AP Chem Unit 2

Electronegativity

The ability of an atom to attract electrons in a bond; increases across a period and decreases down a group.

Nonpolar Covalent Bond

A bond where electrons are shared equally between atoms with similar electronegativity.

Polar Covalent Bond

A bond formed by the unequal sharing of electrons between atoms with different electronegativities.

Ionic Bond

A bond created through the transfer of electrons from one atom to another, typically between metals and nonmetals.

Octet Rule

Atoms tend to bond in such a way that they each have eight electrons in their valence shell.

Lewis Structure

A diagram that shows the valence electrons of atoms within a molecule and how they bond with one another.

Formal Charge

A hypothetical charge on an atom within a molecule, calculated by assuming that electrons in bonds are shared equally.

Resonance

The phenomenon where a molecule or ion can be represented by two or more valid Lewis structures.

Lattice Energy

The energy required to form a crystal lattice from gaseous ions or the energy released when it forms.

Hybridization

The mixing of atomic orbitals to create new hybrid orbitals suitable for pairing electrons to form chemical bonds.

VSEPR Theory

Valence Shell Electron Pair Repulsion theory; predicts the shape of molecules based on electron domain repulsion.

Metallic Bond

A bond formed between metal atoms where electrons are shared in a 'sea' of delocalized electrons.

Isomers

Molecules that have the same chemical formula but different structural arrangements of atoms.

Dipole Moment

A measure of the polarity of a molecule, determined by the vector sum of individual bond dipoles.

Crystalline Solids

Solids whose constituents (atoms, ions, or molecules) are arranged in an ordered structure.

Alloys

A mixture of two or more metals, designed to enhance desirable properties.

Expanded Octet

A situation where an atom accommodates more than eight electrons in its valence shell.

Sea of Electrons

A model describing the delocalized electrons in metallic bonds that allow metals to conduct electricity.

Ductile

The ability of a metal to be drawn out into a thin wire.

Malleable

The ability of a metal to be hammered or pressed into shape without breaking.