1. Day 29 – Daily Starter What can you recall about valence electrons?
Hint: it was in your notes a while back…

2. Day 29
Chemical Bonds

3. a QUICK review…

4. Valence electrons The electrons on the outer-most orbital
Valence electrons of one atom combine with valence electrons of other atom(s) to form chemical bonds.
The number of valence electrons of an element is determined by its periodic table group (vertical column)

5. Periodic Trends Group # = # of valence e- (except He)
Families have similar reactivity.
Period # = # of energy levels 1A 2A
3A 4A 5A 6A 7A 8A

6. Valence electrons
Are represented by dots placed around the element symbol
Are the electrons that participate in chemical bonds

7. Chemical Bonds I. Why Atoms Combine Chemical Formula Chemical Bond
Stability

8. H2O A. Chemical Formula Shows: 1 oxygen atom 2 hydrogen atoms
1) elements in the compound
2) ratio of their atoms
H2O
1 oxygen atom
2 hydrogen atoms

9. Electrons
Recall that the number of protons in the nucleus of an atom (atomic #) determines the element
The number of electrons determines the element’s chemical behavior

10. B. Chemical Bond
Strong attractive force between atoms or ions in a molecule or compound.
Formed by:
transferring e- (losing or gaining)
sharing e-

11. Ne Stability Octet Rule
most atoms form bonds in order to have 8 valence e-
full outer energy level
It’s the goal of every atom!!
like the Noble Gases! Ne
Stability is the driving force behind bond formation!

12. Noble Gases…are stable!
Called Noble Gases because they are stable, and have very little or no reactivity
Why?
They have their outer shells filled
(the goal of every atom)
8th group on Periodic Table

13. 8th group of Periodic Table

14. C. Stability
Transferring e-
Sharing e-

15. Lewis Electron Dot Symbol Practice

16. (write out a full sentence on your marker board)
Do You Sense a Pattern?
How might you express this pattern, or relationship between the # of valence e- and the group #?
(write out a full sentence on your marker board)