Question

1. apply: turn off show isotope notation. set protons to 3 and neutrons to 4.write this isotope using isotope notation. hand write in this space or click here to select edit to use the drawing tool. check your answer in the gizmo. 3. observe: set the protons to 8 and the neutrons to 9. a. how is the isotope written at the top left of the gray box? b. what does the number next to the element name indicate?

Explanation:

Step1: Recall isotope notation

Isotope notation is $\ce{^{A}_{Z}X}$, where $Z$ is the atomic number (number of protons) and $A$ is the mass - number (sum of protons and neutrons), and $X$ is the chemical symbol of the element.

Step2: For the first case (3 protons and 4 neutrons)

The atomic number $Z = 3$, and the element with $Z = 3$ is lithium (Li). The mass - number $A=3 + 4=7$. So the isotope notation is $\ce{^{7}_{3}Li}$.

Step3: For 3A (8 protons and 9 neutrons)

The atomic number $Z = 8$, and the element is oxygen (O). The mass - number $A=8 + 9 = 17$. At the top - left of the gray box, it is written as $\ce{^{17}O}$.

Step4: For 3B

The number next to the element name indicates the mass - number of the isotope.

Answer:

1. $\ce{^{7}_{3}Li}$

3A. $\ce{^{17}O}$
3B. The mass - number of the isotope.