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Questions and Answers
What is the formal charge of an atom with 6 valence electrons, 4 nonbonding electrons, and 2 bonds?
What is the formal charge of an atom with 6 valence electrons, 4 nonbonding electrons, and 2 bonds?
For which molecule is it possible to have an expanded valence shell?
For which molecule is it possible to have an expanded valence shell?
Which molecule is known for having resonance forms?
Which molecule is known for having resonance forms?
What is the preferred characteristic of stable Lewis structures?
What is the preferred characteristic of stable Lewis structures?
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What is the formal charge of an atom with 6 valence electrons and 3 bonds?
What is the formal charge of an atom with 6 valence electrons and 3 bonds?
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Which of the following has only one possible Lewis structure?
Which of the following has only one possible Lewis structure?
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What is the main reason for the preference of certain Lewis structures over others?
What is the main reason for the preference of certain Lewis structures over others?
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Which molecule contains a third-period element that can exhibit an expanded octet?
Which molecule contains a third-period element that can exhibit an expanded octet?
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Calculate the total number of valence electrons in the molecule CH2O.
Calculate the total number of valence electrons in the molecule CH2O.
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What is the electron-dot structure for ICl3 based on the total valence electron count?
What is the electron-dot structure for ICl3 based on the total valence electron count?
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Which molecule's electron-dot structure illustrates resonance?
Which molecule's electron-dot structure illustrates resonance?
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When drawing the electron-dot structure for SF6, how many valence electrons are used?
When drawing the electron-dot structure for SF6, how many valence electrons are used?
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In the context of formal charge, which statement is correct?
In the context of formal charge, which statement is correct?
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What is the role of moving a lone pair in the resonance structure of O3?
What is the role of moving a lone pair in the resonance structure of O3?
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When drawing the electron-dot structure for H2O, how many total valence electrons are counted?
When drawing the electron-dot structure for H2O, how many total valence electrons are counted?
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What is the arrangement of Cl atoms in the electron-dot structure for ICl3?
What is the arrangement of Cl atoms in the electron-dot structure for ICl3?
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What is primarily responsible for the stability of atoms or ions?
What is primarily responsible for the stability of atoms or ions?
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Which type of bonding occurs between metals and non-metals?
Which type of bonding occurs between metals and non-metals?
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What is a key step in drawing Lewis structures for molecules?
What is a key step in drawing Lewis structures for molecules?
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What must be done when there are not enough electrons to complete the octet for all atoms?
What must be done when there are not enough electrons to complete the octet for all atoms?
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In which scenario would you place excess electrons in pairs on the central atom?
In which scenario would you place excess electrons in pairs on the central atom?
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How many total valence electrons are used to draw the structure of H2O?
How many total valence electrons are used to draw the structure of H2O?
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What is the primary characteristic of covalent bonding?
What is the primary characteristic of covalent bonding?
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What is a common step included in drawing the electron-dot structure of CCl4?
What is a common step included in drawing the electron-dot structure of CCl4?
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Study Notes
Lewis Theory of Bonding
- Atoms/ions are stable with a noble gas-like electron structure (octet).
- Electrons are most stable when paired.
- Atoms form chemical bonds to achieve a stable octet.
Ionic Bonding
- Electrostatic attraction between positive and negative ions.
- Example: Na + Cl → Na+ + Cl- → NaCl
Covalent Bonding
- Valence electrons are shared between atomic nuclei.
- Example: Cl + Cl → Cl2
Rules for Drawing Lewis Structures
- Arrange atoms around the central atom (often the first in the formula).
- Count valence electrons (add for negative ions, subtract for positive ions).
- Place bonding pairs between the central atom and surrounding atoms.
- Complete octets of surrounding atoms. Extra electrons go on the central atom as lone pairs.
- Check if the central atom has an octet; form double or triple bonds if necessary.
- Enclose polyatomic ions in square brackets.
Exceptions to the Octet Rule
- Insufficient electrons to complete octets: create multiple bonds.
- Excess electrons: place them on the central atom as lone pairs.
Electron-Dot Structures of Polyatomic Molecules
- Determine the total valence electrons for the molecule.
- Arrange atoms and place bonding pairs between atoms.
- Complete octets of atoms.
- Place remaining electrons as lone pairs on the central atom.
- Example (H2O): 2(1) + 6 = 8 valence electrons, arrangement is H-O-H then use the remaining 4 electrons as lone pairs on Oxygen.
Formal Charge
- An atom "owns" all its nonbonding electrons and half of its bonding electrons.
- The formal charge is the charge an atom would have if the bonding electrons were shared equally.
- Formal charge of atom = valence electrons − (unshared electrons + ½ bonding electrons)
Writing Lewis Structures for Octet-Rule Exceptions
- Some molecules can have more than 8 electrons around the central atom. Elements in the 3rd period or lower can expand their valence shell.
- Example: SCIF5, H3PO4 and BCl2F are given as example for this
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Description
Test your understanding of the Lewis Theory of bonding with this quiz. It covers ionic and covalent bonding, rules for drawing Lewis structures, and exceptions to the octet rule. Perfect for chemistry students looking to reinforce their knowledge!
