5 & 6: Columbic Attraction and Periodic Trends

Question 1

Coulombic Attraction

Answer 1

The attraction between oppositely charged particles.

Ex. The protons in the nucleus of an atom have attraction for the electrons surrounding the nucleus.

Question 2

Which element (Sodium, Aluminum, or Chlorine) has the strongest attraction for its outermost electrons?

Answer 2

Chlorine, due to its larger nucleus (more protons).

Question 3

Which is more important in deciding Columbic Attraction: distance or number of protons?

Answer 3

Distance. Nucleus size only matters where there is the same distance (same row).

Question 4

Shielding Effect

Answer 4

Valence electrons are influenced also by the repulsive power of neighboring and core electrons. Core electrons reduces the attractive power of the nucleus, reducing the effective nuclear charge (Zeff)

Question 5

Atomic Radius

Answer 5

Decreases across a row due to a tighter hold of valence electrons from the nucleus

Increases down a column due to more core electrons (additional energy states or “rings”)

Question 6

Ionization Energy

Answer 6

Increases across a row since it becomes harder to break off an electron due to stronger nuclear attraction.

Decreases down a column due to additional shells being added (further atomic radius).

Question 7

Electronegativity

Answer 7

Increases across a row due to increasing nuclear attraction.

Decreases down a column due to lighter nuclear attraction when further away from the nucleus.

Question 8

Effective Nuclear Charge (Zeff)

Answer 8

Increases across a period since atom size does not change and more protons add to the nuclear attraction, but is same going down due to shielding effect which cancels out the additional protons.

Question 9

Electron Affinity (energy change associated with adding electrons)

Answer 9

Increases across a row and decreases down a column.

Question 10

Isoelectronic Ions

Answer 10

Ions with the same number of electrons.

Both cations and anions tend to achieve closest Noble Gas configuration.

Question 11

Radius of Cation and Anions:

Answer 11

Losing electrons means the cations get smaller.

Gaining electrons means the anions get larger.

Question 12

4s and 3d orbital (adding and losing electrons)

Answer 12

While 4s orbital is filled before 3d, this means 4s also loses electrons before 3d.

Ex. Se+ is [Ar] 4s1 3d1
–> Se2+ is [Ar] 3d1