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Isotope Notation Isotope Notation uses a symbol to convey information about an isotope of a particular element. 23 Na 11.

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Presentation on theme: "Isotope Notation Isotope Notation uses a symbol to convey information about an isotope of a particular element. 23 Na 11."— Presentation transcript:

1 Isotope Notation Isotope Notation uses a symbol to convey information about an isotope of a particular element. 23 Na 11

2 Isotope Notation Is the # of protons (p + ) in the atom AND 23 Na 11 Atomic Number The # of electrons (e - ) IF the atom is electrically neutral ( i.e., not an ion). This number is on the periodic table. Mass Number Is the number of protons plus the number of neutrons. This number tells us the kind of isotope. This number is NOT on the periodic table.

3 For this isotope 11 p e - 0 net charge Isotope Notation 23 Na Na + 11 For this isotope 11 p e net charge

4 Isotope Notation 23 Na 11 Atomic Number The # of protons + the # of neutrons Calculate the number of neutrons for this isotope. 23 (neutrons + protons) - 11 protons = 12 neutrons Mass Number

5 Atomic Mass Is the weighted average mass of all the isotopes of one element in atomic mass units (amu). In other words, it is the mass of one average atom*. Two measurements are needed in order to calculate this average. 1.The percent abundance (% abundance,) also known as how often the isotope occurs in nature. 2.The mass of one atom of one isotope. Atomic mass is also known as Weighted Average Atomic Mass Average Atomic Mass

6 Atomic Mass Here is the formula you need to know in order to calculate the average atomic mass. Average Atomic Mass = [(Mass of Isotope 1) x (% abundance of Isotope 1)] + [(Mass of Isotope 2) x (% abundance of Isotope 2)] + and so on for the 3 rd and remaining isotopes. The average atomic mass is written on the periodic table

7 Mass Number vs. Atomic Mass Mass number = # protons + # neutrons (This number is specific for one isotope.) Atomic mass = weighted average mass of all the isotopes of one element in atomic mass units (amu). (The atomic mass is on the periodic table.)


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