What is an element?

What is an element?

• A. A pure substance that cannot be broken down by normal chemical or physical means
• B. A substance made of more than one type of atom
• C. A substance that can be decomposed into simpler substances
• D. A compound formed by metals and nonmetals

Answer: (D)

An element is a pure substance that consists of only one kind of atom and cannot be broken down into simpler substances by ordinary chemical reactions. This is what sets elements apart from other substances: they are the basic building blocks made from a single type of atom. For example, oxygen is just O atoms and isn’t decomposed into other substances through standard chemical methods. The other descriptions describe substances that are not elements. A substance made of more than one type of atom is not an element, since elements are defined by a single kind of atom. A substance that can be decomposed into simpler substances is characteristic of a compound (and sometimes mixtures). A compound formed by metals and nonmetals is a specific example of a compound, not an element.

An element is a pure substance that consists of only one kind of atom and cannot be broken down into simpler substances by ordinary chemical reactions. This is what sets elements apart from other substances: they are the basic building blocks made from a single type of atom. For example, oxygen is just O atoms and isn’t decomposed into other substances through standard chemical methods.

The other descriptions describe substances that are not elements. A substance made of more than one type of atom is not an element, since elements are defined by a single kind of atom. A substance that can be decomposed into simpler substances is characteristic of a compound (and sometimes mixtures). A compound formed by metals and nonmetals is a specific example of a compound, not an element.