1. Ionic Bonds LEARNING TARGET: HOW DOES AN ION BECOME POSITIVELY OR NEGATIVELY CHARGED? HOW DOES AN IONIC BOND FORM?

2. ions What is an ion?  When an atom loses or gains a valence electron, it becomes an ion.  An ion is an atom that is no longer neutral because it has gained or lost an electron.

3. Ions  An atom that loses a valence electron becomes a positively charged ion (+). (BECAUSE IT NOW HAS MORE PROTONS THAN ELECTRONS)  An atom that gains an electron becomes a negatively charged ion (-). (BECAUSE IT NOW HAS MORE ELECTRONS THAN PROTONS)  Metal atoms are more likely to lose electrons and nonmetals are likely to gain electrons  Opposite charged particles attract

4. Let’s Experiment:  Let’s investigate solutions to determine if they contain ions.  Solutions that contain ions when dissolved in water will conduct electricity.

5. Ionic Compounds  Ionic compounds are usually not conductors of electric current because ions in solid form are tightly formed and can not move.  However, when dissolved in water, the ions are free to move about and can conduct an electric current.  Therefore solutions containing ions can conduct electricity.

6. Let’s Explore this further! Example of Ion Formation  Let’s explore the element Sodium – Na located in Group 1 on the Periodic Table  Its atomic number is 11; so how many protons does it have? Why?  How many electrons does it have? Why?  If Sodium loses an electron, how many electrons does it have?

7. Ions and Ionic Bonds  Since Sodium lost an electron, it is no longer a neutral atom. It has become an ion.  Sodium (Na) now has 1 more proton (11) than electrons (10), so its charge is positive Na + and is considered a positively charged ion.  Now with 8 electrons in its outer energy level it is stable.

8. Example of ion formation  Nitrogen (N)  Atomic # = 7, # of protons = ___  How many electrons does (N) have?____  What does it need to become stable?____  7 +3 electrons =10, 7 protons -10 electrons = -3. Nitrogen has a -3 charge. N 3 -

9. Ionic Bonds  Ionic bonds – when atoms that easily lose electrons react with atoms that easily gain electrons, valence electrons are transferred from one type of atom to another. This transfer gives each atom a more stable arrangement of electrons.  Ionic bonds form when valence electrons move from a metal to a nonmetal

10. Ionic Bond to Ionic Compound  Sodium atom (Na) has 1 valence electron and Chlorine (Cl) atom has 7 valence electrons.  The valence electron on Na is transferred to the Cl. Both atoms become ions. The sodium is Na+ and the chlorine is Cl-.  Opposite charged particles attract and an ionic bond is formed.  The resulting compound is called an ionic compound

12. Ionic Bonding Rules  When 2 elements join together using ionic bonding, one element gives away 1 or more electron to the other one.  Both elements must try to get a full outer energy level by getting or giving away an electron  One element becomes positive and the other becomes negative  Opposite particles attract to form an ionic compound