Answer:
period 3 and group 3
Explanation:
I'm saying group 3 because that is how I learnt it at school, but if you count it then it's in group 13.
The largest transition metal is copernicium with 112 protons
Antoine Henri Becquerel discovered radioactivity when he was studying
X- rays.
He had been studying phosphorescent uranium ores and hypothesized that they might absorb sunlight and reemit it as X-rays.
His hypothesis was wrong, but his experiments led to the discovery of <em>natural radioactivity</em>.
