Question

2 which of the following is a key principle of modern atomic theory?
electrons occupy specific, predictable orbitals with distinct energy levels.
atoms are composed of three subatomic particles: protons, neutrons, and electrons.
atoms of different elements are identical to one another.
atoms are the smallest, indivisible particles of matter.
clear all

Explanation:

To determine the key principle of modern atomic theory, we analyze each option:

• "Electrons occupy specific, predictable orbitals with distinct energy levels" is a key principle of modern atomic theory (quantum mechanical model), as electrons are described as existing in orbitals with quantized energy.
• "Atoms are composed of three subatomic particles: protons, neutrons, and electrons" is a fact about atomic structure but not a defining principle of the theory's explanation of atomic behavior.
• "Atoms of different elements are identical to one another" is incorrect (atoms of different elements have different properties).
• "Atoms are the smallest, indivisible particles of matter" is incorrect (atoms are divisible into subatomic particles and can be changed in nuclear reactions).

Answer:

The option "Electrons occupy specific, predictable orbitals with distinct energy levels" (the first option in the list of choices presented).