Bonds, Chemical Bonds Chapter 0013

Combining Atoms Through Chemical Bonding Chemical bonding is the joining of atoms to form new substances An interaction that holds two atoms together is called a chemical bond. When chemical bonds form, electrons are shared, gained, or lost.

Discussing Bonding Using Theories and Models We cannot see atoms and chemical bonds with the unaided eye. So, the use of models helps people discuss the theory of how and why atoms form bonds. and why atoms form bonds.

Electron Number and Organization # of electrons in an atom = the atomic number of the element. electrons in an atom are organized in energy levels.

Outer-Level Electrons and Bonding Most atoms form bond using only its valence electrons, the electrons in an atom’s outermost energy level.

Valence Electrons and the Periodic Table You can use the periodic table to determine the number of valence electrons for atoms of some elements, as shown on the next slide. ___________________________________________________________________

To Bond or Not to Bond The number of electrons in the outermost energy level of an atom determine whether an atom will form bonds. Atoms that have 8 electrons in their outermost energy level do not usually form bonds. The outermost energy level is considered to be full if it contains 8 electrons

Filling the Outermost Level An atom that has fewer than 8 valence electrons is more likely to form bonds than at atom that has 8 valence electrons is. Atoms bond by gaining, losing, or sharing electrons so they can fill the outermost energy level.

The Octet Rule Atoms like to be stable! They go to great lengths to be stable and happy. Stability to an atom is a complete outer energy level. The outer energy level is full of the valence electrons.  Valence electrons are the electrons in the highest occupied energy level of an atom. The number of valence electrons mostly determines the properties of an element.

The Octet Rule An octet is a set of eight think 'octopus' In chemistry, the octet rule says that atoms like to have full outer shells of only eight electrons.

Is Two Electrons a Full Set? Not all atoms need 8 valence electrons to have a filled outermost energy level. Helium atoms need only 2 valence electrons because the outermost level is the first energy level. Atoms of hydrogen and lithium form bonds by gaining, losing, or sharing electrons to achieve 2 electrons in the first energy level.

Enjoy Your Bond Adventure !