Identify each material as a compound or a mixture. caffeine contains hydrogen, carbon, nitrogen, and oxygen atoms in a fixed ratio.

caffeine is a compound.

Explanation:

1) As stated caffeine contains hydrogen, carbon, nitrogen, and oxygen atoms in a fixed ratio.

2) The definition of compound is a pure substance formed by chemical bonding of two or more fifferent elements. That means a defined ratio of the elements in the compound, which conferes uniform and equal properties to every part of the compound.

Some examples of compounds are salt (NaCl), water (H2O), vinegard (CH3 COOH).

A mixture combines several elements or compounds, not bonded by chemical bonds but mixed in ratios which may vary.

Order of filling levels and sublevels of electrons: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²3f¹⁴5d¹⁰6p⁶for an element with 5 electrons in the 3d energy level: full configuration: 1s²2s²2p⁶3s²3p³.