Chapter 7 Atoms and Bonding

Section 1 What is a Chemical Bond?

Chemical Bonding The combining of elements to form new substances. The rules of chemical bonding are determined by the structure of the atom.

Electrons and Energy Levels The electrons in the outermost energy level are called Valence electrons Atoms that have full outer energy levels of electrons do not usually form chemical bonds Atoms whose outer energy level is not full of electrons do usually form chemical bonds

Electrons and Bonding The electron arrangement of the outermost energy level of an atom determines whether or not the atom will form chemical bonds. Atoms with full outer energy levels tend not to form bonds Atoms whose energy levels are not full tend to gain or lose electrons in order to fill its outermost energy level.

Electrons and Bonding Li F

Electrons and Bonding F Li

Electrons and Bonding F Li

Electrons and Bonding F Li

Electrons and Bonding Li F

Electrons and Bonding F Li Lithium lost 1 electron Fluorine gained 1 electron Full outer energy level ****Stable****

Electrons and Bonding In order to achieve stability, an atom will either gain or lose electrons. In other words an atom will bond with another atom if the bonding gives both atoms complete outermost energy levels.

Electron Dot Diagrams Used for shorthand way of showing chemical bonding

Lewis Dot Diagrams Rules: Write the symbol of the element Place only the valence electrons around the symbol. Pair electrons only after placing single electrons around the symbol first.

Lewis Dot Diagrams HeliumLithium CalciumBromine

Lewis Dot Diagrams When showing chemically bonded atoms: Use X’s for one atom’s electrons and dots for the other atom’s electrons