Notes: Reactivity

Energy Levels - - - - - - - - - - - - - - - - - - - - - - - - - - - - Comments: don’t talk about the 4th energy level and why it only has 8 valence electrons. It’s too confusing. Have students draw argon and helium into their notes - - - - - - - - - - - -

Valence electrons Valence electrons are electrons in the atom’s last energy level Valence electrons are used in chemical bonds. Color valence electrons in picture. They can even write the number into their notes. Last slide before cards.

What is a group/family? A column in the periodic table. The elements in a family have similar properties.

What do all elements in a group have in common? The number of valence electrons Valence electrons are electrons in the atom’s last energy level

Notice each column has the same number of valence electrons 8 is the Maximum, which what the inert gases have.

How are valence electrons used? Valence electrons are what connect atoms together to form molecules. All atoms want their energy levels filled.

Reactivity Reactivity describes how much an atom wants to create a bond with other atoms.

Chemical bond A chemical bond is a connection between atoms through their electrons. H2 O2 Show model of hydrogens boding

˜ O ˜ ˜ H H ˜ ˜ ˜ Talk about sharing electrons and covalent bonding

How many valence electrons does oxygen now have? ˜ O ˜ ˜ H H ˜ ˜ How many valence electrons does oxygen now have? ˜

High reactivity The closer they are having the maximum valence electrons the more they want to bond. One away= very reactive Na

˜ Na Cl ˜ ˜ ˜ ˜ Talk about moving electrons and ionic bonding +1 −1

˜ Na Cl ˜ ˜ ˜ ˜ +1 −1

Maximum electrons = NOT reactive What makes inert gases special? Maximum electrons = NOT reactive He Ne

Which groups are the most reactive?

To Summarize: A family/group is a vertical column. All the elements in a group have the same number of valence electrons. Valence electrons are used when atoms bond together. Valence electrons determine reactivity. Inert gases have no reactivity.