Final answer:
The statement that an element is made of only one kind of atom is true. Elements are pure substances that cannot be chemically broken down and their identity is determined by the atomic number, which is the number of protons in their atoms.
Step-by-step explanation:
An element is made out of only one kind of atom. This statement is true. An element is a pure substance made up of one type of atom and cannot be broken down into simpler substances through chemical means. The identity of an element is defined by its atomic number, which is determined by the number of protons found in the nucleus of its atoms.
For example, all atoms of hydrogen have exactly one proton, giving hydrogen an atomic number of 1, while all atoms of iron have 26 protons, giving iron an atomic number of 26. It is the unique number of protons that distinguishes one element from another, as seen on the Periodic Table of the Elements.
Atoms themselves are extremely small units that comprise the elements. For instance, it takes about fifty million hydrogen atoms to make a line that is 1 cm long. Despite their minuscule size, it is these atoms that are the fundamental building blocks of all matter, including everything from microscopic organisms to galaxies.
Each element has unique physical and chemical properties, and while there are 118 recognized elements, only a few are commonly found in living organisms on Earth. The complexity and diversity of matter we observe is due to the various ways in which different elements can combine to form compounds.