Chapter 3: Chemical Bonding Flashcards
What is ionic bonding?
Electrostatic attraction between positive and negative ions.
How are positive ions formed?
By losing one or more electrons.
How are negative ions formed?
By gaining one or more electrons.
Why do elements in Group 14 generally not form ions?
They have four valence electrons and no tendency to gain or lose electrons.
What is the structure of ionic compounds?
A lattice structure.
What is a key property of ionic compounds related to temperature?
High melting and boiling points.
In what state do ionic compounds conduct electricity?
Molten or dissolved in water
What is a covalent bond?
A bond formed by sharing valence electrons.
What determines bond polarity?
The difference in electronegativity between bonded atoms.
How does bond strength change with bond length?
Shorter bonds are stronger.
What is the octet rule?
Atoms tend to have eight electrons in their valence shell.
Which elements often form stable compounds with incomplete octets?
Beryllium (Be) and Boron (B).
What are resonance structures?
Multiple valid arrangements of electrons in a molecule.
What theory determines molecular shape?
VSEPR theory (Valence Shell Electron Pair Repulsion).
How does electron domain affect molecular geometry?
Electron domains repel and spread as far as possible.
What is a lone pair?
A pair of valence electrons not involved in bonding.
What is an expanded octet?
More than 8 electrons around a central atom.
Why can atoms have expanded octets?
d orbitals in valence shell with energy close to p orbitals are available. Electron from p promote to occupy d.
Which elements can have expanded octets?
Period 3 and below (e.g. Cl, S, F, etc.)
What are delocalized electrons?
Electrons free to move in a metallic lattice.
What increases the strength of metallic bonding?
Higher positive charge
What type of molecules experience London dispersion forces?
All molecules
What is dipole-dipole attraction?
Attraction between permanent dipoles in polar molecules.
What is hydrogen bonding?
A strong dipole-dipole attraction involving H and highly electronegative atoms (N, O, F,..)
Why do substances with hydrogen bonds have high boiling points?
Hydrogen bonding is the strongest intermolecular force.
What are giant covalent substances?
Substances with continuous covalent networks.
What is the electron geometry for 2 electron domains?
Linear.
What is the electron geometry for 3 electron domains?
Trigonal planar.
What is the electron geometry for 4 electron domains?
Tetrahedral.
Why is H2O bent but BeH2 linear?
Lone pairs on oxygen in H2O cause repulsion.
Why is NH3’s bond angle smaller than CH4’s?
Lone pairs on nitrogen cause greater repulsion.
What is the molecular geometry of CF4?
Tetrahedral.
What is the molecular geometry of BF3?
Trigonal planar.
Why do ionic compounds dissolve in polar solvents?
Attraction between ions and solvent molecules.
What is the primary feature of a metallic lattice?
A regular arrangement of metal cations surrounded by a sea of delocalized electrons.
Which molecules have higher boiling points: polar or nonpolar?
Polar molecules.
What causes the bending shape in molecules like water?
Lone pairs causing greater electron repulsion.
What defines molecular polarity?
Shape and arrangement of polar bonds.
Why do metals conduct electricity?
Free-moving delocalized electrons.
What is a key feature of covalent bonds in terms of shared electrons?
Single bonds share 2 electrons; double share 4