The second ionisation energies are higher than the first ionisation energies. This is mainly due to — Periodic Table and Periodicity Chemistry Question
Question
The second ionisation energies are higher than the first ionisation energies. This is mainly due to the fact that after the removal of the first electron, the atom changes into monovalent positive ion. In the ion, the number of electrons decreases but the nuclear charge remains the same. As a result of this, the remaining electrons are held more tightly by the nucleus and it becomes difficult to remove the second electron. Therefore , the value of second ionisation energy. (IE2), is greater than that of the first ionisation energy (IE1). Similarly third ionisation energy (IE3) is greater than that of second IE2.
💡 Solution & Explanation
Step 1: Determine the electronic configurations of beryllium (Be: 1s2 2s2), magnesium (Mg: 1s2 2s2 2p6 3s2), and calcium (Ca: 1s2 2s2 2p6 3s2 3p6 4s2). Step 2: Compare their outermost energy levels. All three elements have two s-electrons in their outermost shells, are classified as alkaline earth metals, and belong to group 2 of the periodic table. Step 3: Beryllium has only 4 electrons total, and its outer energy level (n=2) contains no p-orbitals or p-electrons. Therefore, containing a pair of p-electrons in the outermost energy level is not a shared characteristic.