Topic 4 Bonding And Lewis Structure Flashcards
What are the three main types of chemical bonds?
Ionic, covalent, and metallic
What is the octet rule?
Atoms tend to gain, lose, or share electrons to achieve a full outer shell of 8 electrons, resembling the electron configuration of noble gases
What is the main difference between ionic and covalent bonds?
Ionic bonds result from the transfer of electrons, while covalent bonds result from the sharing of electrons.
Define electronegativity.
The ability of an atom to attract a shared pair of electrons in a covalent bond.
What is a Lewis structure?
A representation of a molecule that shows all valence electrons, including bonding and non-bonding (lone) pairs.
What kind of bond forms between two nonmetals?
Covalent bond.
What kind of bond forms between a metal and a nonmetal?
Ionic bond.
Why are metallic bonds conductive?
Because their delocalized electrons can move freely throughout the metallic lattice.
Why do ionic compounds have high melting points?
Due to the strong electrostatic forces of attraction between oppositely charged ions.
How many electrons are shared in a double covalent bond?
Four electrons.
Draw the Lewis structure for water (H₂O).
Oxygen has 6 valence electrons, forms two single bonds with two hydrogen atoms, and has two lone pairs.
Draw the Lewis structure for methane (CH₄).
Carbon forms four single bonds with four hydrogen atoms and has no lone pairs.
What is the formula of the ionic compound formed between magnesium and oxygen?
MgO
Predict the type of bonding in CO₂ and explain why.
Covalent bonding, because it is formed between two nonmetals (carbon and oxygen).
Which has a smaller radius: Cl or Cl⁻? Why?
Cl⁻ is larger because it gains an electron, increasing electron-electron repulsion in the outer shell.
How do you determine the central atom in a Lewis structure?
The central atom is usually the least electronegative element (except hydrogen).
Why do lone pairs affect molecular geometry?
Lone pairs repel more strongly than bonding pairs, distorting bond angles.
Describe the bonding in a diatomic nitrogen molecule (N₂).
N₂ has a triple bond, sharing six electrons between two nitrogen atoms to satisfy the octet rule.
Which element is most likely to violate the octet rule, and why?
Phosphorus or sulfur, because they can expand their octet by using d-orbitals.
Explain why ionic bonds are stronger than covalent bonds in some cases.
Ionic bonds involve the electrostatic attraction between ions, which is typically stronger than the overlap of electron orbitals in covalent bonds.
Draw the Lewis structure for CO₂.
- Carbon is the central atom with 4 valence electrons.
- Each oxygen atom (6 valence electrons) forms a double bond with carbon to complete the octet for all three atoms.
- Structure: O = C = O
What type of bond forms in AlCl₃? Explain your reasoning.
- AlCl₃ primarily exhibits covalent bonding because aluminum shares its three valence electrons with chlorine.
- However, due to the polar nature of Al-Cl bonds (difference in electronegativity), the bonding has partial ionic character.
Draw the Lewis structure for ammonia (NH₃), and predict its molecular shape
Lewis structure:
Nitrogen (5 valence electrons) forms three single bonds with three hydrogen atoms. Nitrogen also has one lone pair.
Molecular Shape:
Trigonal pyramidal due to the lone pair causing a distortion.
Why does NaCl dissolve in water? Explain using bonding principles
- NaCl dissolves because water is polar. The partially negative oxygen in water attracts the Na⁺ ions, and the partially positive hydrogens attract the Cl⁻ ions. This breaks the ionic bonds in NaCl and forms ion-dipole interactions.
