Suggest a plausible structure for the silicate anion in the mineral thortveitite, Sc₂Si₂O₇.

Verified step by step guidance

1. Identify the chemical formula of the silicate anion in thortveitite, which is Si_2O_7^6-.
2. Recognize that the silicate anion Si_2O_7^6- is a type of sorosilicate, where two SiO_4 tetrahedra share one oxygen atom.
3. Visualize the structure: each silicon atom is at the center of a tetrahedron, and the tetrahedra are linked by sharing one oxygen atom, forming a Si-O-Si bridge.
4. Count the total number of oxygen atoms: each SiO_4 tetrahedron has 4 oxygen atoms, but sharing one oxygen reduces the total to 7.
5. Consider the charge: each SiO_4 unit has a charge of 4-, and sharing one oxygen results in a total charge of 6- for the Si_2O_7 anion.

Key Concepts

Silicate Anions

Silicate anions are polyatomic ions composed of silicon and oxygen, typically represented as SiO4 tetrahedra. In silicates, these tetrahedra can link together in various configurations, forming chains, sheets, or three-dimensional frameworks. Understanding the arrangement of these tetrahedra is crucial for predicting the properties and structures of silicate minerals.

Thortveitite Structure

Thortveitite is a mineral that contains the silicate anion Si2O7, which consists of two SiO4 tetrahedra sharing one oxygen atom. This unique arrangement leads to a specific structural framework that influences the mineral's physical properties. Recognizing how these tetrahedra combine helps in visualizing the overall geometry of the mineral.

Coordination and Bonding

In thortveitite, the coordination of the Scandium (Sc) ions is essential for stabilizing the silicate structure. Scandium typically exhibits a coordination number of 6, meaning it is surrounded by six oxygen atoms. Understanding the bonding and coordination in minerals is vital for predicting their stability, reactivity, and overall crystal structure.