Struktur Molekul Dasar - Kimia Kelas XI

Summary

The script discusses the various molecular geometries that arise from different arrangements of atoms and bonds. It covers seven key shapes: linear, trigonal planar, trigonal pyramidal, square planar, tetrahedral, trigonal bipyramidal, and octahedral. Examples include beryllium chloride, carbon dioxide, boron trifluoride, ammonia, methane, phosphorus pentachloride, and sulfur hexafluoride. The bond angles between atoms are also explained, highlighting how different spatial arrangements lead to distinct molecular shapes, such as 180° for linear and 109.5° for tetrahedral molecules.

Takeaways

• 🧬 A material is always made up of various types of atoms, and their arrangement is limited by bond angles and particle properties.
• ⚛️ There are seven basic molecular shapes: linear, trigonal planar, trigonal pyramidal, square planar, tetrahedral, trigonal bipyramidal, and octahedral.
• ➡️ A molecule is linear when its atoms are arranged in a straight line, with bond angles of 180° (e.g., beryllium chloride and carbon dioxide).
• 🔺 Trigonal planar molecules consist of four atoms where all atoms lie in the same plane, forming a triangular arrangement (e.g., boron trichloride, boron trifluoride).
• 🏔️ Trigonal pyramidal molecules form a pyramid shape with a central atom at the top and others at the base, with NH3 (ammonia) being an example.
• 🔳 Square planar molecules consist of five atoms arranged in a square, with the central atom in the middle (e.g., xenon fluoride).
• ⬛ Tetrahedral molecules are structured around a central atom with four others forming a pyramid-like shape, such as methane (CH4) with a bond angle of 109.5°.
• 🔶 Trigonal bipyramidal molecules consist of six atoms with two pyramid shapes sharing a base, featuring two different bond angles: 120° and 90° (e.g., phosphorus pentachloride, PCl5).
• ⏹️ Octahedral molecules consist of seven atoms with bond angles of 90°, forming an octahedral shape, such as sulfur hexafluoride (SF6).
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Q & A

What is the composition of a material according to the script?

A material is always composed of several types of atoms. The arrangement of atoms is limited by bond angles and the properties of the constituent particles.

What are the seven molecular shapes mentioned in the script?

The seven molecular shapes mentioned are linear, trigonal planar, trigonal pyramidal, square planar, tetrahedral, trigonal bipyramidal, and octahedral.

What defines a linear molecule, and can you provide examples?

A molecule is considered linear when its constituent atoms are arranged in a straight line. Examples include beryllium chloride (BeCl2) and carbon dioxide (CO2), with bond angles of 180 degrees.

What are the characteristics of a trigonal planar molecule, and can you give examples?

A trigonal planar molecule consists of four atoms with three surrounding the central atom in a triangular shape, all on the same plane. Examples include boron trichloride (BCl3) and boron trifluoride (BF3).

How does a trigonal pyramidal molecule differ from a trigonal planar molecule?

A trigonal pyramidal molecule is not flat and consists of a central atom at the top of a pyramid with three atoms at the base, forming a three-dimensional structure. An example is ammonia (NH3).

What is a square planar molecule, and what is an example?

A square planar molecule consists of five atoms, with four surrounding the central atom in a square shape. An example is xenon tetrafluoride (XeF4), with bond angles of 90 degrees.

What is the bond angle in a tetrahedral molecule, and can you provide an example?

In a tetrahedral molecule, the bond angle is 109.5 degrees. An example of a tetrahedral molecule is methane (CH4).

What is the structure of a trigonal bipyramidal molecule, and can you provide an example?

A trigonal bipyramidal molecule consists of six atoms with a central atom surrounded by atoms in two pyramids that share the same base. An example is phosphorus pentachloride (PCl5). The bond angles are 120 degrees in the plane and 90 degrees between the planes.

What defines an octahedral molecule, and what is an example?

An octahedral molecule has a central atom surrounded by six other atoms in a geometric shape resembling two pyramids joined at their bases. An example is sulfur hexafluoride (SF6), with bond angles of 90 degrees.

What is the bond angle in a trigonal bipyramidal molecule between the axial and equatorial positions?

In a trigonal bipyramidal molecule, the bond angle between the atoms in the triangular plane is 120 degrees, while the bond angle between the equatorial and axial positions is 90 degrees.