The key difference between molecule and lattice is that a molecule contains atoms bonded to each other whereas a lattice contains atoms, molecules or ions bonded to each other.
Atoms join together to form various chemical substances. According to their arrangement, their properties change. The simplest unit that can form when atoms bind with each other is a molecule. If a very large number of atoms, ions or molecules combine with each other, then the result is a lattice. A lattice has a highly ordered structure and a very high molar mass.
CONTENTS
1. Overview and Key Difference
2. What is a Molecule
3. What is a Lattice
4. Side by Side Comparison – Molecule vs Lattice in Tabular Form
5. Summary
What is a Molecule?
Molecules are consisting of chemically bound two or more atoms of the same element (e.g., O2, N2) or different elements (H2O, NH3). Molecules don’t have charge, and the atoms bind with each other via covalent bonds. Moreover, they can be very large (haemoglobin) or very small (H2), depending on the number of atoms that connect with each other.
Figure 01: A Water Molecule
The molecular formula of a molecule shows the type and number of atoms in a molecule. The empirical formula gives the simplest integer ratio of atoms present in a molecule. For example, C6H12O6 is the molecular formula of glucose, and CH2O is the empirical formula. Molecular mass is the mass that we calculate considering the total number of atoms in the molecular formula. Furthermore, each molecule has its own geometry. Moreover, the atoms in a molecule arrange in a most stable manner with a specific bond angle and bond lengths to minimize the repulsions and strain forces.
What is a Lattice?
Lattice is a large network of atoms which has an ordered structure. In chemistry, we can see different types of ionic and covalent lattices. We can define a lattice as a solid that has a three- dimensional ordered arrangement of basic units. The basic unit can be an atom, molecule or an ion. Thus, lattices are crystalline structures with these repeated basic units.
Furthermore, if this network contains ions joined with ionic bonds, we call them as ionic crystals. For example, sodium chloride is an ionic lattice. Sodium is a group 1 metal, thus forms a +1 charged cation as its most stable cation. Chlorine is a nonmetal and has the ability to form a -1 charged anion. In the lattice, six chloride ions surround each sodium ion and vice versa. Due to all the electrostatic attractions between ions, the lattice structure is highly stable. The number of ions present in the lattice varies with the size of it. Lattice energy or enthalpy of the lattice is the measure of the strength of the ionic bonds in the lattice. Normally lattice enthalpy is exothermic.
Figure 02: Sodium Chloride Lattice Structure
Diamond and quartz are two examples of three-dimensional covalent lattices. Diamond is consisting of only carbon atoms, and each carbon atom covalently binds to four other carbon atoms to form the lattice structure. So each carbon atom has the tetrahedral arrangement. Diamond has high stability due to this structure. (Diamond is one of the strongest minerals on Earth.) Quartz or silicon dioxide also has covalent bonds, but these bonds exist between silicon and oxygen atoms (lattice of different atoms). Both of these covalent lattices have a very high melting point, and they cannot conduct electricity.
What is the Difference Between Molecule and Lattice?
A molecule forms when two or more atoms bind with each other either via covalent chemical bonds or ionic bonds. On the other hand, a lattice forms when a large number of atoms, molecules or ions bond with each other to forms a regular network structure. Hence, the key difference between molecule and lattice is that molecules contain atoms bonded to each other whereas lattices contain atoms, molecules or ions bonded to each other.
As another important difference between molecule and lattice, we can say that molecule can occur as solids, liquids or gases whereas lattices occur only as solid substances. Moreover, the mass of a molecule is very low compared to the mass of a lattice because the number of atoms in a lattice is comparatively very high.
More differences are shown below in the infographic of difference between molecule and lattice.
Summary – Molecule vs Lattice
Molecules and lattices are two important chemical terms in chemistry. They are different from each other; thus we cannot use them interchangeably. The key difference between molecule and lattice is that molecules contain atoms bonded to each other whereas lattices contain atoms, molecules or ions bonded to each other.
Reference:
1. Libretexts. “Ionic Structures.” Chemistry LibreTexts, National Science Foundation, 19 June 2017. Available here
2. Helmenstine, Anne Marie, Ph.D. “What Is a Molecule?” ThoughtCo, Jun. 11, 2018. Available here
Image Courtesy:
1.”Water molecule 3D”By Dbc334 (first version); Jynto (second version) – Water-3D-vdW.png, (Public Domain) via Commons Wikimedia
2.”Sodium chloride crystal”By H Padleckas (Public Domain) via Commons Wikimedia