Friday December 4, 2015 TO DO RIGHT NOW: 1.P110- copy words of the day 2.P114-glue in reading “Chemical bonding” 3.P115- title “Types of Bonds” 3. p116- title “Using EN to determine bond type” HOMEWORK Due Monday- Polarity and EN worksheet REMINDERS Check your grades. Tutorials today until 3:00 only

Chemical Bonding Article Yellow Chemical Bonding paper Unit 6

A chemical bond is: An attraction between the nuclei and valence electrons of different atoms that holds the atoms together (the hook up!!!)

Why do atoms bond? (outer flap) Most elements (besides noble gases) are very unstable When they bond they become more stable (like a noble gas) Everybody has their 8!!! They had to share to help each other out.

How do atoms bond? atoms bond by gaining, losing, or sharing e- Most Group A elements (s and p - block) want to attain an octet (8 valence e-) Octet Rule – most elements want to have 8 valence electrons to achieve stability

Types of bonding (open flaps) 1. Ionic Bonds Transfer e - from a metal to a nonmetal Smallest ratio is called a formula unit Example  (metal) CaCl 2 (nonmetal)

Ionic Bond (draw & label this!) Notice the pair of electrons is all the over on the right. Higher electronegativity More attractive! + + Metal  nonmetal e-e- e-e- e-e- e-e-

2. Covalent sharing of e- between 2 nonmetals Smallest ratio of a covalent compound is called a molecule Examples: H 2 H 2 O & C 6 H 12 O 6

2 types of covalent bonds: (draw pics too) Nonpolar covalent Equal sharing of e - Example: H 2 Polar covalent Unequal sharing of e - Notice right is pulling harder Example: HCl + + = + +

Polar Covalent Bond electrons shared unequally Chlorine has higher electronegativity (EN) so it pulls harder HCl Hydrochloric acid

3. Metallic Bonding  All involved atoms are metals (duh!)  Electrons are shared in a “sea of free flowing or mobile electrons” by all atoms  This flow is responsible for ductility, malleability, luster and ability to conduct heat and electricity  Example: copper wire

The “sea” of electrons

2 ways to determine bond type (fold up your bottom flap) 1. Location on the periodic table metal + nonmetal = Ionic nonmetal + nonmetal = Covalent metal + metal = Metallic

2. taking the difference in the electronegativity (subtract!!!) Sulfur and Hydrogen 2.5 – 2.1 = 0.4 Nitrogen and Cesium 3.0 – 0.7 = 2.3 Chlorine and Bromine 3.0 – 2.8 = 0.2 Polar covalent Ionic Nonpolar covalent 4.0 ionic 1.7 polar cov 0.3 nonpolar cov

Why do atoms bond clip 9yHSJ29I

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