Unit 5 - Chemical Periodicity

Trends in Atomic Size - Group Trends

Atoms get bigger as they go down a family because they are adding energy levels.

Trends in Atomic Size - Periodic Trend

Atoms ten to get smaller as you go across the period from left to right because you are adding electron in same energy level and the nuclear charge is increasing. This causes valence electrons to come closer to atom.

Atomic Radius

Half the distance between two nuclei of same element

Nuclear Shielding

Electrons stays the same

Nuclear Pull

Protons increases

Trends in Ionic Size - Group Trend

Get larger as you do down family. More energy levels

Trends in Ionic Size - Periodic Trends

Cations and Anions

Cations

Smaller than the atoms because they lose electrons and get smaller as you lose

Anions

Larger than the atoms because they gain electrons and they get smaller as they gain fewer electrons.

Trends in Ionization Energy - Group Trend

Decreases as you go down family, getting bigger

Trends in Ionization Energy

The energy needed to remove an electron from an element in gaseous state

X(g) -> X+(g) + e-

Trends in Ionization Energy - Periodic Trend

Increases along the period because atoms are getting smaller and the valence electrons are closer/held more tightly by the nucleus.

More than one energy level can be removed

Ionization energy increases, removing electrons from a positive ion after first electron is removed.

Labeling of Ionization Energy

Number of electron being removed, 1st, 2nd, 3rd ionization energy

Trends in Electronegativity

Attraction for a pair of electrons by a shared bong
Composite Number
Linus Pauling
F has the highest and Cs has lowest

Trends in Electronegativity - Group Trend

Decrease down a family

Trends in Electronegativity - Periodic Trend

Increase as atoms get smaller across period

Electron Affinity

The energy change associated with the gaining of an electron.

Melting Point

The changing of a solid to a liquid, particularly of metals.

Melting Point - Group Trend

Decreased down a family as they get larger

Melting Point - Period Trend

Increases across the metallic period as there are more valence electrons to hold metal together. Takes more energy.