CHEMICAL BONDING

CHEMICAL CHANGE

• AKA Chemical Reaction

• Occurs when chemical bonds are destroyed and new bonds made.

• The number of electrons in an atom can be determined from the atomic number of the element.

Remember?

Electron Number and Organization

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 ELECTRONS =

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