Isotopes. Isotopes are atoms that have the same number of protons but different numbers of neutrons...
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Transcript of Isotopes. Isotopes are atoms that have the same number of protons but different numbers of neutrons...
Isotopes
Isotopes• Isotopes are atoms that have the same
number of protons but different numbers of neutrons
• Most elements in the first two rows of the periodic table have at least 2 isotopes with one being more common than the other
• In nature, elements are almost always found as a mixture of isotopes
Hydrogen Deuterium Tritium
•For example, the most common isotope of hydrogen has no neutrons at all
•There's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons.
Neutron
Proton
Isotopes of Hydrogen
Most common isotope
• To identify an isotope more specifically, chemists add a number after the elements name.
ex. Carbon-11 Carbon-12 Carbon-14• This number is called the isotope’s mass number and
is the sum of the isotope’s number of protons and neutrons.
• For example, an atom with 17 protons and 20 neutrons has a mass number of 37.
More fun with Isotopes
Q. What is the mass of the Nitrogen isotope with 7 protons and 12 neutrons?
A. Nitrogen-19
iodine-128
potassium-40
75
21
53
19
53
19
Atom Protons Electrons Neutrons
Examples
Isotope Symbols
141
56
Mass number
Atomic number
ChargeBa2+
How many protons, neutrons, and electrons are present?
5626STEP 1: The atomic number in the lower left corner = 26 protons. The difference between the mass number and the atomic number is 56 – 26 = 30 neutrons
STEP 2: The charge on the ion, 2+ shows us that there are 2 more protons than electrons, indicating that there are 24 electrons.
Fe 2+
Isotope Symbols
141
56
Mass number
Atomic number
ChargeBa2+Step 1) 141- 56= 85 neutronsStep 2) 56 electrons -2 = 54 electrons