Question

Silicon has great affinity towards oxygen. So, silicon occurs in the nature mostly in the form of (1) silicates (2) silica (3) silicon (4) orthosilicic acid

Short answer

(1) silicates

Step-by-step solution

- Understand the Affinity

Silicon has a high affinity for oxygen, meaning it readily combines with oxygen.

- Identify Natural Forms of Silicon

Silicon is commonly found in nature as compounds rather than in its pure elemental form due to its reactivity.

- Common Silicon Compounds

The two common forms of silicon compounds are silicates (compounds of silicon, oxygen, and metals) and silica (SiO2).

- Evaluate the Answer Choices

Among the given options: (1) silicates and (2) silica are the major natural forms in which silicon occurs, while (3) pure silicon and (4) orthosilicic acid are less common.

- Determine the Best Answer

Since silicon has a great affinity for oxygen, the most prevalent forms are silicates (1) and silica (2). These are the forms in which silicon predominantly exists in nature.

- Conclude the Best Option

Considering all options, silicates (1) cover a broader range of natural occurrences of silicon compared to silica.

Key concepts

Silicon Affinity for Oxygen

Silicon (Si) is a chemical element with a notable characteristic: a high affinity for oxygen (O). This means that silicon readily reacts with oxygen to form strong chemical bonds. This tendency is due to the chemistry of silicon atoms, which can effectively share electrons with oxygen atoms, creating stable compounds. Because of this characteristic, silicon rarely exists in its pure form in nature. Instead, it is typically found combined with oxygen, forming various silicon-oxygen compounds. This in-depth interaction is the foundational reason behind the prevalence of silica and silicates in the Earth's crust.

Silicates

Silicates are compounds consisting of silicon and oxygen, often combined with other metals. They are integral to the composition of many minerals on Earth. Silicates can be categorized into several types based on their structural forms, such as:
* **Nesosilicates** - these consist of isolated silicon-oxygen tetrahedra.
* **Inosilicates** - these have chain-like structures, either single chains or double chains.
* **Phyllosilicates** - these form sheet-like structures which make up minerals like mica.
* **Tectosilicates** - these have a three-dimensional network of silicon and oxygen atoms.
This classification reflects the complex yet fascinating nature of silicate chemistry. Silicates are omnipresent in various geological settings, from the sand on beaches to the minerals in rocks, accounting for a major portion of the Earth's crust.

Silica

Silica, or silicon dioxide (SiO2), is another prevalent form of silicon. It is the second most common mineral in the Earth's crust. Silica commonly occurs in nature in various forms:
* **Quartz** - this is the most stable form of crystalline silica, known for its hardness and resistance to weathering.
* **Cristobalite and Tridymite** - these are high-temperature forms of silica, typically found in volcanic rocks.
* **Amorphous silica** - unlike its crystalline counterparts, this form lacks a defined structure and can be found in opals, for example.
Silica's unique properties make it important not only in geology but also in industrial applications such as glass making, construction materials, and electronics.