The atomic structure represents the shape and arrangement of the subatomic particles within an atom. The arrangement of the atoms or molecules in a crystal liquid or solid is represented by its crystal structure.
The building blocks of all matter are called atoms, and when examined experimentally, they exhibit a complex structure. Understanding the fundamental composition of an atom is important for understanding nearly all chemistry concepts.
Solid substances composed of several atoms or molecules are called crystals. In crystals, specific configurations can be found which are known as crystal structures.
The arrangement of subatomic particles within an atom is described by its atomic structure, whereas the arrangement of atoms or molecules within a crystalline substance is described by its crystal structure.
In this article, we will study about Atomic structure and Crystal structure and the difference between the two.
1. Atomic Structure
Atoms are made up of a very tiny, positively charged nucleus that is surrounded by a field of negatively charged electrons. The nucleus often makes up more than 99.9% of the mass of the atom, although being less than one-tenth the size of the atom.
Positively charged protons and electrically neutral neutrons, makeup nuclei, are bound together by the nuclear force. Although this force is significantly greater than the electrostatic force that holds electrons to the nucleus, its range is only around 1 × 10-15 meters.
1.1 Subatomic Particles
The modern atomic theory states that an atom is made up of subatomic particles known as electrons, protons, and neutrons.
The existence of the electron was discovered by J. J. Thomson in 1897. Within specific energy shells located around the nucleus, negatively charged electrons move in a random pattern. The number and configuration of an atom’s electrons determine the majority of its properties. An electron has a mass of 9.1 × 10-31 kilograms.
We cannot determine the exact location of a single electron since they are constantly moving around the nucleus. We can only state the probability of finding an electron at a particular location which indicates that electrons move in specific shells. From the nucleus to the outside, these electron shells are referred to as K, L, M, N, and so forth.
Electron shells can be further divided into sub-shells. These sub-shells are known by the names s, p, d, and f sub-shells.
The primary subatomic particle that takes part in chemical processes is the electron. Protons and neutrons, however, take part in nuclear reactions.
The proton is one of the two types of particles that can be found in the nucleus. Sir Ernest Rutherford demonstrated in 1919 that the nucleus contains a positively charged particle called a proton. When compared to the electron’s negative charge, the proton’s charge is opposite yet equal to it. The number of protons in the nucleus of an atom determines what kind of chemical element it is. The mass of a proton is 1.67 × 10-27 kilograms.
The other particle present in the nucleus is the neutron. A British scientist named Sir James Chadwick made the discovery. The proton’s mass is shared by the neutron, which has no electrical charge. Due to its lack of electrical charge, the neutron is not attracted to the nucleus or the electron cloud, making it an effective resource for examining the atomic structure.
Even the individual protons and neutrons have internal structures, called quarks. There are six different kinds of quarks. These subatomic particles cannot be liberated or researched separately.
2. Crystal Structure
A crystal structure is any structure that is held together by atoms, ions, or molecules arranged in a highly ordered three-dimensional configuration. The highest level of order that can occur in a solid material is called crystal structure. The term “crystal lattice structure” might be used to describe this configuration.
It consists of a definable chemical composition and ordered structure at the microscopic level creating a 3-dimensional substance.
A crystal structure may be made up of naturally occurring or artificially produced organic or inorganic molecules. Ionic, molecular, covalent, metallic, and other forms of chemical bonding are used to create crystal structures.
2.1 Unit Cell
A unit cell is the smallest component of this ordered structure. This unit cell is a representation of the crystal’s general configuration.
The unit cell has three main proposed structures-
- Simple cubic structure
- Body-centered cubic structure
- Face-centered cubic structure
There are seven different types of crystal formations, which are identified by their symmetry. They are cubic, tetragonal, orthorhombic, rhombohedral, mono-clinic, triclinic, and hexagonal.
There are also crystal structures with names based on the kind of chemical bond that exists within the crystal. They are-
- Ionic crystals: Cations and anions are organized in a repeating, regular pattern to form ionic crystals.
- Covalent network crystals: Atoms or molecules connected to one another by covalent bonds form a network of atoms or molecules in covalent network crystals.
- Metallic crystals: Metal cations are contained within freely flowing electrons in metallic crystals.
3. Difference between Atomic Structure and Crystal Structure
| Atomic Structure | Crystal Structure |
| The arrangement of subatomic particles within an atom is known as its atomic structure. | The arrangement of atoms or molecules in a crystal is known as its crystal structure. |
| The atomic structure is a complicated structure. | A well-organized lattice structure makes up the crystal structure. |
| Protons, neutrons, and electrons are the subatomic particles that make up an atom. | Cations, anions, or metal ions with free electrons make up crystals. |
| All atoms share the same overall atomic structure. | Depending on the elements found in the crystal, each crystal has a unique structure. |
| The mass of the atomic structure is less than the mass of the crystal structure. | The mass of the crystal structure is greater than the mass of the crystal structure due to the higher molecular content. The number of molecular strands in a crystal structure is determined to be more than that of an atom when calculated. |
| An atomic structure is weaker because an atomic structure is bonded by an ionic bond which is weaker and requires less energy to break. | A crystal structure is stronger because crystal structure is bonded with a strong covalent bond between the particles and thus will require more energy to break. |
| An atomic structure is soluble in water. | A crystal structure is insoluble. |
| The atomic structure conducts electricity due to the presence of electrons within it. | A crystal structure lacks free electrons, which limits its ability to conduct electricity. |
Key Takeaways
Key Points
- Understanding atomic structure is essential to understand all aspects of chemistry.
- The crystal structure is crucial for recognizing crystals, understanding their characteristics, and predicting their reactions.
- The atomic structure describes the atoms at an individual level, while the crystal structure describes the arrangement of these atoms in a repeated pattern in solid material.
Key Terms
Sub-shell: An electron shell can be further divided into sub-shells, each of which can contain one or more atomic orbitals. Each orbital can hold up to two electrons with opposite spins. While electrons in various shells or sub-shells have different energies, those in the same sub-shell retain the same energy.
FAQs
What is the main difference between atomic structure and crystal structure?
The main difference between atomic structure and crystal structure is that atomic structure refers to the arrangement of atoms in a single molecule or in a group of molecules, while crystal structure refers to the way in which atoms are arranged in a solid material.
Do all materials have a crystal structure?
No, not all materials have a crystal structure. Amorphous materials, such as glasses, do not have a repeating pattern of atoms in three dimensions, so they do not form a crystal lattice.
How does the crystal structure of a material affect its properties?
The crystal structure of a material can greatly affect its properties, such as its hardness, melting point, and electrical conductivity. Understanding the crystal structure of a material is key to understanding its properties and how it can be used in different applications.
Can you give an example of how atomic structure and crystal structure are related?
One example is in the case of a metal, where the atoms are arranged in a repeating pattern in a crystal lattice. The strength and electrical conductivity of the metal are determined by the way in which the atoms are arranged in the crystal lattice, so the atomic structure and the crystal structure are closely related.
Is it possible to change the crystal structure of a material without changing its chemical composition?
Yes, it is possible to change the crystal structure of a material without changing its chemical composition. This can be done through a process called heat treatment, where the material is heated to a certain temperature and then cooled at a specific rate, causing the atoms to rearrange into a different crystal structure.