Inert-pair effect

The inert-pair effect is when some elements in the periodic table, like lead and tin, don't want to give away their outermost electrons even though they should be doing so according to how the periodic table works. It's like when you have a really cool toy and don't want to share it with your friends even though you know you should. This is because these elements' outermost electrons are really close to their nucleus, which makes them harder to remove. It's like when your favorite toy is in your tight grip, it's hard for anyone to take it away from you. This makes these elements seem like they have fewer electrons available for bonding or chemical reactions. It's like having fewer friends to play with because you don't want to share your toy. So, these elements react differently than what we would expect based on the periodic table, and we have to take into account the inert-pair effect when predicting their chemical behavior.