They have a stronger desire to acquire more electrons. Why? Elements near the top of the period table have few electrons to begin with every electron is a big deal. Group - electronegativity decreases as you go down a group. Elements on the right side of the period table only need a few electrons to complete the octet, so they have strong desire to grab another atom's electrons. As a result, they have low electronegativity. Why? Elements on the left of the period table have 1 -2 valence electrons and would rather give those few valence electrons away (to achieve the octet in a lower energy level) than grab another atom's electrons.

Period- electronegativity increases as you go from left to right across a period.

Why? The shielding affect makes it easier to remove the outer most electrons from those atoms that have many electrons (those near the bottom of the chart).Įlectronegativity is an atom's 'desire' to grab another atom's electrons Group - ionization energy decreases as you go down a group. Elements on the left of the chart would prefer to give up their electrons so it is easy to remove them, requiring less energy (low ionization energy). The means it will require more energy to remove the outer most electron. Why? Elements on the right of the chart want to take others atom's electron (not given them up) because they are close to achieving the octet. Period - ionization energy increases as you go from left to right across a period. It is closely related to electronegativity Ionization energy is the amount of energy required to remove the outmost electron. Additionally, new energy levels of elections clouds are added to the atom as you move from period to period down a group, making the each atom significantly more massive, both is mass and volume. Why? There is a significant jump in the size of the nucleus (protons + neutrons) each time you move from period to period down a group. Group - atomic radius increases as you go down a group. Why? Stronger attractive forces in atoms (as you go from left to right) between the opposite charges in the nucleus and electron cloud cause the atom to be 'sucked' together a little tighter. Period - atomic radius decreases as you go from left to right across a period. Summary of Periodic Table Trends Atomic Radius

Periodic table size trend