Define a primary source and secondary source

primary source: documents the result of original researche.

: is written by those who have conducted researche.

: includes firsthand information about their methodologies, data, results or conclusions.

Secondary source: summarizes, compares, critiques or interprets the primary source.

Explanation:

Primary source is the research articles published in scholarly, peer reviewed journal.

Secondary source is the summarises, critiques or interpretations of primary source.

each  column  of the  table  is called a group. elements in a group share similar properties. groups are  read  from  top  to  bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o.  2. 3. 4. 5. 6. 7. 8. 9.  2. beryllium. 9.012. 4.  sodium. 22.990.  11. 3.  magnesium. 24.305.  12.  potassium. 39.098.  19. 4.  calcium. 40.078.  20. i guess  i  

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