Lecture 4 - Mole, Balancing Equations, Enthalpy definitions (1)

Mole Definition

The number of atoms in exactly 12.000 g of pure 12C.

Avogadro's Number

6.022 × 10^23 atoms, which indicates the number of particles in one mole.

Molar Mass of Iron

The mass of one mole of iron is 55.85 g.

Polyatomic Ion

A charged species composed of two or more atoms bonded together, such as sulfate (SO4 2-).

Chemical Reaction

A process of reorganization of reactant molecules to form product molecules, involving breaking and making chemical bonds.

Endothermic Reaction

A reaction that absorbs heat, resulting in a positive ΔH value.

Exothermic Reaction

A reaction that releases heat, resulting in a negative ΔH value.

Diatomic Elements

Elements that exist as molecules made up of two atoms, such as H2, N2, and O2.

Molecular Formula

A representation of a molecule that indicates the actual numbers and kinds of atoms in a compound.

Hydrogen Ion (H+)

A positively charged ion formed when a hydrogen atom loses its electron.

Thiocyanate Ion

A polyatomic ion with the formula SCN-.

Glucose Formula

The chemical formula for glucose is C6H12O6.

Mass Percent Composition

The percentage by mass of each element in a compound.

Conservation of Mass

The principle stating that mass is not lost or gained in a chemical reaction.

Isotope

Atoms of the same element that have different numbers of neutrons.

Sulfate Ion

A polyatomic ion with the formula SO4 2-.