Warm Up 1/7 - Protons, Neutrons, Electrons 5 B Boron 11 11 Na Sodium 22 17 Cl Chlorine 35 2 He Helium 4 a. For each element: How many Protons? Electrons? Neutrons? b. For each element: Draw a Bohr Model

Remember the rules for Bohr Models Inner shell – 2 Electrons Middle shell – up to 8 electrons Outer shell – up to 8 electrons

Valence Electrons Valence electrons are the electrons in the outside electron shell of an atom. Valence electrons are important in how a element reacts with other elements. Elements which have eight valence electrons (noble gases) are inert and they do not tend to create chemical reactions with other elements. The number of valence electrons determines how an atom reacts with other atoms.

Nobel Gasses Have 8 Valance Electrons Nobel Gasses do not react, or form bonds, with other elements.

The Octet Rule The octet rule that states that atoms tend to combine in such a way that each atom has eight electrons in its outer (valence) shell, giving it the same stable electron configuration as a noble gas.

. What atoms make up a molecule of water? H2O

Draw a Bohr model of Hydrogen and A Bohr model of Oxygen The number of valence electrons determines how atoms react with other atoms. Draw a Bohr model of Hydrogen and A Bohr model of Oxygen 1 H Hydrogen 8 o Oxygen 16

The number of valence electrons determines how atoms react with other atoms. Try this! Draw three Bohr models showing how one oxygen atom forms bonds with two hydrogen atoms. Hint: Atoms can share electrons! Have students draw their model on the board

Notice the valence electrons A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.

Electrolysis of Water Running an electrical current through water can separate the hydrogen and oxygen atoms.

How will we know we separated the hydrogen and oxygen of the water molecule? Remember the Hindenburg?

Lab Materials & Set Up Video