Chlorophyll contains a porphyrin ring with a central magnesium atom. This is the part of the chlorophyll molecule that absorbs light energy.

Here's a breakdown:

* Porphyrin ring: This is a complex, flat ring-shaped molecule with alternating double and single bonds. It's similar in structure to the heme group in hemoglobin.

* Magnesium atom: Located at the center of the porphyrin ring, this atom is crucial for chlorophyll's ability to absorb light energy.

* Phytol tail: This is a long, hydrophobic chain attached to the porphyrin ring. It helps anchor the chlorophyll molecule within the chloroplast membrane.

The porphyrin ring and the magnesium atom are the primary parts of chlorophyll responsible for its ability to absorb light energy, a crucial step in photosynthesis.