Why do elements at the bottom left of the periodic table have low ionization energies?

Answer 1

Bottom left elements of the Periodic Table have low first ionization energies. Ionization energy is the minimum energy required to remove the outermost electron from an isolated gaseous atom to covert it into monovalent ion. Ionization energy depends on the electrostatic force of attractionbetween the nucleus of the atom and the outermost or valence electron. More the attraction more the energy needed.

First of all the size of atoms of bottom left elements is larger as compared to other elements. Therefore, the electrons in the valence or outermost shell are at large distance from nucleus and feel less electrostatic force of attraction and are easier to remove. With increase in atomic number the number of inner shells of electron increases as a result of which shielding or screening effect increases. Since these elements have more number of inner shells so screening effect is more which further decreases the force of attraction. However, the high nuclear charge should cause more attraction but combined effect of nuclear charge, screening effect and large distance from nucleus result in decrease in attraction. Decreased attraction means it will be easier to remove valence electron and ionization energy will be low. It should be noted that only first ionization energy in case of group 1 elements and first and second ionization energy in case of group 2 elements is low but once the atoms of these elements acquire noble gas configuration by losing electrons their ionization energy becomes unusually high.

Answer 2

Beacuse they have 1 or two at most outer electrons wanting to be removed so the element can get a stable octet - and these electrons are far away from the nucleus because of the size (lower left of table) and hence the electrons are very easy to remove and thus low ionization energy (little energy required to remove them)

Answer 3

Good question - it's because down toward the bottom the PTE, you're dealing with elements with electrons way out in the 4th, 5th, even the 6th energy levels. Those electrons are so far (relatively speaking) from the atomic nucleus, that the attraction between nucleus and valence electrons is quite a bit weaker than in elements with fewer energy levels. This means that for the elements farther down the table, it takes less energy to strip those electrons away. This translates to a lower ionization energy.

Answer 4

The bottom left of the periodic table of elements features elements with low ionization energies because of the way the periodic table is set up, by the number of valence electrons (elements farther left are more reactive). It takes very little energy to move the few excess electrons away to other atoms.