What is a substance composed of only one type of atom and cannot be broken down by chemical reactions?

What is a substance composed of only one type of atom and cannot be broken down by chemical reactions?

• A. Mixtures
• B. Ionic compound
• C. Elements
• D. Compound

Answer: (C)

Elements are substances that contain only one type of atom. Because they’re made of a single kind of atom, chemical reactions can rearrange the atoms but cannot break the substance down into simpler substances—the identity of the atom remains the same. To actually split an element into something simpler you’d need nuclear changes, not ordinary chemical reactions. This is what sets elements apart from mixtures and compounds: mixtures are just blends of different substances that can be separated by physical methods, and compounds are formed from two or more elements joined together in fixed ratios and can be decomposed by chemical reactions into their elements or simpler compounds. For example, oxygen gas is an element, while water is a compound, and air is a mixture.

Elements are substances that contain only one type of atom. Because they’re made of a single kind of atom, chemical reactions can rearrange the atoms but cannot break the substance down into simpler substances—the identity of the atom remains the same. To actually split an element into something simpler you’d need nuclear changes, not ordinary chemical reactions. This is what sets elements apart from mixtures and compounds: mixtures are just blends of different substances that can be separated by physical methods, and compounds are formed from two or more elements joined together in fixed ratios and can be decomposed by chemical reactions into their elements or simpler compounds. For example, oxygen gas is an element, while water is a compound, and air is a mixture.