Question

What is meant by 1s electrons shields 2s electrons

Answer 1

Electrons in an atom can shield each other from the pull of the nucleus. This effect, called the shielding effect, describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. The more electron shells there are, the greater the shielding effect experienced by the outermost electrons.

Hete 1s electrons are in a orbit closer to nucleus .Ans 2s electrons are in the outer orbit than 1s electrons. So the 1s electrons hinders the attractive force between nucleus and 2s electrons. So the force of attraction of 2s electrons and nucleus decreases. This is meant by 1s elections sheids the 2s electrons .That is 1s electrons act like a sheild to 2s electrons to the attractive force from nucleus