There are several Gothic characteristics seen in Mary Shelley's novel Frankenstein. According to criticism, Gothic literature contains the themes of "terror and horror," "appearance and reality," "confinement," and "justice and injustice" (eNotes, "Gothic Literature-Themes"). Another important characteristics of Gothic literature is the setting. The setting of most Gothic literature is "generally set...in wild landscapes; in large, often ruined, castles; and/or in subterranean labyrinths" (eNotes-"Gothic Literature-Style").
As for the Gothic elements depicted at the end of chapter seven of Frankenstein, this chapter illuminates the terror and horror associated with the death of an innocent. William, Victor's younger brother, has been murdered. The family, in their attempts to find William (prior to the discovery of his body), searched the vast landscape. While not exactly a "subterranean labyrinth," the search was exhaustive and resulted in horror.
The Frankenstein family did not wish to acknowledge William's death. Instead, they would rather it have been an apparition. Unfortunately, it was a reality for both William and the Frankenstein family.
Another theme typically seen in Gothic literature becomes apparent when the accusations against Justine are made. This speaks to the theme of justice and injustice. While readers are very aware of the identity of the murderer, the people of the town are not. All they are in search of is justice. Unfortunately, they fail to find true justice in making accusations against the wrong person.
The final theme, typical of Gothic literature, is confinement. Given that Victor is far from home, he is confined from the rest of his famliy and their grief. Not to say that Victor does not grieve; in fact, he does.Unfortunately, his distance from his family has confined him from sharing in their collected sadness and horror.