Question

Which of the following is not an element? (1) Diamond (2) Graphite (3) Silica (4) Ozone

Short answer

Silica is not an element.

Step-by-step solution

- Understanding Element

An element is a substance that cannot be broken down into simpler substances by chemical means. Each element is made up of atoms of a single type.

- Analyzing Each Option

First, determine if each option is made up of a single type of atom (an element) or multiple types (a compound).

- Checking Diamond

Diamond is a form of carbon. It is composed entirely of carbon atoms. Therefore, diamond is an element.

- Checking Graphite

Graphite is another form of carbon, composed entirely of carbon atoms. Therefore, graphite is also an element.

- Checking Silica

Silica is a compound made up of silicon and oxygen atoms (SiO2). Therefore, silica is not an element.

- Checking Ozone

Ozone is made up of three oxygen atoms (O3). Since it is composed only of oxygen atoms, ozone is an element.

- Conclusion

All options except silica are substances made up of a single type of element. Thus, silica is the answer.

Key concepts

elements

Elements are pure substances consisting of only one type of atom. They are the building blocks of matter and cannot be broken down into simpler substances through chemical reactions. The periodic table of elements organizes all known elements in a systematic way. Some examples of elements include oxygen (O), hydrogen (H), and carbon (C). Each element has unique properties such as atomic number, atomic mass, and reactivity. For example, gold (Au) is valued for its malleability and conductivity, while helium (He) is known for being lightweight and non-reactive.

Understanding elements is crucial as they form the foundation for studying chemistry and understanding the composition of matter.

compounds

Compounds consist of two or more different types of atoms chemically bonded together. They can be broken down into simpler substances (elements) through chemical means. The properties of a compound are usually distinct from those of the individual elements that compose it. For example, water (H2O) is a compound made up of hydrogen and oxygen atoms. Both gases, hydrogen is highly flammable, and oxygen supports combustion, yet water is a liquid that extinguishes fire.

Another example is salt (NaCl), composed of sodium and chlorine. While sodium is a reactive metal and chlorine is a toxic gas, their combination yields a stable compound essential for life.

carbon allotropes

Allotropes are different forms of the same element that have distinct physical properties. Carbon, for instance, has several allotropes: diamond, graphite, and graphene. Despite being made entirely of carbon atoms, each allotrope has a unique structure and properties.

Diamond is renowned for its hardness and is used in cutting tools and jewelry. Its atoms are arranged in a tetrahedral lattice, making it extremely strong.

Graphite, on the other hand, is soft and slippery due to its layered structure. It is used as a lubricant and in pencils.

Graphene is a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice. It has exceptional electrical and thermal conductivity and is stronger than steel.

chemical composition

Chemical composition refers to the types and amounts of atoms that make up a substance. It determines the properties and behavior of the substance. Knowing the chemical composition is essential in fields such as chemistry, biology, and material science. For instance, the chemical composition of water is H2O, indicating it has two hydrogen atoms for every oxygen atom.

In the context of the exercise, understanding the chemical composition helps differentiate between elements and compounds. For example, knowing that silica (SiO2) combines silicon and oxygen atoms reveals it is a compound, not an element.

Similarly, understanding that diamond and graphite consist solely of carbon atoms helps classify them as elements. Understanding chemical composition aids in predicting reactions, properties, and potential applications of different substances.