Chemical Periodicity

Classifying by e- Configuration Noble Gases – Elements in which the outermost s and p sublevels are filled Representative Elements – Outermost s or p sublevel is only partially filled Transition Metals – Metallic elements in which the outermost s and p sublevel contain electrons Inner Transition Metals – Metallic elements in which the outermost s and nearby f sublevel generally contain electrons

Trends in Atomic Size Group Trends – Atomic size generally increases as you move down a group Electrons are added to the next higher energy level as you move down Periodic Trends – Atomic size generally decreases as you move left to right across a period More protons pull the outermost electrons closer

Trends in Ionization Energy Group Trends – Ionization energy decreases as you move down a group The outermost electron is farther from the nucleus and easier to take Periodic Trends – Ionization energy increases as you move left to right across a period Greater attraction of the nucleus

Trends in Ionic Size Group Trends - Positive ions are always smaller than the neutral atoms from which they form (loss of outer shell electrons) Negative ions are always larger than the neutral atoms (gain of electrons and less attraction) Periodic Trends – size increases from left to right

e- F- F e- Li+ Li Cl- e- Cl e- Na+ Na

Trends in Electronegativity The electronegativity of an element is the tendency for the atoms to attract electrons when they are chemically combined with atoms of another element Group Trends – electronegativity decreases moving down the group Periodic Trends – electronegativity increases moving left to right across a period

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