Chemical Bonds

Chapter 8

Forming chemical bonds

• The force that holds two atoms together is called a chemical bond.

• Chemical bonds form because of attractions between oppositely charged atoms called ions.

• Elements tend to react so as to achieve the stable electron configuration of a noble gas.

A cation or positive ion , is formed when an atom loses one or more electrons.

An anion, or negative ion, Is formed when an atom gains one or more electrons.

• A neutral atom of element 20 would have 20 electrons.

2 2 6 2 6 2• Electron configuration 1s 2s 2p 3s 3p 4s• To achieve the stable electron configuration of

a noble gas, the atom would tend to lose its two valence electrons, the atom would

• tend to lose its two valence electrons.

• The configuration for this ion would be • 2 2 6 2 6• 1s 2s 2p 3s 3p

• For each of the following atoms, write the electron configuration, referring to the periodic table. Then write the formula of the ion the atom is most likely to form and identify that ion as a cat ion or an anion , then write the configuration of the ion

• 1- bromin 35• 2- gallium 31• 3- sulfur 16• 4- rubidium 37

Ionic Bonds

• Ionic bond is the force that holding the oppositely charged ions together.

• The total number of electrons lost = the total number of electrons gained.

• Mg lose its tow valence electrons to form 2+ ion.• Cl gain one electron to form 1+ ion• Each Mg ion will need two Cl ions.