PERIODICITY ! Name: ______
-trends in properties of elements across a period (left-right) & within a group (top-bottom) trends

- based upon COULUMBIC FORCE OF ATTRACTION
Formula Fe = ke /(q1) (q2)/ Fe = electrostatic force (Newton, N)
r2 ke = proportionality constant ≈ 8.9 x 109 N m2/C2
q1 & q2 = particle charge amount (Coulomb, C)
r = distance between the charged particles (m)

Amount of Charge Distance between charges

1) EFFECTIVE NUCLEAR CHARGE (ENC):
- amount of the attraction force between (+) & (-) charge (Coulomb Force of Attraction)
- Formula: ENC = # protons - # core (aka ______/______) electrons Ex: Mg (#12) = 12 p+ – 10 core electrons = +2
S (#16) = 16 p+ – 10 core electron = +6
- Across the period, effective nuclear charge ______due to ______
- With in a group/family, shielding effect ______due to ______
2) SHIELDING EFFECT:


- kernel e– shield valence e– from attractive force of the nucleus
- caused by kernel and valence e– repelling each other

- Across the period, shielding effect ______Why? ______
- With in a group/family, shielding effect ______due to ______

Atomic Radius the size of a ______atom

- Across the period, atomic radius ______Why? ______

- With in a group/family, atomic radius ______Why? ______

Example:
Place the following elements in order from smallest to largest atomic radius & explain why? C, O, Sn, Sr

Ionization energy: the energy required to remove an e– from an atom

- Across the period, ionization energy ______Why? ______
- With in a group/family, ionization energy ______Why? ______

Equation: M + 1st I.E. à M1+ + e–

removes 1st e–

M1+ + 2nd I.E. à M2+ + e–

M2+ + 3rd I.E. à M3+ + e–

Each successive ionization requires more energy than the previous one. Why? ______


Example:

Place the following elements in order from lowest to highest 1st ionization energy and explain why? Al, Ar, Cs, Na


DISCLAIMER: Why does magnesium, phosphorus and zinc exhibit slightly higher 1st ionization energies than the
general trend within each of their periods?

Ionic radius: the size of an ion with ___ or ___ charge (aka ______# )
Oxidation Number - most common ______it will form.
Group 1: ______Group 2: _____ Group 16: ______Group 17: _____


Cations Anions

Ca atom Ca2+ ion Cl atom Cl1– ion

20 p+ 20 p+ 17 p+ 17 p+

20 e– 18 e– 17 e– 18 e–


Cations are ______anions are ______

ISOelectric Species: ______
Example: O2- , F1-, Ne, Na1+, Mg2+ - This isoelectric species has ______electrons.


Example:
What is another isoelectronic series of five elements? _____, _____, _____, _____, _____