To copy formatting:
Range("F10").Select
Selection.Copy
Range("I10:J10").Select ' note that we select the whole merged cell
Selection.PasteSpecial Paste:=xlPasteFormats
copying the formatting will break the merged cells, so you can use this to put the cell back together
Range("I10:J10").Select
Selection.Merge
To copy a cell value, without copying anything else (and not using copy/paste), you can address the cells directly
Range("I10").Value = Range("F10").Value
other properties (font, color, etc ) can also be copied by addressing the range object properties directly in the same way