Question

Which of the following statements about atoms are true?

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

Answer 1

Answers:
1. All known substances are made of molecules. — False. Many solids (metals, ionic salts, covalent-network solids like diamond) are not made of discrete molecules.
2. Atoms may be arranged in repeating crystal patterns. — True. Crystalline solids have atoms/ions/molecules in a repeating lattice.
3. All ordinary substances are made of atoms. — True. Everyday matter (solids, liquids, gases) is composed of atoms (exceptions would be non-matter such as electromagnetic radiation).
4. Atoms are always joined directly to other atoms. — False. Some atoms exist unbonded (noble gases as monatomic gases); also bonding can be delocalized (metals).
5. Atoms may be joined together in well-defined molecules. — True. Many substances consist of discrete molecules with specific formulas (e.g., H2O, CO2).