Active Chemistry

1
Active Chemistry
Periodic Table Activity 8-9
2
Lewis Dot Structures

• Lewis dot structures are shorthand to represent
  the valence electrons of an atom.
• The structures are written as the element symbol
  surrounded by dots that represent the valence
  electrons.

3
Practice

• Draw the Lewis structure for the following
• H
• Mg
• B
• Si
• P
• O
• Cl
• (What do you notice?)

4
Octet Rule

• All atoms want to get 8 electrons in their outer
  shell (Valence electrons

I want to be a noble gas!!
8 electrons in the outer shell!!
5
Types of Bonds

• Ionic electrons are transferred
• Metals lose Nonmetals gain

• Covalent- electrons are shared

Lets just share these electrons!
You can have my electrons.
Thanks dude!
http//www.youtube.com/watch?vQqjcCvzWwwwNR1
http//www.youtube.com/watch?vyjge1WdCFPsNR1
6
Ionic Compounds and bonding
The oppositely charged ions are attracted to each
other by electrostatic forces, which are the
basis of the ionic bond.
http//www.youtube.com/watch?vxTx_DWboEVs
7
Anions Vs. Cations

• Anion negative charge (-) caused by gaining
  electrons.
• Nonmetals (groups 15, 16, 17/ right of
  staircase)

• Cations positive charges () caused by losing
  electrons
• Metals (groups 1 13/ left of staircase)

8
What happens when positive charges and negative
charges come together??

• THEY ATTRACT

http//www.youtube.com/watch?vERy18NwemVc
9
Finding a match
10
Review -Chemical Bonds

• There are 2 forms of bonding
• _________complete transfer of 1 or more
  electrons from one atom to another (one loses,
  the other gains) forming oppositely charged ions
  that attract one another
• _________some valence electrons shared between
  atoms

Most bonds are somewhere in between ionic and
covalent.
11
Building a Dot Structure

• Hydrogen - H2
• 1. How many valence electrons? (1)
• 2. Add up the number of valence electrons that
  can be used.
• H 1 and H 1
• Total (1 1) 2
• 2 electrons
• 3. Put dots together
• With dots- HH

Electrons
12
Building a Dot Structure

• Hydrogen - H2
• With dots- HH
• 4. When two dots are together,
• replace with a line.
• HH H-H

Electrons
13
Covalent Bonding

• The H2 molecule is a good example because both
  atoms in the H2 molecule have an equal attraction
  (or affinity) for electrons

14
Building a Dot Structure

• Ammonia, NH3
• Number of Valence electrons
• H 1 N5
• Decide on the central atom never H.
• 2. Add up the number of valence electrons that
  can be used.
• H 1 and N 5
• Total (3 x 1) 5
• 8 electrons / 4 pairs

15
Building a Dot Structure

• 3. Form a single bond between the central atom
  and each surrounding atom (each bond takes 2
  electrons!)

4. Remaining electrons form LONE PAIRS to
complete the octet as needed (or duet in the case
of H).
3 BOND PAIRS and 1 LONE PAIR.
16
Building a Dot Structure

• Check to make sure there are 8 electrons around
  each atom except H. H should only have 2
  electrons. This includes SHARED pairs.

6. Also, check the number of electrons in your
drawing with the number of electrons from step 2.
If you have more electrons in the drawing than
in step 2, you must make double or triple bonds.
If you have less electrons in the drawing than in
step 2, you made a mistake!
17
Practice

• If X represents an alkali metal (group 1A), what
  is the formula for a compound formed by X and
  oxygen? Hint think of water.
• Draw the Bohr model of sodium. How will sodium
  act if it is forming an ionic bond?