What is an atom?

What is an atom?

• A. The largest unit of matter
• B. Smallest unit of matter
• C. A molecule made of two atoms
• D. A type of element

Answer: (B)

Atoms are the basic building blocks of matter in chemistry, defined as the smallest unit that still has the properties of an element. An atom features a dense nucleus made of protons and neutrons, with electrons orbiting around it in electron clouds. Most of the atom’s mass sits in the nucleus, while surrounding space is mostly empty. Atoms join with other atoms to form molecules, which are the substances we actually encounter. The other statements describe larger scales or different concepts (a molecule is made of multiple atoms, an element is defined by its number of protons, not by being an atom itself, and the term “largest unit” isn’t correct for this level). So the atom is best described as the smallest unit of matter that retains an element’s properties.

Atoms are the basic building blocks of matter in chemistry, defined as the smallest unit that still has the properties of an element. An atom features a dense nucleus made of protons and neutrons, with electrons orbiting around it in electron clouds. Most of the atom’s mass sits in the nucleus, while surrounding space is mostly empty. Atoms join with other atoms to form molecules, which are the substances we actually encounter. The other statements describe larger scales or different concepts (a molecule is made of multiple atoms, an element is defined by its number of protons, not by being an atom itself, and the term “largest unit” isn’t correct for this level). So the atom is best described as the smallest unit of matter that retains an element’s properties.