Chapter 7 Ionic and Metallic Bonding Mr. Samaniego Lawndale High School

Section 7.1 - Ions When Mendeleev arranged his periodic table according to properties, he didn’t know that it was also due to the number of bonding electrons The reason that certain elements were grouped together was because they have the same number of valence electrons Valence Electrons – electrons in the highest occupied energy level of an atom To find the valence electrons in an atom of the representative element, simply look at the group number

He 2 e-

Determine the Valence electrons in each of these elements K 6. Be P 7. Li C 8. He O 9. Ne N 10. B

Electron Dot Structure A diagram that shows valence electrons as dots around the element symbol PRACTICE 1. K 6. Be 2. P 7. Li 3. C 8. He 4. O 9. Ne 5. N 10. B

Valence Electrons The reason that valence electrons are so important is that they are the only electrons involved in bonding

Octet Rule Remember that all atoms want to be like the noble gases because their s and p orbitals are completely filled, which makes them unreactive and stable The Octet Rule states that all atoms want 8 electrons in their valence shells, just like the noble gases (except He)

Satisfying the Octet Rule In forming compounds, atoms want to achieve a noble gas configuration In order for atoms to combine together to obtain 8 valence electrons, they transfer electrons (either gain or lose electrons)

Some atoms will gain electrons, while other atoms will lose electrons Filling Order: 1s 2s 2p 3s 3p 4s 3d 4p Draw the orbital diagram for Sodium Draw the orbital diagram for Magnesium Draw the orbital diagram for Fluorine Draw the orbital diagram for Oxygen

Cation versus Anion Remember that atoms are electrically neutral because they have the same number of protons and electrons

How are electrons transferred? Metals lose valence electrons Nonmetals gain valence electrons

Bonding Once an atom has a stable octet, it is happy and does not want to react anymore Atoms without stable octets are sad and want to react with other atoms to achieve a stable octet Why don’t noble gases want to form bonds?

How do atoms become more stable and less reactive? Why do atoms form bonds? 1. To have a full octet 2. To be more stable 3. To be less reactive How do atoms become more stable and less reactive? By having completely filled s and p orbitals just like the noble gases

Charges on the Periodic Table

Practice What are the charges on the following elements? Calcium Oxygen Chlorine Hydrogen Cesium Helium Krypton Aluminum

Section 7.2 – Ionic Bonds Ionic Compounds are METAL cations and NONMETAL anions held together by electrostatic forces Ionic compounds are formed through transferring or exchanging electrons

Example… Sodium Chloride (Salt, NaCl) is an example of an ionic compound

Practice Which of the following are ionic compounds? LiCl NaS C2H4 MgBr2 H2O SiC Rb3P CsI

Ionic Charges Although they are composed of positive and negative charges, ionic compounds are overall electrically neutral because their charges will cancel out For example… Na+1 will bond with Cl-1 Mg2+ will bond with O2- Al3+ will bond with N3- Two K+1 can also bond with One S2-

Writing Chemical Formulas Al2S3 The numbers on top are the charges, while the numbers on the bottom tell how many atoms there are

Practice Li+1 Ca2+ Al3+ N3- S2- Cl-1 Write as many compounds as you can with the following ions. Remember that the overall charge must be zero. There are 9 possible. Li+1 Ca2+ Al3+ N3- S2- Cl-1

Salt Salt crystals are repeating patterns of positive and negative ions held together by electrostatic attraction

Ionic Bonding When cations and anions transfer electrons, a SALT is formed Draw the electron dot structure for the following atoms Li and Br Mg and O Two K and One S One Sr and Two F

SALTS When cations and anions form bonds with each other they are called SALTS Example: Li 1s 2p F Li+ LiF F-

Practice Show how the following compounds bond with the use of orbital diagrams NaF MgO Li2S CaCl2 AlN

Properties of Ionic Compounds Crystalline Solid at Room Temperature High Melting Points Can conduct an electric current when melted or dissolved in water

Section 7.3 – Bonding in Metals Metal atoms are arranged in very compact and orderly patterns

Metallic Bond A Metallic Bond is a bond between metal cations surrounded by a sea of electrons

Metallic Bond The attraction of the free floating valence electrons holds them together

Crystalline Structure of Metals (Page 202)

Properties of Metals Good Conductors of electrical current 2. Ductile (ability to be stretched) 3. Malleable (ability to be shaped)

Alloys Very few of the metal objects you use everyday are pure metals Alloys are a mixture of two or more elements, at least one being a metal Alloys are important because the combination of metals are stronger than the single metal by itself

Examples of Alloy Combinations Brass – copper and zinc Sterling Silver – silver and copper Bronze – copper and tin Steel – iron, carbon, boron, chromium, manganese, molybdenum, nickel, tungsten, vanadium Stainless Steel – iron, chromium, carbon, nickel Cast Iron – iron and carbon

Homework Chapter 7 Assessment