The term 'chemical symbols' refers to the shorthand notation used to represent elements in the periodic table. The two chemical symbols given in the crossword solutions are FE for IRON and NE for NEON. IRON is a chemical element with the atomic number 26 and is represented by the symbol FE. It is a metal that is abundant in the Earth's crust and is an essential component of hemoglobin, which carries oxygen in the blood. NEON is a chemical element with the atomic number 10 and is represented by the symbol Ne. It is a noble gas that is found in trace amounts in the atmosphere and is used in NEON lighting.