1. Electrons Valence Electrons Bohr Models Lewis Dot Structures

2. Valence Electrons ► The electrons in the outer most electron shell are called valence electrons ► The number of valence electrons is the same as the group number 12 34567 8

3. Valence Electrons ► Valence electrons are the electrons that are available for reactions with other elements. ► Octet Rule - For atoms to “be happy” they must gain, lose or share electrons until they have 8 valence electrons  This is why atoms bond – to be happy! ► An element with a full valence shell is a happy element ► An element with a full valence shell is a happy element  Noble gases are usually unreactive ► This is because they have full valence shells

4. 4 Becoming An Ion ► Electrons are negatively charged ► Protons are positively charged ► Neutral atoms do not have a charge because the number of protons is the same as the number of electrons ► When atoms gain or lose electrons (to become happy) they become positively or negatively charged ► An atom with a charge is called an Ion

5. Common Charges of Ions +1+2 +3±4-3-2 0

6. Bohr Models ► Niels Bohr created a visual model of the atom to make them easy to understand ► A Bohr Model contains a central nucleus surrounded by electron shells ► For each model you state the element in the nucleus and draw a dot on the electron shells for each electron

8. Lewis Dot Structures ► electron-dot structure – consists of element’s symbol surrounded by dots that represent the atom’s valence e –