1. Mass number of Lithium-7: 7
Explanation:
- The atomic number of an element is equal to the number of protons inside its nucleus
- The mass number of an element is equal to the number of protons+neutrons inside its nucleus
The nomenclature "Element-X", where X is the number of protons+neutrons, is used to indicate the mass number of the isotope. Therefore, an isotope of LIthium-7 has a mass number of 7.
2. An isotope of lithium-8 contains 5 neutrons
Explanation:
Lithium is the third element of the periodic table, so its atomic number is 3, which means that it has 3 protons.
In this problem, we have an isotope of lithium-8, which means that it has a mass number of 8: so, the sum of neutrons+protons in its nucleus is 8:
[tex]p+n=8[/tex]
where p is the number of protons and n the number of neutrons. However, we also know that for lithium p=3, so we can find the number of neutrons:
[tex]n=8-p=8-3=5[/tex]
The isotope of Lithium-7 has a mass number of 7. And the isotope of Lithium-8 has 5 neutrons.
Given data:
The number of protons in a lithium-7 isotope is, 3.
The mass number of an element is equal to to the number of protons inside its nucleus. Mathematically,
Mass number = number of protons + number of neutrons
Mass number of Lithium-7:
The nomenclature of "Element-X", where X is an abbreviation to indicate the mass number of the isotope.
Therefore, an isotope of Lithium-7 has a mass number of 7.
Number of neutrons in an isotope of lithium-8:
Lithium-8 has the mass number of 8. And we know that,
Mass number = number of protons + number of neutrons
Lithium is the third element of the periodic table, so its atomic number is 3, which means that it has 3 protons.
Then,
8 = 3 + number of neutrons
number of neutrons = 8 - 3
number of neutrons = 5
Therefore, an isotope of Lithium-8 has 5 neutrons.
Learn more about the mass number here:
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