1. Chemical Bonding

2. Bellwork
When a nail rusts, is that a chemical change or a physical change? Explain.

3. Objectives Students should be able to
Distinguish between ionic and covalent bonds
Identify when elements will form ionic or covalent bonds
Distinguish between compounds and molecules

4. Chemical Bonding Compounds Two types of chemical bonds
atoms of two or more elements
joined together by chemical bonds
Two types of chemical bonds
Ionic Bonds-
one atom transfers an electron to another atom
Covalent Bonds-
two atoms share electrons

5. Ionic Bonding transfer of electrons
Why?
Each atom becomes more stable (full outer shell)
Atom that loses an electron
have only 1 or 2 valence electrons
Atom that gains an electron
have 7 electrons in valence shell
Ions
Atoms that gain or lose electrons
Ex. NaCl

6. Covalent Bonding share electrons
Why?
Atoms share electrons to become stable
to fill their outer shells
The number of bonds that form
equals the # of electrons needed to fill outer shell Ex. H2, O2, N2

7. Chemical Bonding

8. Notetaker Practice
Use a Venn Diagram to compare and contrast ionic bonds and covalent bonds.

9. Notetaker Practice
Examples we work together: How many covalent bonds are formed in H2? In N2?
Now your try it: How many covalent bonds are formed between oxygen atoms in O2?

10. Molecule
Molecule
two or more atoms joined by covalent bonds
How is a molecule different than a compound? Write answer on your notetaker.
Can NaCl be a molecule? Explain why or why not on your notetaker.

11. Notetaker Practice
Explain the difference between a compound and a molecule

12. Chemical Reaction Process where Ex. 2H2 + O2  H2O
atoms rearrange and form new bonds
Ex. 2H2 + O2  H2O
different from a physical change

13. Chemical Change vs Physical Change
Examples
Rust on a Chain : O2 + Fe  Fe2O3
chemical reaction because bonds break and
re-form
Boiling Water : H2O(liq) + heat  H2O(gas)
not a chemical reaction, no rearranged bonds
physical change

14. Thumbs up Chemical Change / Thumbs down Physical Change?
Thumbs up Chemical Change / Thumbs down Physical Change
You Cut the Grass You combust gasoline in your car You digest the protein in your hamburger You dissolve sugar in water You dissolve Alka-Seltzer in water
1. Hand signals:
thumbs up or thumbs down to indicate agreement or disagreement
use fingers to indicate a number selection such as “Which is the correct solution one, two or three?”
teacher gives feedback to the students 14 14

15. Notetaker Practice
Explain, in your own words, what happens during a chemical reaction.