Question

use the periodic table to answer the question. write the atomic symbol (including the atomic number) for the isotope of neodymium with 90 neutrons. • write the answer in the form $_z^a x$ using the atomic symbol button in the toolbar, where $a$ is the mass number, $z$ is the atomic number, and $x$ is the chemical symbol for the unknown element.

Explanation:

Step1: Find atomic number of neodymium

From periodic table, atomic number of neodymium ($\text{Nd}$) is $Z = 60$.

Step2: Calculate mass number

Mass number $A$ is sum of protons and neutrons. Protons equal atomic number. Given 90 neutrons, $A=60 + 90=150$.

Step3: Write atomic symbol

Atomic symbol is written as $_{Z}^{A}\text{X}$, so for neodymium it is $_{60}^{150}\text{Nd}$.

Answer:

$_{60}^{150}\text{Nd}$