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

Day 29 Chemical Bonds

a QUICK review…

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)

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

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

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

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

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

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

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!

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

8th group of Periodic Table

C. Stability Transferring e- Sharing e-

Lewis Electron Dot Symbol Practice

(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)