The embrittling/strengthening effects of segregated sp elements in the 3rd, 4th and 5th period (Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te) at the Sigma5(210) grain boundary (GB) in fcc nickel have been investigated using density functional theory. We predict Si as a GB cohesion enhancer, Al and P have none or minimal strengthening effect and S, Ga, As, Se, In, Sn, Sb and Te are GB embrittlers in Ni. We also analyze the segregation enthalpy of all impurities. It turns out that Al, Ga, In, Sn, Sb and Te are substitutional and Si, P, S, Ge, As and Se interstitial impurities at the GB in Ni.