Which statement best describes an atom?

• A. The smallest unit of an element that retains the chemical properties of that element
• B. A region of space outside the nucleus where neutrons are most likely found
• C. A positively charged particle found in the nucleus of every element
• D. A substance made of two or more elements chemically bonded together

Answer: (A)

Verified step by step guidance

1. Understand the definition of an atom: An atom is the fundamental unit of matter that defines the chemical properties of an element.
2. Recall that atoms consist of a nucleus containing protons and neutrons, with electrons orbiting in regions of space called electron clouds.
3. Recognize that the smallest unit of an element that retains the chemical properties of that element is an atom itself, not subatomic particles or compounds.
4. Eliminate incorrect options: Neutrons are found in the nucleus, not outside; protons are positively charged particles in the nucleus but do not alone define an atom; substances made of two or more elements chemically bonded are compounds, not atoms.
5. Conclude that the best description of an atom is 'The smallest unit of an element that retains the chemical properties of that element.'