Chief is related to Tribal. Tribal is derived from Tribe. Tribe is a synonym of Folk. Folk is a synonym of People. 
Physics is a different concept from Chemistry. Chemistry is related to Silver. Silver is related to Buddy. 
Chief <--RelatedTo--> Tribal --DerivedFrom--> Tribe <--Synonym--> Folk <--Synonym--> People 
Physics <--DistinctFrom--> Chemistry <--RelatedTo--> Silver <--RelatedTo--> Buddy 