sate the number of electrons lost or gained when the following elements form ions sr
Sr ==> Sr^2+ + 2e
To determine the number of electrons lost or gained when an element forms ions, we need to consider its electron configuration.
The element in question is strontium (Sr), which is located in Group 2 of the periodic table. Since Group 2 elements have two valence electrons, we can expect that strontium will lose these two electrons to form a stable ion.
The electron configuration of strontium is [Kr]5s^2, where [Kr] represents the electron configuration of krypton, the noble gas that precedes strontium. To form a stable ion, strontium will lose the two valence electrons in the 5s orbital, resulting in an ion with a +2 charge.
So, when strontium (Sr) forms an ion, it loses 2 electrons.