Periodicity

the minimum required energy to eject an electron out of a neutral atom or molecule in its ground state

decreases due to increased nuclear shielding

increases due to increased nuclear charge

Be to B, ionization of an electron from the first p orbital makes an ion more stable so requires less energy N to O, ionization of an electron from the only paired orbital makes the atom more stable so requires less energy

trends in the periodic table

The radius of a given atom

atomic radius decreases, this is because each element has an additional proton, creating a greater nuclear charge (more attraction to electrons).

the atomic radius increases as you add an additional energy level.

As you add energy levels to an element, the valence electrons become shielded by the inner core electrons.

The radius of an atom that has gained or lost electrons

• positively charged • lost electrons • radius smaller than parent atom • Groups 1, 2 and 13 • charge is equal to the number of valence electrons. • The more electrons lost the smaller the radius.

• negatively charged • gain electrons • radius larger than parent atom • Groups 15, 16 and 17 • charge is equal to the number of electrons needed to get to 18. • The more electrons gained the larger the radius.

the energy released when an additional electron is attached to a neutral atom or molecule.

As you move across a period, electron affinity increases. The higher the nuclear charge, so the more energy is released when an electron is added. (no trend going down)

a measure of the ability of an atom to attract electrons in a chemical bond to itself.

increases across a period. Smaller atoms with nearly complete electron shells will attract electrons more easily.

decreases down a group. Smaller atoms with nearly complete electron shells will attract electrons more easily.

The wavelength that represents ionization of an electron

The energy required to remove a second or more electron from an atom

Increases, because the number of protons now exceeds the number of remaining electrons (increased attraction!) and electron-electron repulsion decreases. This increases until the next stable noble gas configuration is reached at which point the energy increases sharply!