How to solve this:
One isotope of a metallic element has mass # of 65 and 35 neutrons in nucleus. The cation derived from the isotope has 28 electrons. Write the symbol for this cation.
Would the symbol be Cu?
because Atomic # = protons = electrons
and Mass # = neutrons + protons
To solve this problem, use the information given to determine the atomic number and mass number of the element. From there, you can identify the element and write its symbol.
First, let's identify the atomic number (number of protons). Since the cation derived from the isotope has 28 electrons, this means the number of protons is also 28. Therefore, the atomic number is 28.
Next, let's determine the number of neutrons. The mass number of the isotope is given as 65, and the number of neutrons is 35. Since the mass number is the sum of protons and neutrons, we can calculate the number of protons by subtracting 35 from 65:
Mass number - Number of neutrons = Number of protons
65 - 35 = 30
So, the number of protons is 30.
Now that we know the atomic number (protons) and mass number (protons + neutrons), we can look up the element on the periodic table. In this case, the element with atomic number 28 is Nickel (Ni).
Finally, to write the symbol for the cation, we need to indicate the charge. Since it is not specified in the question, we'll assume the cation is positively charged. Given that the atomic number is 28 and the cation has lost 2 electrons (since it now has 28 electrons), we can determine the charge.
Since electrons are negatively charged, losing 2 electrons would result in a charge of +2. Therefore, the symbol for this cation would be Ni2+.
So, the symbol for the cation derived from the isotope with mass number 65 and 35 neutrons in the nucleus is Ni2+.