Answer
(a) $^{58}_{27}$Co
(b) $^{10}_{5}$B
(c) $^{23}_{12}$Mg
(d) $^{132}_{53}$I
(e) $^{47}_{20}$Ca
(f) $^{65}_{29}$Cu
Work Step by Step
(a) We know that Z is the atomic number, which is also the number of protons in an atom, so a Z = 27 indicates that this is an isotope of cobalt. The Z value is written as a subscript to the left of the element symbol. We also need the A value, which is the mass number. The mass number is the sum of the number of protons and neutrons in the atom. If the number of protons is given as 27 and the number of neutrons is given as 31, we can add these two values to get a mass number of 58. The atomic symbol of this isotope is $^{58}_{27}$Co.
(b) We know that the mass number is 10, in this case; this is the A value. If we are given that the element we are working with is boron, then we know that its atomic number is 5, which is the value for Z. Now we have both the A value and the Z value, we write the A value as a superscript to the left of the element symbol and the Z value as a subscript of the element symbol. Therefore, the atomic symbol for this isotope is $^{10}_{5}$B.
(c) We know that Z is the atomic number, so a Z = 12 indicates that this is an isotope of magnesium. The Z value is written as a subscript to the left of the element symbol. We also need the A value, which is the mass number. The mass number is the sum of the number of protons and neutrons in the atom. We are given the A value as 23. This will be written as a superscript to the left of the element symbol. The atomic symbol for this isotope is $^{23}_{12}$Mg.
(d) We know that the atomic number, or the Z value, of this isotope is 53, which is also the number of protons in its nucleus. A Z value of 53 means that this is an isotope of iodine. We are given the number of neutrons, which is 79. The A value is the number of protons added to the number of neutrons. So if we add 53 protons to 79 neutrons, we get an A value of 132. We write the A value as a superscript to the left of the element symbol and the Z value as a subscript also to the left of the element symbol. Therefore, the atomic symbol for this isotope is $^{132}_{53}$I.
(e) We know that Z is the atomic number, so a Z =20 indicates that this is an isotope of calcium. The Z value is written as a subscript to the left of the element symbol. We also need the A value, which is the mass number. The mass number is the sum of the number of protons and neutrons in the atom. If the number of protons is given by the Z number (20) and the number of neutrons is given as 27, we can add these two values to get a mass number of 47. Therefore, the atomic symbol of this isotope is $^{47}_{20}$Ca.
(f) We know that Z is the atomic number, which is also the number of protons in an atom. We are given the number of protons, which is 29, making this an isotope of copper, or Cu. The Z value is written as a subscript to the left of the element symbol. We also need the A value, which is the mass number. The mass number is the sum of the number of protons and neutrons in the atom. We are given the mass number already, which is 65. Therefore, the atomic symbol for this isotope is $^{65}_{29}$Co.
