Determining Subatomic Particles
in an Aluminum Ion

Understanding Atomic Notation

To solve for the number of subatomic particles in any given ion, we first need to understand the notation used in chemistry, represented as $^A_Z X^q$:

• $X$: The chemical symbol (e.g., Al for Aluminum).
• $Z$ (Atomic Number): The subscript at the bottom left. This represents the number of protons in the nucleus and defines the element.
• $A$ (Mass Number): The superscript at the top left. This is the sum of protons and neutrons in the nucleus ($A = \text{protons} + \text{neutrons}$).
• $q$ (Charge): The superscript on the right. This indicates if electrons have been lost (positive charge) or gained (negative charge).

In the symbol $^{27}_{13} \text{Al}^{3+}$:

• $A = 27$
• $Z = 13$
• Charge = $+3$

Step-by-Step Calculation

1. Calculating Neutrons

Neutrons are found by subtracting the atomic number from the mass number:

$\text{Neutrons} = A - Z$ $\text{Neutrons} = 27 - 13 = 14$

There are 14 neutrons in this aluminum isotope.

2. Calculating Electrons

For a neutral atom, the number of electrons equals the number of protons ($Z$). However, an ion has a charge.

• A positive charge ($3+$) means the atom has lost 3 electrons.
• Protons = 13
• Electrons = (Protons) - (Charge)
• Electrons = $13 - 3 = 10$

There are 10 electrons in the $\text{Al}^{3+}$ ion.

Summary

• Protons: 13 (determined by the atomic number).
• Neutrons: 14 ($27 - 13 = 14$).
• Electrons: 10 (neutral 13 electrons minus 3 lost to create a $+3$ charge).

By following these steps, you can determine the composition of any ion provided in this standard format!