Chem Notes

Essay by legend2363High School, 11th gradeA-, November 2014

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Periodic Table:

Nuclear Charge:

Increases across a period (Increase in protons creates a more positive charge)

Increases down a group (Increase in protons creates a more positive charge)

Attractive Force between nucleus and outer electrons:

Increases across a period (Increase in protons)

Decreases down a group (Despite more protons, shells cause 'shielding' weakening the attractions between nucleus and valence electrons)

Electronegativity:

Increases across a period (More protons to attract electrons)

Decreases down a group (Becomes more metallic, meaning it would rather give away electrons than take it)

Atomic Radius:

Decreases across a period (Increased protons pulls in the electrons closer)

Increases down a group (More shells, meaning larger radius)

Metallic Nature (how easily electrons are given):

Decreases across a period (Electrons are not easily given; more protons)

Increases down a group (More shells reduce attraction, therefore electron is more easily given away)

Conductivity (related to metallic nature):

Decreases across a period (Less metallic)

Increases down a group (More metallic)

First Ionisation Energy (How much energy needed to remove an electron):

Increases across a period (More protons make it harder to lose electrons)

Decreases down a group (Shells reduce attraction, making it easier to lose electrons)

Solubility:

Lattice Solids and Solubility:

Metallic Lattices do not dissolve because the metallic bonds are too strong to break apart

Ionic Lattices can either dissolve or not dissolve:

Some dissolve due to ionic substances being polar and are pulled apart by the polar water molecules

Some do not dissolve as the ionic bonds are too strong

Covalent Molecular Lattices:

Polar molecules dissolve due to attraction of polar water molecules

Non-polar molecules do not dissolve in water but dissolve in non-polar substances

Covalent Network Lattices do not dissolve as the lattices are too strong

Polymers do not dissolve as they are too large

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