Question

Most substances are composed of__________rather than elemental substances.

Short answer

Most substances are composed of non-elemental substances, such as compounds and mixtures, rather than elemental substances. This is because most substances found in nature and used in everyday life consist of a combination of different elements.

Step-by-step solution

Identify types of substances

There are two main types of substances: elemental substances and non-elemental substances (which include compounds, mixtures, and other forms of matter).

Determine the most common type of substances

Most substances found in nature and used in everyday life are not made up of just one element; instead, they are a combination of different elements, which form compounds or mixtures. Thus, most substances are composed of non-elemental substances rather than elemental substances.

Key concepts

Elemental Substances

Elemental substances are the simplest forms of chemical matter and consist of only one type of atom. They cannot be broken down into simpler substances by chemical means. Elements are listed on the periodic table and include well-known examples like hydrogen (H), oxygen (O), and gold (Au). Each element has unique properties that distinguish it from others.

For instance, oxygen is a gas that supports combustion, while gold is a solid that is famous for its malleability and conductivity. Understanding elemental substances is crucial in chemistry because they serve as the building blocks for more complex forms of matter, such as compounds and mixtures.

Non-Elemental Substances

Non-elemental substances differ from elemental substances in that they are composed of two or more elements chemically bonded together. This broader category includes compounds and mixtures, which are composed of elements in fixed ratios or varying compositions, respectively. Unlike elements, non-elemental substances can exhibit properties that are entirely different from those of the elements they comprise.

Water (H₂O), for example, is a compound that is liquid at room temperature and essential for life, but it is composed of hydrogen and oxygen, which are gases under the same conditions.

Compounds

Compounds are specific types of non-elemental substances where two or more elements are chemically combined in a fixed ratio. The resulting substance has properties that are distinct from the elements that form it. Chemical bonds, such as ionic or covalent bonds, are responsible for holding the atoms together within a compound.

Common table salt (sodium chloride, NaCl) is an ionic compound formed from the elements sodium and chlorine. When these elements react, they produce a white crystalline solid that is very different in taste and appearance from either of its constituent elements.

Mixtures

Mixtures are combinations of two or more substances where the components are not chemically bonded and can vary in proportion. The components of a mixture maintain their individual properties and can often be separated by physical means. Mixtures can be homogeneous, meaning the composition is uniform throughout, or heterogeneous, with distinctly different regions.

Examples of mixtures include air (a homogeneous mixture of different gases) and salad (a heterogeneous mixture of vegetables, fruits, nuts, etc.). An understanding of mixtures is important because most of the materials we encounter in daily life, from the air we breathe to the food we eat, are mixtures.