Skip this Video
Download Presentation
Ionization Energy Trends

Loading in 2 Seconds...

play fullscreen
1 / 27

Ionization Energy Trends - PowerPoint PPT Presentation

  • Uploaded on

4f. 5f. Ionization Energy Trends. Electronegativity. Increasing Electronegativity. Decreasing Electronegativity. Lewis Structure Assumptions. Only valance electrons are involved in bonding. Atoms react to form molecules, so to achieve stable noble gas electron configurations.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Ionization Energy Trends' - kamran

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript



Increasing Electronegativity

Decreasing Electronegativity

lewis structure assumptions
Lewis Structure Assumptions
  • Only valance electrons are involved in bonding.
  • Atoms react to form molecules, so to achieve stable noble gas electron configurations.
  • Atoms in molecules want eight valance electrons (octet rule) except for hydrogen which wants two electrons (duet rule).
  • In covalent compounds atoms share electrons to form bonds in order to achieve stable noble gas electron configurations. In ionic compounds electrons are transferred from one atom to another to achieve stable noble gas electron configurations.
rules for drawing lewis structures
Rules for Drawing Lewis Structures

Step 1: Count the total number of valance electrons.

Step 2: Identify the central atom (the first atom written unless that atom

is hydrogen). Place all terminal atoms around that atom.

Hydrogen atoms NEVER have more than one bond.

Step 3: Complete the octet for all atoms in the Lewis structure with

lone pairs of electrons (except hydrogen).

Step 4: Check your structure by counting the number of valance

electrons used (they will match step 1 if the structure is

correct). If your valance electrons don’t match you will need

to tweak your structure as follows.

tweaking lewis structures
Tweaking Lewis Structures

Too Many Electrons Initially: Redraw the

Lewis structure from step 2 adding a double

bond. If you still have too many electrons

add another multiple bond and repeat.

Always add double bonds before triple

bonds. Every double bonds effectively

remove two electrons from the structure while

triple bonds effectively remove 4 electrons.

exceptions to the octect
“Exceptions” to the Octect

Two Few Electrons: If you only have four or

six valance electrons initially you can’t

possibly fill the octet rule (usually BeH2 or

BH3). Just place hydrogens around central

atoms and call it done.

exceptions to the octect1
“Exceptions” to the Octect

Odd number of electrons: One atom will

have to have less than eight electrons.

Draw the Lewis structure as if it had one

more valance electrons than it actually does.

Then subtract one electron from the least

electronegative element (often the central


exceptions to the octect2
“Exceptions” to the Octect

Exceeding the Octet Rule: If the central atom is in

the third row or below it may be possible to exceed

eight electrons around the central atom. But only if

you absolutely have no choice. If you can give

everything eight and only eight do that first. When

you must break the octet rule draw the structure as

you would in steps 1-4 and the place the extra

electrons around the central atom. Even when

breaking the octet rule no atom will ever have

more than 12 electrons.

organic lewis structure rules
Organic Lewis Structure Rules
  • Based on formal charge arguments