Question

directions: select all the correct answers. which of the following statements about atoms are true?
☐ atoms may be joined together in well - defined molecules.
☐ atoms may be arranged in repeating crystal patterns.
☐ all ordinary substances are made of atoms.
☐ all known substances are made of molecules.
☐ atoms are always joined directly to other atoms.

Explanation:

• For option A: In covalent compounds, atoms bond to form well - defined molecules (e.g., $\ce{H_2O}$ has 2 H and 1 O atom bonded in a molecule).
• For option B: Ionic compounds (e.g., $\ce{NaCl}$) have atoms (ions) arranged in repeating crystal lattices.
• For option C: All ordinary matter (substances) is composed of atoms, which are the basic building blocks.
• For option D: Not all substances are made of molecules. Ionic compounds are made of ions, and some substances are atomic (e.g., noble gases like He are single atoms).
• For option E: Atoms are not always joined directly to other atoms. Noble gas atoms exist as single atoms (not joined to others under normal conditions).

Answer:

A. Atoms may be joined together in well - defined molecules.
B. Atoms may be arranged in repeating crystal patterns.
C. All ordinary substances are made of atoms.