Atomic Nucleus - Physical Chemistry
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Which atomic symbol represents a period five transition metal that has 42 electrons when it forms a 
cation?
Which atomic symbol represents a period five transition metal that has 42 electrons when it forms a
Transition metals extend from groups 3 through 12 and periods 4 through 7. Ru, in its neutral state, has 44 electrons. Therefore, when it becomes a 
cation, it will have 42 electrons.
Transition metals extend from groups 3 through 12 and periods 4 through 7. Ru, in its neutral state, has 44 electrons. Therefore, when it becomes a
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How many neutrons are present in the nucleus of one atom of 
?
How many neutrons are present in the nucleus of one atom of
From the periodic table, we find that the atomic number, i.e., the number of protons in the nucleus of 
is 15. Given that the mass number is 32, and recalling the formula which relates mass number to the number of neutrons and protons: 
, we find that the number of neutrons in the nucleus of one atom of 
is 17.
From the periodic table, we find that the atomic number, i.e., the number of protons in the nucleus of
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What is the mass number, atomic number, and charge, of the isotope of an atom that contains 34 protons, 36 neutrons, and 36 electrons?
What is the mass number, atomic number, and charge, of the isotope of an atom that contains 34 protons, 36 neutrons, and 36 electrons?
The atomic number is equal to the number of protons in the element, so from the periodic table, we find that the element with atomic number 34 is selenium. Since 
, we calculate that the mass number is 70. Lastly, there are two more electrons than protons, so the charge will be 
.
The atomic number is equal to the number of protons in the element, so from the periodic table, we find that the element with atomic number 34 is selenium. Since
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