This article discusses atomic states and the three types of atomic bonding: ionic bonding, covalent bonding, and metallic bonding.
Chemical activity is simply the bonding of one atom with another through the gaining, losing, or sharing of valence electrons. Some chemical activities occur naturally, but most of them are induced through an outside force. Valence electrons of different atoms are frequently bonded together to form stabilized molecules or compounds.
Atomic States
Chemical activity depends on the number of electrons in the outermost energy level of the valence shell. A shell with a full complement of electrons tends to be in a preferred atomic state. A full complement of electrons means that the highest number of electrons is allotted to an energy level. For example, a full complement of electrons for the s-level is 2, and a full complement of electrons for the p-level is 6. An atom with a full complement of electrons in its outermost energy level is in a stable state and is generally called a stabilized atom. A stabilized atom will not release electrons under normal conditions.
Helium is an example of an element whose atoms are in a stable state. Helium has two protons and two neutrons in its nucleus. Two electrons orbit the nucleus in the s-level of the K-shell. The full complement of electrons for the s-energy level is 2; therefore, helium is in a stable state.
Figure 1. The Two States of an Atom
Hydrogen is an atom that contains one proton in its nucleus. This proton, like all protons, possesses a positive charge. Remember that the number of electrons that exist in an atom tends to match the net positive charge of the nucleus. Hydrogen, therefore, has one electron in its structure. This electron orbits the nucleus in the K-shell in an s-type orbital pattern. If no additional energy is added to the electron, the atom is considered to be in its ground state or lowest energy level. Atoms in the ground state have a stronger tendency to bond in order to reach a stable state. Hydrogen does not have a full complement of electrons in the s-energy level; therefore, hydrogen is in a ground state. If energy is provided, an electron may jump to a higher energy orbit and cause the atom to go into an Excited state.
Ionic Bonding
Ionic bonding is the process of bonding atoms through electrostatic force. Electrostatic force occurs through the attraction of opposite net charges between two atoms. This process typically occurs between atoms of different elements. Ionic bonding, therefore, creates a compound. You should recall that a compound is a combination of two or more elements to form an entirely different material.
Figure 2. General Process of Ionic Bonding
The atomic structure of lithium lends itself very well to compound formation. A compound of lithium and hydrogen is called lithium hydride. In this compound, the valence electron of lithium is transferred to the K-shell of a hydrogen atom. The lithium atom takes on a +1 charge because it has lost an electron. It is now considered to be a positive lithium ion.
The lithium atom becomes a positive ion, and the hydrogen atom becomes a negative ion. The net charges of the ionized particles bond the atoms through electrostatic force. An ion is an atom that has lost or gained an electron. If an atom loses an electron, it becomes positively charged. Gaining an electron causes an atom to be negatively charged. For example, when lithium hydride is formed, the hydrogen atom gains an electron and becomes a negative ion with a charge of −1. Since unlike charged particles have an attracting power, a single molecule of lithium hydride is formed by this combination of atoms. Compounds formed in this manner are described as electrovalent combinations or ionic bonded mixtures. The net charges of the ionized particles bond the atoms and create a compound.
Table salt is a good example of ionic bonding that occurs naturally. The sodium (Na) atom donates its one valence electron to a chlorine (CI) atom, which has seven valence electrons. On acquiring the extra electron, chlorine becomes a negatively charged ion, while the sodium atom becomes a positively charged ion. Since unlike charges attract, the positive sodium (Na+) and negative chlorine (CI−−) ions are bonded together by an electrostatic force.
Copper oxide (Cu2O) is also an example of ionic bonding. The valence electrons of two atoms of pure copper (Cu) are transferred and combined with one atom of oxygen (O). Copper is a good electrical conductor. Copper has one valence electron in the s-level of the N-shell. Oxygen has six valence electrons in the L-shell; two of these are in the s-level and four are in the p-level. The combination of two copper atoms and one oxygen atom forms a stable copper oxide compound. The two copper valence electrons combine with four electrons in the p-level of the L-shell of oxygen to form a full complement of six electrons. The stability of this compound makes copper oxide a good insulating material.
Covalent Bonding
Another form of bonding can take place when the outermost shell of an atom is partially filled. The atoms in this form of bonding position themselves so that the energy levels of their valence electrons combine. This form of bonding is called covalent bonding or electron pair bonding. No ions are formed in covalent bonding because the valence electrons are shared between the atoms. These electrons alternately shift back and forth between each atom.
Figure 3. General Process of Covalent Bonding
A covalent force is, therefore, established between the connecting electrons. The covalent force bonds the atoms in a simulated condition of stability.
Two hydrogen atoms are bonded together due to covalent bonding. In such scenarios, the K-shells of each atom overlap so that their electrons can be shared. In doing so, both have the equivalent of a full complement of electrons in their s-level.
The molecules of common gases, such as oxygen and nitrogen, are frequently held together by covalent bonding. Semiconductors such as carbon, silicon, and germanium are also bonded by this process. Covalent bonding is much stronger than ionic bonding.
Metallic Bonding
Metallic bonding is an internal force that holds atoms loosely together in a conductor. It occurs in good electrical conductors. An electrical conductor such as copper has one electron in the s-level of its N-shell. This electron is easily influenced by outside energy and has a tendency to wander around the material between different atoms. On leaving one atom, it immediately enters the orbital of another atom. The process is repeated until the outside energy is removed.
Figure 4. General Process of Metallic Bonding
When an electron receives enough energy to leave an atom, it causes the original atom to become a positive ion. In metal, this process occurs at temperatures of $25^{o}C$. The process takes place randomly. This means that one electron is always associated with an atom but is not in one particular orbital path. As a result, a large number of the structural atoms of a piece of copper tend to share valence electrons.
In metallic bonding, there is a type of electrostatic force between positive ions and electrons. In a sense, electrons float around in positively charged clouds that surround the positive ions. This floating cloud of electrons tends to bond itself randomly to the positively charged ions.
Atomic Bonding Review Question
- Atoms in a(n) _____ state have a stronger tendency to bond in order to reach a stable state.
- Atoms in a(n) state will not release electrons under normal conditions.
- When two or more elements are used to form a different material, it is called a(n) .
- The process of bonding atoms through an electrostatic force is called bonding.
- Table salt and copper oxide are examples of bonding.
- The condition of stability is simulated when atoms are bonded.
- Individual atoms of silicon are frequently connected together by bonding.
- The bonding occurs in good electrical conductors.
Answers
- ground
- stable
- compound
- ionic
- ionic
- covalently
- covalent
- Metallic
Atomic Bonding Key Takeaways
The different types of atomic bonding—ionic, covalent, and metallic—are fundamental in determining the properties and behaviors of materials, making them crucial to a wide range of applications. Ionic bonding is vital in the formation of salts and compounds used in various industrial processes, while covalent bonding is central to the creation of stable molecules like water and essential organic compounds. Metallic bonding plays a key role in the functionality of conductors and materials used in electronics and construction.