Question

part d: mixed practice (21 - 25)

1. an isotope of hydrogen with 2 neutrons. $_1^3h$
2. an isotope of uranium with 146 neutrons and 92 protons. $_{92}^{238}u$
3. a calcium ion with 20 protons, 20 neutrons, and a 2+ charge - write full nuclear symbol.
4. identify the element: 33 protons, 42 neutrons. write symbol with a and z.
5. write the symbol for bromine with 35 protons and 45 neutrons.

Explanation:

Step1: Recall nuclear - symbol notation

The nuclear symbol is written as $_{Z}^{A}X$, where $Z$ is the atomic number (number of protons), $A$ is the mass number (number of protons + neutrons), and $X$ is the chemical symbol of the element.

Step2: Solve for 21

For hydrogen, the symbol is $H$. Given 1 proton ($Z = 1$) and 2 neutrons, the mass number $A=1 + 2=3$. The symbol is $_{1}^{3}H$.

Step3: Solve for 22

For uranium, the symbol is $U$. Given 92 protons ($Z = 92$) and 146 neutrons, the mass number $A=92 + 146 = 238$. The symbol is $_{92}^{238}U$.

Step4: Solve for 23

For calcium, the symbol is $Ca$. Given 20 protons ($Z = 20$), 20 neutrons, and a $2+$ charge. The mass number $A=20 + 20=40$. The nuclear symbol is $_{20}^{40}Ca^{2 + }$.

Step5: Solve for 24

Using the periodic table, an element with 33 protons is arsenic ($As$). Given 33 protons ($Z = 33$) and 42 neutrons, the mass number $A=33+42 = 75$. The symbol is $_{33}^{75}As$.

Step6: Solve for 25

For bromine, the symbol is $Br$. Given 35 protons ($Z = 35$) and 45 neutrons, the mass number $A=35 + 45=80$. The symbol is $_{35}^{80}Br$.

Answer:

1. $_{1}^{3}H$
2. $_{92}^{238}U$
3. $_{20}^{40}Ca^{2 + }$
4. $_{33}^{75}As$
5. $_{35}^{80}Br$