Question

you cannot hold a piece of sodium in your hair but you can eat sodium ions in sodium chloride why

Answer 1

sodium is a highly reactive metal so we cannot hold it on our hair because it will start burning as a result of reaction with oxygen but in sodium chloride sodium ion is stable and does do not react further with oxygen as it is already bonded with chlorine thus stable electronic configuration

Answer 2

Here is the answer of your question

As we know that Na is highly reactive element because it has one electron in his outermost shell. So, it has to loose one electron to become a stable element.
But when it react with chlorine then it becomes stable and reches the Noble gas electronic configuration.
From above we can say that we cannot hold sodium. But we can eat it.

Hope it helps you.