The most common gas in the atmosphere, nitrogen, is made of two nitrogen atoms bonded by a triple bond. In some cases, three covalent bonds can be formed between two atoms. Similarly, in carbon dioxide (CO 2), two double bonds are formed between the carbon and each of the two oxygen atoms (Fig. For example, in the formation of the oxygen molecule, each atom of oxygen forms two bonds to the other oxygen atom, producing the molecule O 2. Sometimes two covalent bonds are formed between two atoms by each atom sharing two electrons, for a total of four shared electrons. Figure 2.30 A has additional examples of single bonds. For example, water, H 2O, has two single bonds, one between each hydrogen atom and the oxygen atom (Fig. A molecule can have multiple single bonds. A single bond is defined as one covalent bond, or two shared electrons, between two atoms. In the formation of a covalent hydrogen molecule, therefore, each hydrogen atom forms a single bond, producing a molecule with the formula H 2.

Hydrogen is shown in Fig 2.28 with one electron. When an electron, or dot, from one element is paired with an electron, or dot, from another element, this makes a bond, which is represented by a line (Fig. The oxygen atom forms two bonds, one with each of two hydrogen atoms therefore, the formula for water is H 2O. The single electrons match up to make pairs (Fig. One oxygen atom can share its unpaired electrons with two hydrogen atoms, each of which need only one additional electron. To fill its valence shell, oxygen needs two additional electrons, and hydrogen needs one. In the formation of water, an oxygen atom has two unpaired electrons, and each hydrogen atom has one (Fig. First, determine how many atoms of each element are needed to satisfy the octet rule for each atom. 2.29 gives an example of how to make a Lewis dot structure. In order to form a covalent bond, each element has to share one unpaired electron.įig. The number of bonds that each element is able to form is usually equal to the number of unpaired electrons. The first four electrons are placed as single electrons, then the remaining four are paired. There can be up to eight dots, for eight valence electrons. 2.28 Dots are placed around the symbol of the element to represent the number of valence electrons in the element. A table of Lewis dot symbols of nonmetal elements that form covalent bonds is shown in Fig. Lewis dot structures are one way to represent how atoms form covalent bonds. It takes two electrons to make a covalent bond, one from each bonding atom. Covalent bonding is the type of bond that holds together the atoms within a polyatomic ion. Covalent bonding generally happens between nonmetals. This is a covalent bond, a bond in which atoms share electrons. This is how hydrogen and oxygen share electrons they each have an electron that they can share in a bond. The bones represent one of their electrons. The two ions are held together by strong electrostatic force of attraction.Imagine two puppies, each with a bone (Fig. Sodium atom changes into Na+ ion while the chlorine atom changes into Cl ion.

During the combination of sodium and chlorine atoms, the sodium atom transfers its valence electron to the chlorine atom.It has a tendency to gain one electron and thereby acquire the electronic configuration of the nearest inert gas, argon (2, 8, 8). Chlorine has seven electrons in its valence shell.It has a tendency to lose one electron to acquire the electronic configuration of the nearest inert gas, neon (2, 8). Sodium has one electron in its valence shell.The electronic configurations of sodium and chlorine are:.The bond formed by the complete transfer of one or more electrons from an electropositive atom to an electronegative atom, leading to the formation of ions that are held together by electrostatic attraction is called an ionic bond or electrovalent bond.

Nacl ionic or covalent