1 / 8

Electron affinity cont.

Electron affinity cont. As e- add to the same p sublevel of atoms with increasing nuclear charge. E- affinities become more negative across each period within the p block. Exception between groups 14 and 15

lassie
Télécharger la présentation

Electron affinity cont.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Electron affinity cont. • As e- add to the same p sublevel of atoms with increasing nuclear charge. • E- affinities become more negative across each period within the p block. • Exception between groups 14 and 15 • Adding an e- to a carbon atom gives a half-filled p sublevel, this occurs more easily than forcing an e- to pair with another e- in an orbital of the already half-filled

  2. Group trends • E- add with greater difficulty down a group. • Because of an increase in effective nuclear charge down a group, which increases e- affinity. • Increase in atomic radius down a group, decreases e- affinities. • Exception – heavy transition metals, tend to be the same size or even decrease in radius down a group.

  3. Adding e- to negative ions • For an isolate ion in the gas phase, it is always more difficult to add a second e- to an already negatively charged ion. • Second e- affinities are all positive. • Certain p-block nonmetals tend to form negative ions that have noble gas configurations. • With halogens it is difficult to add another e- because they have noble gas configuration after becoming a negative one ion.

  4. Ionic radii • Cation – positive ion, loss of one or more electrons. – leads to decrease in atomic radius • Anion – negative ion, addition of one or more e-, leads to an increase in atomic radius. (positive charge remains the same)

  5. Period trends • Metals tend to form cations. • Nonmetals at the upper right tend to form anions. • Cationic radii decrease across a period because the e- cloud shrinks due to the increasing nuclear charge acting on the e-. • Anionic radii decrease across each period for the elements in groups 15-18. (same reason why cation radius decrease)

  6. Valence electrons • Electrons available to be lost, gained, or shared in the formation of chemical compounds. • Usually located in incompletely filled main-energy levels. • What sublevel are the valence e- located? • Group 1 and 2 • Transition elements • Group 13-18

  7. electronegativity • Linus Pauling devised a scale of numerical values reflecting the tendency of an atom to attract electrons. • Electronegativity – measure of the ability of an atom in a chemical compound to attract e- from another atom in the compound. • Most electronegative element is Flourine • Why not At?

  8. Period trends • Electronegativities tend to increase across each period • alkali and alkaline-earth metals are the least electronegative.

More Related