Question

1. choose the best answer.

which statement is true about isotopes?
isotopes of an element have the same number of protons but a different number of neutrons.
isotopes of an element have a different number of protons and a different number of neutrons.
isotopes of an element have the same number of protons and the same number of neutrons.
isotopes of an element have a different number of protons but the same number of neutrons.

1. use the periodic table to write the correct answer.

what is the isotopic notation for the isotope krypton - 84?
84
36 kr
kr 84
36
kr 36
84
36
84 kr

Explanation:

• For question 7:
• Isotopes are defined as atoms of the same element. Since they are of the same element, the number of protons (which defines the element) is the same. The difference between isotopes lies in the number of neutrons.
• For question 8:
• In isotopic notation, the general form is \(_{Z}^{A}X\), where \(Z\) is the atomic number (number of protons) and \(A\) is the mass number (sum of protons and neutrons). For krypton (\(Kr\)), from the periodic table, the atomic number \(Z = 36\). For krypton - 84, the mass number \(A=84\). So the isotopic notation is \(_{36}^{84}Kr\).

Answer:

• 7) Isotopes of an element have the same number of protons but a different number of neutrons.
• 8) \(_{36}^{84}Kr\)