Chemistry Unit 7 Study Guide

chemical bonds

Forces of attraction that hold two atoms together, formed by the attraction between the positive nucleus of one atom and the negative electrons of another atom.

ionic bond

Electrostatic attraction between positive and negative ions.

covalent bond

Sharing of electrons between atoms.

metallic bond

The attraction of a metallic cation for delocalized electrons.

octet rule

Atoms will combine to form compounds to achieve 8 electrons in their outer energy level.

cations

Positive ions formed by metals that have lost electrons.

anions

Negative ions formed by nonmetals that have gained electrons.

lattice energy

The energy required to separate 1 mol of ions in an ionic compound.

ionic crystal

The repeating pattern of particle packing in an ionic compound.

crystal lattice

The three-dimensional geometric arrangement of particles in an ionic compound.

electrolyte

An ion in an aqueous solution that conducts electricity.

exothermic reaction

A chemical reaction in which forming new bonds releases more energy than it took to break the old bonds.

endothermic reaction

A reaction in which forming new bonds releases less energy than it took to break the old bonds.

dissolution reaction

Occurs when an ionic compound is dissolved in water, forming an ionic solution.

binary compound

A compound consisting of one metal and one nonmetal.

roman numerals

Used to denote the charge of transition metals in ionic compounds.

polyatomic ion

An ion composed of multiple atoms, such as sulfate (SO4^2-).

alloy

A mixture of elements that has metallic properties.

substitutional alloy

An alloy formed when some atoms in the original metallic solids are replaced by other metals of similar atomic structure.

interstitial alloy

An alloy formed when small holes in a metallic crystal are filled with smaller atoms.

delocalized electrons

Electrons that are not held by any specific atom and can move easily between atoms in a metallic bond.