Trends in the Periodic Table The rows are

Trends in the Periodic Table

The rows are called periods (7) The columns are called groups (18)

Atomic Radius n Atomic radius is simply the radius of the atom, an indication of the atom's volume.

Trends in Atomic Size cont. n Group - atomic radius increases as you go down a group. Why? n As you move down the periods atoms get bigger (more p+, n 0, and e-) and they have extra layers of shielding.

Bigger atom and extra shielding = less nuclear attraction

Trends in Atomic Size n Period - atomic radius decreases as you go from left to right across a period. n Why? Extra protons in the nucleus create a stronger force of attraction on the outer electrons.

Stronger nuclear charge & no extra “shielding”

Electronegativity is an atom's 'desire' to grab another atom's electrons.

Electronegativity Trends n Period - electronegativity increases as you go from left to right across a period. n Why? More p+ leading to a stronger nuclear pull with no extra shielding.

Stronger nuclear charge & no extra “shielding”

Electronegativity Trends cont. n n Group - electronegativity decreases as you go down a group. Why? Less ability of the nucleus to attract outer electrons due to added shielding.

period

Ionization Energy n Ionization energy is the amount of energy required to remove the outermost electron(s). n Ionization energy is closely related to electronegativity.

Ionization Energy Trends n Period - ionization energy increases as you go from left to right across a period. n Why? Extra p+s & no extra shielding leads to a stronger hold on the outer electrons.

Stronger nuclear charge & no extra “shielding”

Ionization Energy Trends cont. n n Group - ionization energy decreases as you go down a group. Why? The shielding effect makes it easier to remove the outer most electrons from those atoms that have many layers of electrons.

Ionic Radius vs. Atomic Radius n Metals - the atomic radius of a metal is generally larger than the ionic radius of the same element. n Why? Metals lose electrons to achieve the octet. This creates a larger positive charge in the nucleus than the negative charge in the electron cloud, causing the electron cloud to be drawn a little closer to the nucleus as an ion.

Ionic Radius vs. Atomic Radius Non-metals - the atomic radius of a non-metal is generally smaller than the ionic radius of the same element. n Why? Generally, non-metals gain electrons to achieve the octet. The added electrons repel eachother causing the electron cloud to 'puff out' a little bit as an ion. n

Ionic Radius vs. Atomic Radius

Trends Game!

Reactivity refers to how likely or vigorously an atom is to react with other substances. This is usually determined by two things:

Reactivity How easily electrons can be 1) removed (ionization energy) from an atom 2) or how badly an atom wants to take other atom's electrons (electronegativity)

The transfer/interaction of electrons is the basis of chemical reactions!

Reactivity of Metals Period - reactivity decreases as you go from left to right across a period. Group - reactivity increases as you go down a group Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.

Reactivity of Non-Metals Period - reactivity increases as you go from the left to the right across a period. Group - reactivity decreases as you go down the group. Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.

Summary of Periodic Trends