Question

57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
la ce pr nd pm sm eu gd tb dy ho er tm yb lu
89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
ac th pa u np pu am cm bk cf es fm md no lr
carbon helium hydrogen iodine oxygen sodium
diatomic element monatomic element

Explanation:

Step1: Recall diatomic and monatomic elements

Diatomic elements are those that exist as molecules composed of two atoms (e.g., \(H_2\), \(O_2\), \(I_2\)). Monatomic elements exist as single atoms (e.g., noble gases like He, and some metals/non - metals like C, Na in their elemental state under normal conditions).

• Hydrogen (\(H_2\)): Diatomic.
• Iodine (\(I_2\)): Diatomic (exists as diatomic molecules in elemental form).
• Oxygen (\(O_2\)): Diatomic (elemental oxygen is diatomic).

• Helium (He): Noble gas, exists as single atoms (monatomic).
• Carbon (C): In elemental form (like graphite, diamond) exists as atoms covalently bonded in a network, but as a gas - phase atom or in terms of elemental particles, we consider it monatomic in the context of this classification (since it doesn't form diatomic molecules).
• Sodium (Na): Metal, exists as individual atoms in the gaseous state or as ions in solution, but in elemental form (solid metal) has a metallic lattice, but for this classification, it is monatomic.

Step2: Classify each element

• Diatomic Elements: Hydrogen, Iodine, Oxygen.
• Monatomic Elements: Helium, Carbon, Sodium.

Answer:

Diatomic Element: hydrogen, iodine, oxygen
Monatomic Element: helium, carbon, sodium