Question

1. how many protons, electrons, and neutrons are in each of the following isotopes?

a. uranium - 235
b. hydrogen - 3
c. silicon - 29

Explanation:

Step1: Recall atomic number concept

The atomic number ($Z$) of an element gives the number of protons. For a neutral atom, the number of electrons equals the number of protons. The mass number ($A$) is the sum of protons ($p$) and neutrons ($n$), i.e., $A = p + n$.

Step2: Find values for uranium - 235

• Protons and electrons: Uranium ($U$) has an atomic number $Z = 92$. So, protons ($p$) = 92 and electrons ($e$)=92 (since it's neutral).
• Neutrons: Mass number $A = 235$. Using $n=A - p$, we get $n = 235-92=143$.

Step3: Find values for hydrogen - 3

• Protons and electrons: Hydrogen ($H$) has an atomic number $Z = 1$. So, protons ($p$) = 1 and electrons ($e$)=1 (since it's neutral).
• Neutrons: Mass number $A = 3$. Using $n=A - p$, we get $n = 3 - 1=2$.

Step4: Find values for silicon - 29

• Protons and electrons: Silicon ($Si$) has an atomic number $Z = 14$. So, protons ($p$) = 14 and electrons ($e$)=14 (since it's neutral).
• Neutrons: Mass number $A = 29$. Using $n=A - p$, we get $n = 29-14 = 15$.

Answer:

a. Protons: 92, Electrons: 92, Neutrons: 143
b. Protons: 1, Electrons: 1, Neutrons: 2
c. Protons: 14, Electrons: 14, Neutrons: 15