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Questions and Answers
Lewis structures show the arrangement of valence electrons in a molecule using ______ to represent bonding pairs and lone pairs.
Lewis structures show the arrangement of valence electrons in a molecule using ______ to represent bonding pairs and lone pairs.
dots or lines
Some molecules can be represented by two or more Lewis structures that are equally valid, known as ______ structures.
Some molecules can be represented by two or more Lewis structures that are equally valid, known as ______ structures.
resonance
In a special type of covalent bond called a ______ covalent bond, one atom provides both electrons in the shared pair.
In a special type of covalent bond called a ______ covalent bond, one atom provides both electrons in the shared pair.
coordinate
Ball-and-stick models represent atoms as spheres and ______ as sticks, allowing visualization of molecular shape.
Ball-and-stick models represent atoms as spheres and ______ as sticks, allowing visualization of molecular shape.
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Molecules containing elements in the third row and beyond can exceed the octet rule by using ______ orbitals to accommodate more than eight valence electrons.
Molecules containing elements in the third row and beyond can exceed the octet rule by using ______ orbitals to accommodate more than eight valence electrons.
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Covalent bonding involves the sharing of ______ pairs between atoms.
Covalent bonding involves the sharing of ______ pairs between atoms.
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Covalent bonds typically form between ______ atoms.
Covalent bonds typically form between ______ atoms.
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In a polar covalent bond, there is an ______ sharing of electron pairs.
In a polar covalent bond, there is an ______ sharing of electron pairs.
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The distance between two nuclei involved in a bond is called ______ length.
The distance between two nuclei involved in a bond is called ______ length.
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Compounds that do not readily conduct electricity are generally described as having ______ conductivity.
Compounds that do not readily conduct electricity are generally described as having ______ conductivity.
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The number of shared electron pairs between two atoms is known as ______ order.
The number of shared electron pairs between two atoms is known as ______ order.
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Molecular structures of covalent compounds are determined by ______ electrons.
Molecular structures of covalent compounds are determined by ______ electrons.
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Covalent compounds often have ______ melting and boiling points compared to ionic compounds.
Covalent compounds often have ______ melting and boiling points compared to ionic compounds.
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Study Notes
Overview of Covalent Bonding
- Covalent bonding involves the sharing of electron pairs between atoms.
- This sharing allows each atom to achieve a more stable electron configuration, often resembling that of a noble gas.
- The shared electron pairs are called bonding pairs.
- Covalent bonds typically form between nonmetal atoms.
Characteristics of Covalent Bonds
- Bonds are formed by the electrostatic attraction between the positively charged nuclei and the shared negatively charged electrons.
- The shared electron pairs are attracted to both positively charged nuclei.
- This attraction holds the atoms together.
- Covalent bonds vary in strength depending on the atoms involved and the number of shared electron pairs.
Types of Covalent Bonds
- Nonpolar covalent bonds: Equal sharing of electron pairs between identical or very similar atoms. Example: H₂ (hydrogen gas).
- Polar covalent bonds: Unequal sharing of electron pairs between atoms with different electronegativities. The atom with higher electronegativity attracts the shared electrons more strongly, leading to a partial negative charge on that atom and a partial positive charge on the other. Example: H₂O (water). The oxygen atom is more electronegative than the hydrogen atoms.
Factors Influencing Bond Strength
- Bond length: The distance between the two nuclei involved in the bond. Shorter bonds generally correspond to stronger bonds, although this isn't a strict rule.
- Bond order: The number of shared electron pairs between two atoms (single, double, or triple bonds). Triple bonds are stronger and shorter than single bonds.
- Electronegativity difference: The greater the electronegativity difference between the atoms, the more polar the bond and the stronger the attraction.
Properties of Covalent Compounds
- Low melting and boiling points: Generally weaker intermolecular forces compared to ionic compounds.
- Poor conductivity: Do not readily conduct electricity as solids or in solution, because they lack free electrons or ions.
- Solubility: Solubility varies. Some covalent compounds are soluble in nonpolar solvents (like oils) while others are soluble in polar solvents (like water). This depends on the polarity of the compound.
- Molecular structures: Covalent compounds often form molecules with specific shapes and arrangements of atoms, dictated by the valence electrons and bonding patterns.
Representing Covalent Bonds
- Lewis structures: Show the arrangement of valence electrons in a molecule using dots or lines to represent bonding pairs and lone pairs.
- Structural formulas: Show the arrangement of atoms and bonds using lines to represent pairs of shared electrons.
- Ball-and-stick models: Represent atoms as spheres and bonds as sticks, allowing visualization of molecular shape.
Exceptions to the Octet Rule
- Some molecules, particularly those containing elements in the third row and beyond (e.g., phosphorus, sulfur), can exceed the octet rule by using d orbitals to accommodate more than eight valence electrons.
- This happens because the availability of additional orbitals allows for expansion of the valence shell.
Resonance Structures
- Some molecules can be represented by two or more Lewis structures that are equally valid.
- These structures are called resonance structures, and the true structure is a hybrid of all the contributing structures.
- They are useful to represent delocalization of electrons.
Coordinate Covalent Bonds
- A special type of covalent bond where one atom provides both electrons in the shared pair. This is often seen in complex compounds and acids like those containing ammonium ions.
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Description
This quiz covers the fundamentals of covalent bonding, including the sharing of electron pairs and the characteristics that define these bonds. Additionally, you will learn about the different types of covalent bonds, such as nonpolar and polar covalent bonds, along with examples for better understanding.
