What motivated the nations of europe to engage in imperialist activities?

Many European nations were motivated to engage in imperialist activities in order to claim and acquire natural resources unavailable to them in their home countries. For example, the Spanish conquered the Aztecs and Incas in part to claim gold and gem mines in the region. The Belgians colonized the Congo and established brutal plantations to harvest rubber. The British in North America took a great deal of land and killed many Native Americans to establish farms for tobacco.