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Periodic Trends Atomic Radius Ionization Energy Electronegativity Metal Reactivity
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Periodic TrendsPeriodicity Unit
Part 3
Periodic LawWhen arranged by increasing atomic
number, the chemical elements display a regular and repeating pattern of chemical and physical properties.
Periodic TrendsAtomic RadiusIonization EnergyElectronegativityMetal Reactivity
Atomic Radius DefinitionOne half the distance between the nuclei
of two atoms of the same element when the atoms are joined
Atomic Radius Trend Left to right (across a row) the atomic
radius decreases Top to bottom (down a column) the atomic
radius increases
Atomic Radius Horizontal Trend Decreases from left to right
The positive protons are pulling the outer negative electrons more closely to the nucleus because the nuclear charge is increasing (due to additional protons) and the outermost electrons are not being shielded from it (due to electrons being added to the same energy level)
Atomic Radius Vertical Trend Increases from top to bottom
The atom is getting larger because the electrons are being added to higher principle energy levels and the outermost electrons are being shielded from the strong nuclear charge
Shielding electrons filling in the orbitals between the nucleus and outer electrons help block the attraction of the positive nucleus so outer electrons are NOT being pulled toward the nucleus
Ionization Energy DefinitionThe energy needed to remove an
electron from an atom
Ionization Energy Trend Left to right (across a row) the ionization energy
increasesTop to bottom (down a column) the ionization
energy decreases
Ionization Energy Horizontal TrendIncreases from left to right
The increased nuclear charge of each successive element produces an increased hold/pull on the valence electrons
This increased pull makes it more difficult for an electron to be removed and therefore requires more energy
Ionization Energy Vertical TrendDecreases from top to bottom
As the size of the atom increases, nuclear charge has a smaller effect on the valence electrons (since they are further from the nucleus)
Less energy is required to remove an electron from this energy level
Electronegativity Definition The ability of an atom to attract
electrons when it is in a compound.
Electronegativity Trend Left to right across a row the
electronegativity increases (not including the noble gases)
Top to bottom down a column the electronegativity decreases
Electronegativity Horizontal TrendIncreases from left to right
Atoms toward the right are more inclined to gain electrons and are more likely to pull electrons toward itself in a bond
Electronegativity Vertical TrendDecreases from top to bottom
There is an increased distance between the valence electrons and nucleus so the attraction of the nucleus for the bonding electrons is minimized
Metal Reactivity Definition The tendency of a metal to undergo
a chemical reaction
Metal Reactivity TrendLeft to right across a row the reactivity for
metals decreasesTop to bottom down a column the reactivity
for metals increases
Francium is the most reactive metal
Metal Reactivity Horizontal and Vertical Trend Horizontal Trend:
Decreases left to rightMetals still want to give away valence electrons
but since they have more of them to get rid of, more energy is required
Vertical Trend:Increases from top to bottom As go down a group, outermost electrons are
further from the nucleus (less nuclear pull) so it is easier for them to be lost (requires less energy)
Alkali Metal Reactivity (down a group)http://
edtech2.boisestate.edu/lindabennett1/502/Periodic%20Table%20e%20config/PTable_trends%20around%20table.html
Nonmetal Reactivity Trend Reactivity decreases from top to bottom
Higher up = atoms with the higher electronegativity resulting in a more vigorous exchange of electrons. Fluorine is the most reactive nonmetal!
Reactivity increases from left to right the closer you get to fulling your s- and p- orbitals the
more motivated you are to do so.