chemical bond

why bonds form

To understand why chemical bonds form, consider the common compound known as water, or H2 O. It consists of two hydrogen (H) atoms and one oxygen (O) atom. As you can see in the on the left side of the Figure 1.1, each hydrogen atom has just one electron, which is also its sole valence electron. The oxygen atom has six valence electrons. These are the electrons in the outer energy level of the oxygen atom. In the water molecule on the right in the Figure 1.1, each hydrogen atom shares a pair of electrons with the oxygen atom. By sharing electrons, each atom has electrons available to fill its sole or outer energy level. The hydrogen atoms each have a pair of shared electrons, so their first and only energy level is full. The oxygen atom has a total of eight valence electrons, so its outer energy level is full. A full outer energy level is the most stable possible arrangement of electrons. It explains why elements form chemical bonds with each other.

textbook_image

what is a chemical bond

A chemical bond is a force of attraction between atoms or ions. Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds. Q: Why do you think that chemical bonds form? A: Chemical bonds form because they give atoms a more stable arrangement of electrons.

types of chemical bonds

Not all chemical bonds form in the same way as the bonds in water. There are actually three different types of chemical bonds, called covalent, ionic, and metallic bonds. Each type of bond is described below. Click image to the left or use the URL below. URL: A covalent bond is the force of attraction that holds together two nonmetal atoms that share a pair of electrons. One electron is provided by each atom, and the pair of electrons is attracted to the positive nuclei of both atoms. The water molecule represented in the Figure 1.1 contains covalent bonds. An ionic bond is the force of attraction that holds together oppositely charged ions. Ionic bonds form crystals instead of molecules. Table salt contains ionic bonds. A metallic bond is the force of attraction between a positive metal ion and the valence electrons that surround itboth its own valence electrons and those of other ions of the same metal. The ions and electrons form a lattice-like structure. Only metals, such as the copper pictured in the Figure 1.2, form metallic bonds.

instructional diagrams

No diagram descriptions associated with this lesson

questions

valence electrons are the basis of all chemical bonds.

-->  a. true

b. false

in covalent bonds, atoms

-->  a) share electrons.

b) transfer electrons.

c) lose or gain electrons.

d) two of the above

an example of a compound that contains ionic bonds is water.

a. true

-->  b. false

a metallic bond is a bond between a positively charged metal ion and

a) a negatively charged halogen ion.

b) a negatively charged nonmetal ion.

-->  c) the valence electrons of several metal ions.

d) the valence electrons of a halogen ion.

metallic bonds form a lattice-like structure.

-->  a. true

b. false

metals can be involved in

a) covalent bonds.

b) metallic bonds.

c) ionic bonds.

-->  d) two of the above

diagram questions

No diagram questions associated with this lesson