Final answer:
Cesium (Cs) likely has the biggest atoms based on its position near the bottom of the periodic table's alkali metals, following the trend of increasing atomic size down a group.
Step-by-step explanation:
The size of an atom is defined by its atomic radius, which generally increases as one moves down the groups in the periodic table and decreases across a period from left to right. The element in question with the biggest atoms is likely cesium (Cs), which is situated near the bottom of the group 1 alkali metals, suggesting it has a larger atomic radius than other elements comparatively located above it in the periodic table.
In comparing atomic sizes, the periodic table trends are indispensable. For halogens, for instance, the size increases from fluorine to iodine (F < Cl < Br < I), correlating with a decrease in electronegativity. When considering ions, adding electrons often results in increased atomic size due to increased electron-electron repulsion, whereas removing electrons (forming cations) results in a smaller atomic size as the effective nuclear charge on remaining electrons increases.