atoms of the same element with different numbers of neutrons. what has changed if there is a...
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WHAT IS AN ISOTOPE?
Atoms of the same element with different numbers of neutrons. What has changed if there is a different
number of neutrons. HINT: look at your periodic tables. Something must have changed.
WHAT IS AN ISOTOPE
If you have a different number of neutrons, that means your atomic mass has changed. Remember that atomic mass = neutrons +
protons
THE NUMBER OF PROTONS NEVER CHANGES. Why doesn’t this number ever change?
WHAT IS AN ISOTOPE?
If you change the number of protons you now have a different element. EX: If you have an atom of Ne (Neon) with
11 protons now.. You actually would have an atom of Na (Sodium)
TWO SODIUM ATOMS
Sodium with 11 protons and 12 neutrons.
** This is what we see on the periodic table.
Sodium with 11 protons and 13 neutrons.
** Different from periodic table
HOW DO WE SHOW ISOTOPES?
X: element symbol
A: Mass Number# protons + # neutrons in the nucleus
Always larger than Z
Z: Atomic number
#protons
A, X, and Z are very important
to remember
!
TRY IT IN YOUR NOTES
What is the element?
How many protons are in the element?
What is the elements atomic mass?
Na
23
11
TRY IT IN YOUR NOTES
What is the element? Sodium
How many protons are in the element? 11
What is the elements atomic mass? 23
Na
23
11
TRY IT IN YOUR NOTES
What is the element?
How many protons are in the element?
What is the elements atomic mass?
Cl33
17
TRY IT IN YOUR NOTES
What is the element? Chlorine
How many protons are in the element? 17
What is the elements atomic mass? 33
Cl33
17
HOW ELSE DO WE SHOW ISOTOPES?
Sodium-23
Mass Numbe
r
Element
Name
** This is what we see on the periodic table
Write the isotope symbol for the chemical element that has 6 protons and 8 neutrons (write the symbol both ways)
Write the isotope symbol for the chemical element that has 6 protons and 8 neutrons (write the symbol both ways)
Carbon – 14 C14
6
Write the isotope symbol for the chemical element that has 17 protons and 16 neutrons
Cl or Chlorine-3317
33
How many protons are in the isotope 54Cr? (Chromium-54)
24 just like all Chromium Protons NEVER CHANGE
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