Question

The atomic number of lithium is 3. How many neutrons does an atom of lithium have if it is represented by the symbol shown below? 7Li

Answer 1

So... for the element of LITHIUM, you already know that the atomic number tells you the number of electrons. That means there are 3 electrons in a lithium atom. Looking at the picture, you can see there are two electrons in shell one and only one in shell two.

Answer 2

It contains 4 neutrons. Hope this helps!