Chapter 7

Valance Electrons are

Electrons that reside in the outermost shell of a atom

how do you find the Valance electrons

Main group is found on the group number of PT

how do you find the Valance electrons for transition metals

e^- in the last and d-subshels are counted as VE unless the d-subshell is full. if the 3d shell is not full then counted but if at 10 then shell before is counted

How do you find the Valance Electrons for main group elements

group number on PT ex: halogens = 7VE

Effective Nuclear Charge (Zeff) is what

electrons, protons, how the charges interact. how the net positive charge that an electron “sees” from the nucleus.

How are VE and e- interact

VE shield from nucleus by core electrons

how are e- reacting to other e-

the e- are going to be repulsed by other e-

how are e- and protons in the nucleus

e- are attracted by p⁺ in the nucleus

How are VE and other VE interact

VE shield other VE (only weakly)

What do you calculate Zeff

Zeff= Z(number of protons)-S(shielding factor core electrons)

VE in mg calculate the Zeff

Z-S= 12 protons - 10 core electrons) = +2 (actual Zeff is +3.3)

Trends for Zeff (Z-S) (Z protons - S shielding factor)

Increases Left to Right across the row and small increase Top to Bottom

Number of core e- (s) stays the same but the p+ (Z) increases, Z-S is the same down a group but larger electron cores don’t shield as well

Atomic Radius (Size) is what

Distance from Center of the nucleus to the outermost VE in an atom

Trends in Atomic Radius

Increases Right —> Left, Increases Top—> Bottom

Trend in Atomic Radius for Cations:

Cations: remove electrons +, always smaller compared to parent atom

Cation + Atomic Radius Example: Ca²⁺<Ca means what

removed e^- = making them a smaller size, removing VE means remain one’s are closer to the nucleus

Trend in Atomic Radius for Anions:

^- adds electrons, means larger than parent atom, adding VE means no extra protons to attract them means they drift farther away

Anion + Atomic Radius Example:

Cl^- > Cl the electrons mean no extra protons to attract and means they drift away

What is isoelectronic

same number of electrons series, ion that is largest so

What is Metallic Character

Metals tend to lose electrons

• easy to oxidize

• form (+) ion

• react with O₂ to form basic oxides

• React with H₂O to form hydrogen gas and heat

Metallic character reaction H2O to form hydrogen gas and heat is what reaction

exothermic 2Na (S) +2H2O —> 2NaOH + delta H<O exothermic

Trends in Metallic Character

Increases from Right to Left (hold on VE gets weaker), Increases Bottom to Top ( atomic radius decreases so VE is closer to the nucleus and bound more tightly)

Ionization Energy (IE) is what

Energy required to remove an e^- from a gaseous ground state atom or ion

Trends in Ionization

Increases Left to Right( Zeff increases so VE is bounded more tightly), Increases Bottom to Top( Atomic radius decreases so VE is closer to the nucleus and bound tighter )

Example of Ionization

E (g) —> E^+_(g)+ e^- (IE)

What are the exceptions in Ionization

Be>B and N>O it is easier to remove 2nd ionization instead of first

What is done for 2nd ionizaiton

2nd ionization energy are much larger to remove than the 1st and it takes a LOT more energy to remove core electrons

Electron Affinity (EA) is what

the affinity/willingness of a gaseous ground-state or ion to add e^- and adding an e- usually releases energy so EA one are usually negative

example of electron Affinity

E(g)+ E^- —> E ^-

Trends in electron affinity

Increase Left to right, electron values are more negative, further right more likely to fill an energy shell

Exceptions in Electron Affinity

• Nobel gasses have postive EA ( hard to add e- when already full s and p shell)

• Group 2 (Be, mg) have more positive EA, harder to add e- to a full s-subshell

• Group 5 (N,P) have more positive EA, harder to add e- to a half full p subshell

what is electron negativity

a measure of how strongly an atom attracts electrons when it's bonded to another atom

Trends in electron negativity

Increases Left to Right, and Increases from Bottom to Top