Ionic Bonding Notes

Chemical Bonds 1. What is a chemical bond? A force that holds two atoms together 2. What is an ionic bond? An ionic bond is the attraction between oppositely charged atoms, called ions

Review page! 3. The outermost or valence electrons of atoms are the ones involved in the formation of bonds 4. Atoms form bonds to achieve the stable electron configuration of a noble gas, typically an octet of electrons.

Example 5. Write the electron configuration of an atom of Calcium.

Example The configuration you wrote is for the neutral atom: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 How many valence electrons does Ca have? (Circle them) 6. Name three other elements that have the same number of valence electrons.

Ions 7. What charge will the ion have that is formed by calcium, and the other elements in Group 2?

New Definitions 8. Cation - positively charged ion formed when an atom loses one or more electrons 9. Anion- negatively charged ion formed when an atom gain one or more electrons Think of the “t” in cation as representing the + sign. Ca+ion

Cations and Anions 10. Do metals form cations or anions? 11. Do non-metals form cations or anions?

Practice problems 12. What ions are formed by the following elements? SAl GaN ClZn NaBe PI

Ionic Bonding Sodium, in Group 1, has one valence electron. It “wants” to lose that one electron, but the electron has to go somewhere – it doesn’t just disappear into thin air. Chlorine, in Group 17, “wants” an extra electron. Sounds like a perfect match!

Ionic Bonding 13. Convert this diagram to Lewis dot diagrams, and show how sodium transfers an electron to chlorine: Sodium Chlorine

Ionic Bonding After the electron is transferred, we have a positive sodium ion and a negative chlorine ion. Na+ Cl-

Ionic Bonding 14. What do we know about the behavior of oppositely charged particles? Na+ Cl-

Ionic Bonding Opposites attract – and that attraction is the ionic bond. Na+ Cl-

Let’s look at the bond forming…

Back to the beginning… 1. What is a chemical bond? A force that holds two atoms together 2. What is an ionic bond? An ionic bond is the attraction between oppositely charged atoms, called ions

One last point… The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I. When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day - common table salt!element compound

Last question: 15. Are the properties of a compound similar to, or different from the elements that make up the compound?

Last definition: 16. Compound: two or more atoms of different elements chemically bonded together, with different chemical and physical properties from the properties of the elements that made it.