1. HW 8-12 Size Trends involving ions
Periodic Trends
HW 8-12 Size Trends involving ions

2. Size of Neutral Atom vs + Ion

3. + ion has lost an energy level compared to neutral atom

4. Size comparison +1 vs +2 ion

5. Size comparison +1 vs +2 ion+4 +3

6. Size comparison +1 vs +2 ion+4 +3
Same electron configuration (1s2); Different # of protons;
4 protons of Be+2 exerts stronger attraction
than 3 protons of Li+1

7. Ionic Radii
Same trend as atoms, only with negative ions (anions) larger than positive ions (cations).

8. Size of neutral atom vs negative ion
Protons:
e- config: 9 9
1s22s22p5
1s22s22p6
Same # of protons; 9 electrons vs 10 electrons. More repulsion within e- cloud with greater number of electrons spreads out e- cloud = bigger
Link to Phet Charges

9. Ion vs. Atom Size

10. 9 10 11 More protons pulling on same # of electrons = smaller atom
Isoelectronic Series
An isoelectronic series contains atoms/ions with the same number of electrons.
F-1: # protons =
Ne: # protons =
Na+1: # protons = 9 10 11
More protons pulling on same # of electrons = smaller atom

11. F-1, Ne, and Na+1 all have ______ electrons.
Isoelectronic Series
An isoelectronic series contains atoms/ions with the same number of electrons. For example,
F-1, Ne, and Na+1 all have ______ electrons.
When comparing the atomic radii in such a series, the key is to look at the number protons for each:
The greater the number of protons pulling on the same number of electrons, the ______________ the radius.
_______ > _______ > _______ 10
smaller
F Ne Na+1

12. Video solution to problem #4 Mg+2, Al+3, N-3, O-2
Isoelectronic Series
Video solution to problem #4 Mg+2, Al+3, N-3, O-2
Animation
5) Br-1 > Kr > Rb+1
Ratio of P/e-: Br: 35:36 Kr: 36:36 Rb: 37:36
Increased + charge relative to – decreases size