The chemical formula CCl4 represents a well-known covalent compound composed of one carbon atom and four chlorine atoms. Understanding its name requires knowledge of chemical nomenclature rules, especially those governing covalent (molecular) compounds.
In this article, we will explore the systematic name of CCl4, its structure, properties, and related compounds.
Understanding Chemical Formulas and Nomenclature
Chemical formulas provide concise information about the types and numbers of atoms in a compound. For molecular compounds, the formula indicates the exact number of each atom present, unlike ionic compounds where the formula represents the simplest ratio of ions.
When naming covalent compounds like CCl4, prefixes are used to denote the number of atoms of each element. These prefixes include mono-, di-, tri-, tetra-, and so forth.
The second element’s name typically ends with the suffix “-ide”.
Example: CO2 is called carbon dioxide, where “di-” denotes two oxygen atoms.
The Name of CCl4
The compound CCl4 is named carbon tetrachloride. This name follows the standard nomenclature for covalent compounds:
- The first element (carbon) is named as is.
- The second element (chlorine) is modified to end with -ide becoming chloride.
- The prefix tetra- indicates that four chlorine atoms are present.
Since there is only one carbon atom, the prefix mono- is omitted for the first element.
Breaking Down the Name: Carbon Tetrachloride
Carbon is a nonmetal element with atomic number 6. It forms the central atom in this molecule.
Tetrachloride indicates the presence of four chlorine atoms bonded to the carbon. The prefix tetra- means four, derived from Greek, and chloride signifies chlorine atoms in an anionic or bonded form.
Thus, the complete name carbon tetrachloride clearly describes the molecule’s composition in a standardized manner.
Table: Prefixes for Number of Atoms in Covalent Compounds
| Number of Atoms | Prefix |
|---|---|
| 1 | Mono- |
| 2 | Di- |
| 3 | Tri- |
| 4 | Tetra- |
| 5 | Penta- |
| 6 | Hexa- |
Structural Details of Carbon Tetrachloride
Carbon tetrachloride is a tetrahedral molecule. The carbon atom is located at the center with four chlorine atoms positioned symmetrically around it.
This arrangement allows for equal repulsion between electron pairs, resulting in a bond angle of approximately 109.5°.
The bonds between carbon and chlorine are covalent, meaning the atoms share electrons to achieve a stable electron configuration.
Note: The symmetrical shape of CCl4 makes it nonpolar despite the polarity of individual C-Cl bonds.
Visual Representation of CCl4
| Element | Number of Atoms | Electronegativity | Role |
|---|---|---|---|
| Carbon (C) | 1 | 2.55 | Central atom |
| Chlorine (Cl) | 4 | 3.16 | Surrounding atoms |
Physical and Chemical Properties of Carbon Tetrachloride
Carbon tetrachloride is a colorless, volatile liquid with a sweet odor. It is dense and has been used historically as a cleaning agent, refrigerant, and fire extinguisher component.
Despite its usefulness, CCl4 is toxic and harmful to the liver and kidneys. It has been largely phased out of consumer products due to its health hazards and environmental impact, including its role in ozone layer depletion.
Key Properties of Carbon Tetrachloride
| Property | Value |
|---|---|
| Molecular Weight | 153.82 g/mol |
| Melting Point | -23.0 °C |
| Boiling Point | 76.72 °C |
| Density | 1.59 g/cm3 (at 20 °C) |
| Solubility in Water | 0.08 g/100 mL (very low) |
Applications of Carbon Tetrachloride
Historically, carbon tetrachloride was widely used as a solvent for oils, fats, lacquers, and varnishes. Its nonflammable nature made it valuable in fire extinguishers.
In organic chemistry, it is also used as a solvent in various reactions and as a precursor in the synthesis of refrigerants like chlorofluorocarbons (CFCs).
However, due to its toxicity and environmental hazards, many of these uses have been restricted or replaced by safer alternatives.
Environmental and Health Concerns
Carbon tetrachloride is a potent hepatotoxin and nephrotoxin, meaning it damages the liver and kidneys even at relatively low exposures. It can be absorbed via inhalation, ingestion, or skin contact.
Environmentally, CCl4 is a significant contributor to ozone layer depletion. It has a long atmospheric lifetime and participates in complex photochemical reactions that break down ozone molecules.
Important: The use of carbon tetrachloride is strictly regulated under international agreements such as the Montreal Protocol.
Comparison with Similar Covalent Compounds
Carbon tetrachloride belongs to a class of tetrahalomethanes, where four halogen atoms are bonded to a central carbon atom. Variations include:
| Compound | Formula | Name | Halogen(s) |
|---|---|---|---|
| CF4 | CF4 | Carbon tetrafluoride | Fluorine |
| CCl4 | CCl4 | Carbon tetrachloride | Chlorine |
| CBr4 | CBr4 | Carbon tetrabromide | Bromine |
| CI4 | CI4 | Carbon tetraiodide | Iodine |
All these compounds share tetrahedral geometry and covalent bonding, but differ significantly in physical properties and reactivity due to the nature of the halogen atoms.
Summary
The covalent compound with the formula CCl4 is called carbon tetrachloride. This name reflects the molecule’s composition: one carbon atom bonded to four chlorine atoms.
Carbon tetrachloride has a tetrahedral molecular geometry and is a dense, nonpolar solvent with historical industrial importance. Despite its usefulness, it poses serious health and environmental risks, leading to reduced usage and regulatory controls.
Understanding the naming conventions and properties of CCl4 provides insight into molecular chemistry, nomenclature rules, and the balance between chemical utility and safety.
