Almost any sample of matter—a rock, a piece of wood, a butterfly wing—is made up of smaller bits. Your phone, for example, is made up of several components, including the display with its light-emitting diodes, the battery, the camera, and the silicon processors that power it.

Memory and computing capabilities. In addition, special microscopes that image surfaces are available.

At the atomic level, you can see even smaller parts—the silicon atoms that make up the structure. Atoms are the ultimate particles that comprise everything.

Scientists are far from the first to question what things are composed of.

The philosophers of ancient Greece did as well, and most thought that everything was made of one or, at most, a few elemental substances (elements), the qualities of which gave rise to the properties of everything else.

Democritus, the founder of atomism (c. 460–370 bc), used a different method. The logic went as follows: if you cut a piece of, say, aluminum foil smaller, and smaller, you must ultimately arrive at a particle of aluminum so tiny that it can no longer be detected, no longer be clipped. As a result, the matter is ultimately made up of indivisible particles. There is nothing but empty space between them.

He referred to the particles as atoms (Greek atomos, meaning "uncuttable") and declared, "According to the convention, there is a sweet and a bitter, a hot and a cold, and... there is order." In reality, there are only atoms to avoid.”

However, Aristotle, one of the finest and most important thinkers of Western culture, stated that “nothing” could exist, and the notion of atoms was repressed for the next 2000 years. Finally, in the 17th century, the English scientist Robert Boyle claimed that an element is defined as “simple Bodies, not created of any other Bodies, of which all mixed Bodies are compounded, and into which they are finally resolved,” a description that is very similar to our concept of an atom.

An element is the most basic kind of substance, possessing distinct physical and chemical characteristics.

Elements have the following characteristics: An element is made up of only one type of atom, which is the smallest unit of an element. Because it keeps its chemical makeup, it cannot be broken down into a simpler form.

Any physical or chemical approach can be used to classify a sort of substance. Each element is distinct because the characteristics of its atoms are distinct. a component has a name, for example, silicon, oxygen, or copper.

A silicon sample includes just a sample of silicon has just silicon atoms, whereas a sample of copper includes only copper atoms.

Color, density, and combustibility are examples of macroscopic characteristics of silicon.

Based on its composition, matter can be classified into three types—elements, compounds, and mixtures.

Elements and compounds are called substances, matter with a fixed composition; mixtures are not substances because they have a variable composition.

Compounds. A compound is made up of two or more distinct elements that are chemically linked together. That is, the components in a compound have not simply been thrown together; their atoms have bonded in a chemical process.

There are many chemicals, Molecules make up substances such as ammonia, water, and carbon dioxide. However, there are many others. Sodium chloride and silicon dioxide, for example, do not.

All chemicals share three characteristics: The elements can be found in fixed portions by mass (have a fixed mass ratio). This is the case because each unit of the molecule is made up of a set number of atoms.

Consider the following ammonia sample. It contains 14 parts of nitrogen by weight. Ammonia gas is 14 parts N by mass and 3 parts H by mass. 1 N atom has 14 times the mass of 1 H atom. Each ammonia molecule consists of 1 N atom and 3 H atoms.

The qualities of a compound differ from the properties of its constituent components. Table 2.1 provides an eye-catching example: The soft, silvery sodium metal and the yellow-green, deadly chlorine gas they create are quite different from the white, crystalline substance they form.

• Law of mass conservation: the total mass of substances does not change during a chemical reaction.

Sodium chloride, often known as table salt. Unlike an element, a compound may be broken down into simpler substances—By a chemical transformation, component elements are transformed.

As an example, consider an electric current. Molten sodium chloride is broken down into metallic sodium and chlorine gas.

A mixture is made up of two or more things (elements and/or compounds) that are physically mixed together rather than chemically combined.

Mixtures differ from compounds in the following ways: The components of a mixture might vary in bulk. a combination of the compounds such as sodium chloride and water, for example, can include a wide range of constituents by weight of salt in relation to water.

Many of the qualities of its constituents are retained by a blend. For example, saltwater is colorless like water and tastes salty like sodium chloride.

Because a mixture comprises the individual units of its component elements and/or compounds on the atomic scale, the component characteristics are preserved. Unlike compounds, mixtures may be physically separated into their constituents.

Chemical modifications are not required. For instance, the water in saltwater can be removed by boiling, a physical process that results in the formation of solid sodium chloride.