Trends in the Periodic Table - PowerPoint PPT Presentation

Loading...

PPT – Trends in the Periodic Table PowerPoint presentation | free to download - id: 17cfa-MzQyZ



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Trends in the Periodic Table

Description:

Trends in the. Periodic Table. Atomic radius. The best measure of atomic radius is the bond radius. ... Measure the distance between the nuclei of 2 atoms ... – PowerPoint PPT presentation

Number of Views:63
Avg rating:3.0/5.0
Slides: 13
Provided by: rochiol
Category:
Tags: periodic | table | trends

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Trends in the Periodic Table


1
Trends in the Periodic Table
2
Atomic radius
  • The best measure of atomic radius is the bond
    radius. Measure the distance between the nuclei
    of 2 atoms bonded together and divide by two.

3
  • Going down a group, the atomic radius increases.
  • Larger atoms have more electrons farther away
    from the nucleus.
  • The inner electrons shield the outer electrons
    from the full effect of the positive charge of
    the nucleus.

4
  • Going across a period, the atomic radius
    decreases
  • Electrons are being added to the same principal
    energy level.
  • For every added electron, a proton is also being
    added to the nucleus, increasing the charge,
    pulling the electrons tighter in.
  • This change is not as noticeable with heavier
    elements (inner electrons shield).

5
(No Transcript)
6
Ionization Energy
  • The energy required to remove an electron from an
    atom in the gas phase
  • There is a series of ionization energies for each
    electron removed. These energies get higher for
    each subsequent electron.
  • The trends given are for the first electron
    removed.

7
  • Going down a group, the ionization energy
    decreases.
  • Electrons are further out, so the nuclear charge
    is not felt as strongly.
  • Shielding effect contributes.

8
  • Going across a period, the ionization energy
    increases.
  • For every added electron, a proton is also being
    added to the nucleus, increasing the charge.
  • The same principal energy level is being filled,
    so the shielding effect is a constant.
  • There are some exceptions to this trend, normally
    in cases of full or half-full energy sublevels.

9
(No Transcript)
10
Electron Affinity
  • Measures how much an atom wants to gain
    electrons
  • Is the change in energy associated with gaining
    an electron
  • High electron affinity really wants to gain an
    electron- rE is a negative number with a high
    absolute value
  • e.g. F rE -328.5 kJ/mole
  • Low electron affinity doesnt want to gain an
    electron
  • e.g. Noble gases have positive values of rE

11
  • Going down a group, the electron affinity
    decreses
  • Shielding more than offsets the increase in
    nuclear charge
  • Going across a period, the electron affinity
    increases (rE becomes more negative).
  • Shielding remains constant, the nuclear charge
    increases
  • EXCEPTION The noble gases have the lowest
    electron affinities of all.

12
(No Transcript)
About PowerShow.com