Final answer:
Two chlorine atoms achieve an octet by forming a single covalent bond, sharing a pair of electrons while each retaining three lone pairs. In ionic compounds, a chlorine atom can gain an electron to form a chloride ion with a complete octet. The Lewis structure for chlorine gas (Cl2) illustrates the shared bonding pair and the lone pairs of electrons.
Step-by-step explanation:
Two chlorine atoms achieve an octet by sharing a pair of electrons through a covalent bond. Each chlorine atom has seven valence electrons and needs one more to complete its valence shell. When two chlorine atoms come together to form chlorine gas (Cl2), they share one electron each, forming a single covalent bond. This shared pair of electrons, known as a covalent bond, fulfills both atoms' octet. Additionally, each chlorine atom also has three lone pairs of electrons that are not shared. These lone pairs, along with the two shared electrons, constitute the full octet for each chlorine atom.
When chlorine forms ionic compounds, such as table salt (NaCl), a chlorine atom achieves an octet by gaining an electron from a sodium atom, thus forming a negatively charged chloride ion with a complete octet.
The Lewis Dot Structure for Cl2
According to the Octet Rule, to draw the Lewis structure for Cl2, we place seven dots to represent the seven valence electrons around each chlorine atom symbol. Then we pair up one set of electrons between the two chlorine symbols to indicate the shared covalent bond. Each chlorine then has six dots plus the shared pair, for a total of eight electrons, fulfilling the octet rule.