notation
(mass #)
12
(Atomic #)
6
(Symbol)
C
(Symbol)
C - 12
(Mass #)
Unstable isotopes
• In order for a nucleus to be
stable, there must be enough
neutrons present to block the
repulsive forces among the
protons
• An unstable isotope of an
element is radioactive (gives
off radiation)
Due to the unstable condition of the
nucleus, radioactive isotopes undergo
nuclear decay
– Nuclear decay is a nuclear reaction that involves
emission of energy or particles from the
nucleus, resulting in a more stable nuclear
environment
– Nuclear decay occurs naturally in many elements
that are common on earth and there is always
some radiation present in every environment
– Radiation is the term used to describe the
particles and/or energy that are emitted during
nuclear decay (Alpha, and beta particles, and
gamma rays)
Review
What is defined as the sum
of the p+ and the n0 ????
Review
What defines the element??
Review
What is the weighted
average of the masses
of the naturally
occurring isotopes of an
element???
Review
An isotope is two atoms
of the same element
with the same # of
___ but a different #
of _____ ????
Review
What are the two ways
that we could write
isotopic notation for
the isotope Carbon - 18
????
Review
In order for a nucleus
to be stable, there
must be enough ___
present to block the
repulsive forces of the
_____ ????
Review
What is nuclear
decay ????
Review
What are the particles
or energy emitted
during nuclear decay
called????
Review
What determines if
an isotope will be
stable or
unstable?????