This interactive activity from ChemThink describes covalent bonding—a type of chemical bond that involves the sharing of electrons. Investigate the attractive and repulsive forces that act on atomic particles and how the sharing of electrons can keep atoms together. See how two hydrogen atoms interact with each other to create a covalent bond. Learn about trends in the periodic table and how electrostatic potential energy determines the bond length. Also, learn about naming conventions for covalent compounds.
Follow the instructions closely as you move through this activity! There are some screens where you have to do something before you can move onto the following screen.
According to the atomic model, electrons orbit the atom's nucleus at specific levels, or shells. Electrons in the outermost shell, which are involved in chemical bonding, are known as valence electrons. Since atoms are more stable when their outer shell is filled, they tend to lose, gain, or share electrons to complete their outer shell.
Two common types of chemical bonds—ionic and covalent—differ in how the atoms achieve full outer shells. In an ionic bond, electrons transfer from one atom to the other. In a covalent bond, the atoms share electrons. Whether a bond is ionic or covalent depends on the electronegativities of the atoms involved.
Electronegativity is the measure of an atom's ability to attract electrons. Some atoms tend to lose electrons, while others are more likely to gain them. Elements with low electronegativity, such as metals, have outer shells that are almost empty; these elements give up electrons fairly easily. Elements with high electronegativity, such as nonmetals, have outer shells that are mostly full; these elements tend to hold on to their electrons. In general, elements on the left of the periodic table have low electronegativities, whereas elements on the right side of the table have high electronegativities. Ionic bonds form when the electronegativities of two atoms vary significantly; covalent bonds form when the electronegativities of the atoms are similar.
A single atom is held together by the attraction between the protons in its nucleus and its orbiting electrons. When two atoms approach each other, each nucleus also attracts the other atom's electrons. The sharing of valence electrons in covalent bonding is the result of both atoms "fighting" for the electrons, with neither one "winning." Consequently, the atoms are effectively bonded together.
If the atoms get too close, they repel each other because of proton-proton and electron-electron repulsion. A molecule is most stable when its electrostatic potential energy is at a minimum—in other words, when its atoms are located at a distance where the proton-electron attractions balance these repulsions. At this distance, the atoms can share their valence electrons and form a covalent bond.
Covalent bonds can be formed with one or more pairs of electrons. A single bond is the sharing of one electron pair. It is also common to have double bonds (two pairs of electrons shared between the atoms) and triple bonds (three pairs of electrons shared between the atoms).
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.