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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
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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 Isotopes of Hydrogen • 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. Most common isotope Neutron Proton
More fun with Isotopes • 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.
Q. What is the mass of the Nitrogen isotope with 7 protons and 12 neutrons? A. Nitrogen-19
Examples AtomProtonsElectronsNeutrons 53 19 75 21 iodine-128 potassium-40 53 19
Isotope Symbols Mass number Ba2+ 141 Charge 56 Atomic number
How many protons, neutrons, and electrons are present? 56 26 STEP 1: The atomic number in the lower left corner = 26 protons. The difference between the mass number and the atomic number is 56 – 26 = 30neutrons 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 Mass number Ba2+ 141 Charge 56 Atomic number Step 1) 141- 56= 85 neutrons Step 2) 56 electrons -2 = 54 electrons