Large date 1982 no mint mark penny

I'm new at coin collecting, I don't fully understand the 1982 penny differences.  I have a large date no mint mark 1982 penny that weighs 2.54

All my other 1982 large dates weigh 3.11. But they have a D mint mark. My small date 1982 D pennies weigh 2.5 grams..why does this large date  no mint mark 1982 weigh 2.54 grams like the small date?? It's a bit confusing..

I'd appreciate any info, thank you.