Successive IE, EA and EN

When another mole of electron is removed from one mole of gaseous ions, this is referred to as Successive Ionization Energies.

Successive Ionization Energies can be measured by bombarding the electrons into gaseous atoms.

$Ca(g)\rightarrow Ca^+(g) + e^- \therefore IE_1 = +590 kJ mol^{-1}$

This means that Ionization energies are always positive ( Endothermic ); We need to excite the atom so that the valence electron goes to the contium energy level which thus means separation from the atom. More on this on AR, IR, IE.

Trends

• It should be a given that as we continue to remove Electrons, the IE becomes higher & higher $\because$the distance from the nucleus is proportional to the attraction.

• going through the different Energy Levels, there should be jumps. For instance a 2p electron will need much more energy than a 3s electron.

Electron Affinity ( EA )

• Exothermic

• Opposite of Ionization Energy ( Gives an electron rather than take )

• The EA of an atom is the Energy Change ( $E_{ea}$), that happens when 1 mol of electron is added to 1 mol of gaseous atoms.

  • AS name entails, how easy electron be attracted

• BY convention, negative signs show a release of energy, as electrons are negatively charges

• Metals usually have a low chance to gain an electron as their tendency is to lose an electron and become a Cation; The metal nuclei do not have a strong pull on their valence electrons. $\therefore$ known to have less electron affinities.

• Nonmetals usually have higher electron affinity $\because$ of atomic structure: Usually have more valence electrons $\rightarrow$ easier for nonmetals to gain electrons to form a shell ( More Valence Electrons ) . They are usually closer to the nucleus, being it is harder to remove the electrons but easier to attract them.

• $\therefore$ $EA \propto Z_{eff}$

• $\therefore EA \propto \frac{1}{n}$

Electron Negativity( EN )

• Relative attraction an atom has on a paired electron in a covalent bond with another atom.

• Data booklet, Section 9. Uses the Pauling Electronegativity scale, $X_p$.

• Across a period $\because Z_{eff}$increases & $AR$ decreases, the attraction increases,

$\therefore$ the Electron Negativity increases

• Down a group although $Z_{eff}$ increases its increased pull is shielded by the core electrons, and a long with the increased Atomic Radius ( More levels ) --> $EN$decreases

Metallic

• Tendency to show Metallic Properties

  • Metals are more inclined to form cations and less likely to form Anions

  • Non-metals are more inclined to form Anions and less likely to form cations.

  • explained in detail above.