CHEMICAL BONDING

CHEMICAL CHANGE AKA Chemical Reaction Occurs when chemical bonds are destroyed and new bonds made.

Electron Number and Organization The number of electrons in an atom can be determined from the atomic number of the element. Remember? Atomic # = # of protons = # of electrons + = -

Where are the electrons? Electrons in an atom are organized in energy levels. The next slide shows a model of the arrangement of electron in an atom. This model and models like it are useful for counting electrons.

Valence Electrons Most atoms form bonds using only its valence electrons, the electrons in an atom’s outermost energy level. N TOTAL ELECTRONS = VALENCE

PERIODIC TABLE & VALENCE ELECTRONS GROUP 1 = 1 valence electron GROUP 2 = 2 valence electrons GROUP 13 = 3 valence electrons GROUP 14 = 4 valence electrons GROUP 15 = 5 valence electrons GROUP 16 = 6 valence electrons GROUP 17 = 7 valence electrons GROUP 18 = 8 valence electrons

Valence & Bonding # of Valence electrons determines bonding. Atoms that have 8 valence electrons do not usually form bonds because they are full. Atoms that have less than 8 valence electrons form bonds because they are not full

N N