How does Lucretius describe atoms in De rerum natura?

In his didactic poem De rerum natura, Lucretius describes atoms as the fundamental, irreducible particles of matter that constitute the entire universe alongside an infinite void.1

According to his exposition, atoms possess the following characteristics:

• Physical Nature: They are impenetrably hard, changeless, and everlasting, representing the absolute limit of physical division.1
• Composition: Each atom is composed of inseparable minimal parts or units; while larger atoms contain more of these units, all atoms remain minute.1
• Properties: Atoms differ from one another only in terms of their shape, size, and weight.1
• Behavior: All things are viewed as systems of moving atoms separated by intervals of void. These systems cohere based on the shapes of their constituent atoms. Change in the physical world is explained entirely through the addition, subtraction, or rearrangement of these immutable particles.1
• The Swerve: Lucretius posits that atoms would move eternally downward in a straight line through infinite space if they did not occasionally "swerve" at a minimal degree. This indeterminate motion allows for the collision of atoms to form worlds and provides the basis for free will.1