Question

Which of the following statements about atoms are true?

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

Answer 1

1. All known substances are made of molecules. — False. Many substances (metals, ionic solids like NaCl, covalent networks like diamond, and glasses) are not made of discrete molecules; they are extended structures or lattices.

2. All ordinary substances are made of atoms. — True. Ordinary matter (solids, liquids, gases) is composed of atoms (or ions built from atoms); exceptions would be non‑material things like light or plasmas where atoms are ionized.

3. Atoms are always joined directly to other atoms. — False. Atoms can exist isolated (e.g., noble gas atoms in a gas) or as ions in a lattice; they need not be covalently bonded to another atom at all times.

4. Atoms may be arranged in repeating crystal patterns. — True. Crystalline solids consist of atoms or ions in a repeating lattice (e.g., metals, salts, diamond).

5. Atoms may be joined together in well-defined molecules. — True. Many substances are discrete molecules (H2O, O2, CH4, etc.) where atoms are joined in definite stoichiometric arrangements.