Which one of the following atoms has the largest atomic size?SodiumPotassiumMagnesiumAluminium

The atomic size of an atom is determined by the number of energy levels that are occupied by electrons. The more energy levels there are, the larger the atomic size.

Here are the atomic numbers of the given elements:

• Sodium (Na) - 11
• Potassium (K) - 19
• Magnesium (Mg) - 12
• Aluminium (Al) - 13

The atomic number corresponds to the number of protons in an atom, and in a neutral atom, the number of protons equals the number of electrons. The number of energy levels that are occupied by electrons is determined by the distribution of these electrons in the various energy levels or shells.

The electron configuration of the given elements are:

• Sodium (Na) - 2,8,1
• Potassium (K) - 2,8,8,1
• Magnesium (Mg) - 2,8,2
• Aluminium (Al) - 2,8,3

From the electron configurations, we can see that potassium has the most energy levels (4 levels), therefore, potassium has the largest atomic size among the given elements.