Question

Which of the following statements about atoms are true?

All ordinary substances are made of atoms.
Atoms may be joined together in well-defined molecules.
Atoms may be arranged in repeating crystal patterns.
Atoms are always joined directly to other atoms.
All known substances are made of molecules.

Answer 1

True: 1, 2, 3.
False: 4 and 5.

Brief reasons:
- 1: Ordinary matter (chemistry/Everyday substances) is made of atoms.
- 2: Atoms can join in well-defined molecules (e.g., H2O, CO2).
- 3: Atoms can form repeating crystal lattices (e.g., NaCl, diamond, metals).
- 4 is false because atoms can exist unbonded (monatomic noble gases, isolated atoms in a vacuum or plasma).
- 5 is false because many substances are not molecular (ionic crystals, metallic solids, network covalent solids, monatomic gases).