Final answer:
The sociological concept associated with significant change leading to 'normlessness' is anomie, as defined by Émile Durkheim, describing a state of weakened collective norms. Emergent norm theory by Turner and Killian also relates to the fluidity of social norms in crowds.
Step-by-step explanation:
A sociological concept that captures the idea of significant change and resulting "normlessness" is anomie. Defined by sociologist Émile Durkheim, anomie occurs in times of social uncertainty, such as during war or dramatic economic changes. It describes a state where collective norms are weakened and previous social frameworks no longer govern the behaviors and expectations of individuals. Particularly during the transition from mechanical to organic solidarity, as societies become more complex, the disruption of traditional norms can lead to a sense of isolation and disconnection, which is eventually mitigated by the establishment of new norms.
Another related concept is emergent norm theory, developed by sociologists Ralph Turner and Lewis Killian. This theory posits that the norms experienced by individuals within a crowd are diverse and can change rapidly in response to external factors, emphasizing the fluid nature of social norms and the role of individual perceptions.