Ionic and Metallic Bonding Chapter 7 Ionic and Metallic Bonding

Bonding--definition Bonding attractive forces binding ‘atoms’ or ‘ions’ together to form a cpd (ionic and covalent) attractive forces holding …… or

Compound Compound atoms of different elements join together chemically totally different in chem properties from the elements …. Elements form cpds to increase in stability Electrically neutral A + B → A-----B bond Elements cpd e.g. Na + Cl2 → NaCl

bonding Form cpds Pure metal Intermolecular forces Metallic Bond Van der waals Forces H bond Ionic bond Covalent bond Ion-dipole Dipole-dipole London dispersion

2 Types of Bonding—form cpds Ionic bonding transfer e- → cations and anions Metal + nonmetal(s) Form ionic cpds (e.g. NaCl) 2. Covalent bonding share e- (no ions) Nonmetals only; (e.g. CO2, H2O) form covalent cpds (molecular cpds)

Compounds Covalent cpds or molecular cpd Ionic cpds Covalent bonds formed by formed by Covalent bonds Ionic bonds Sharing e- Transfer of e- Metal + nonmetal(s) nonmetals e.g. MgO e.g. H2O

2 Types of Bonding— do not form cpds *3. Metallic bonding in metallic elements does not form cpds. *4. Hydrogen bonding between H and O, N, or F atoms (among molecules) does not form cpds

Valence e- Valence e- e- in the highest EL of an atoms. # valence e- largely determines the chem properties of an element.

Valence e- # of valence e- in an atom of (a representative element) = group # or the ones digit of the group #

Valence e- 7.1

The Octet Rule (1) The Octet Rule Atoms of what type of elements tend to lose e-? metals: groups 1A, 2A, 3A, B Atoms of what type of elements tend to gain e- ? Nonmetals: groups 5A, 6A, 7A

The Octet Rule (2) In forming cpds, atoms tend to achieve the e- confign of a noble gas.

Ionic Bonding Ionic bonding transfer e- Metal + nonmetal(s) Metals (1A, 2A, 3A, transition) lose e- to form …→ cations Nonmetals (5A, 6A, 7A) gained e- to form … cations and anions attract each other → Ionic cpd

Ionic Bonding Cation and anion attract each other by electrostatic force ionic cpds [metal + nonmetal(s)] e.g. Na → Na+ + e- (loss) Cl + e- → Cl- (gain) Na+ ~~ Cl- Electrostatic attraction

Formation of Ionic Cpds Formula Units (ionic cpds) the lowest whole-# ratio of ions in an ionic cpd. A chemical formula shows the kinds and #s of atoms in the smallest representative unit of a sub. e.g. NaCl is a formula unit of sodium chloride—1 Na+ bonded to 1 Cl-

The Octet Rule (3) Losing valence e- Atoms of metals tend to lose their valence e- leaving a complete octet in the next-lower EL. e .g. Na (1s22s22p63s1) loses 1 valence e ---- leave a Ne e-confign (1s22s22p6)→ Na+ Neon e- confign

The Octet Rule (4) Gaining e- Atoms of some non-metals tend to gain e- to achieve a complete octet. e.g. Cl (1s22s22p6 3s23p5 ) achieve an e- confign of Ar (Cl- 1s22s22p6 3s23p6 ) after gaining 1 e- Ar e- confign

Formation of Cations An atom lost valence e- produces a cation (+ve). e.g. Na → Na+ + e- Mg → Mg 2+ + 2 e- e.g. Al → cations

Formation of Cations cations are produced by the loss of valence e- from metal atoms. The e- loss (ionization) of the Na atom Ne e- confign

Formation of Cations The e- confign of the Na+ is the same as that of a Ne atom. Na+

Na+ and Ne Differences Similarity same e- configuration both octet Na+ charge +ve charge none # p+ 11 10

Formation of Cations 1 unit of +ve charge 1 unit of –ve charge Na ion

Formation of Cations A Mg atom attains the e- confign of Ne by losing both valence e-. The loss of valence e- produces a Mg cation (Mg2+) with a charge of 2+. (2 units of –ve charge) (2 units of +ve charge)

Formation of Cations Cations of gp 1A 1+ Cations of gp 2A elements 2+

A particle derived from an atom (nonmetals) or a group of atoms Formation of Anions The gain of e- by a neutral atom → an anion. A particle derived from an atom (nonmetals) or a group of atoms Carries -ve charge(s) after gaining e-. many names of an anion ends in -ide. e.g. oxide, chloride, fluoride, sulfide, nitride, iodide,

Formation of Anions H H- N N3- P P3- O O2- S S2- F F- Cl Cl- Br Br- I

Formation of Anions A gain of 1 e- gives Cl an octet and converts a Cl atom into a chloride ion (Cl-). the same e- confign as the noble gas Ar.

Formation of Anions Both a Cl- and the Ar atom have an octet of e- in their highest occupied ELs.

Formation of Anions In this eqn, each dot in the e- dot structure represents an e- in the valence shell in the e- confign diagram. 7 valence e- Octet

Formation of Anions halide ions ions produced when atoms of Cl and other halogens gain e-. Fluorides (F-), chlorides, bromides, iodide All halogen atoms need to gain only 1 e- to achieve the e- confign of a noble gas.

Formation of Anions O is in Gp 6A.

Ionic Charges of Some Ions 1+ 2+ 3+ 3- 2- 1- H+ H- Li+ Be2+ N3- O2- F- Na+ Mg2+ Al 3+ P 3- S2- Cl- K+ Ca2+ Br- Ag+ Ba2+ I- Fe 2+ Fe 3+ Cu + Cu 2+ Zn 2+ Pb2+ Pb4+

Anions in Binary Cpds 1- 2- 3- F- fluoride O2- oxide N3- nitride Cl- chloride S2- sulfide P3- phosphide Br- bromide I- iodide

Polyatomic Ions 1- 2- 3- OH- hydroxide CO32- carbonate PO43- phosphate NO3- nitrate SO42- sulfate NO2- nitrite SO32- sulfite HCO3- hydrogen carbonate 1+ NH4+ Ammonium

Formation of Anions 7.1

Metal Ions with more than 1 Ionic Charges Formula Stock Name Cu+ Copper (I) ion Cu 2+ Copper (II) ion Fe 2+ Iron (II) ion Fe 3+ Iron (III) ion Pb 2+ Lead (II) ion Pb 4+ Lead (IV) ion Cr 2+ Chromium (II) ion Cr 3+ Chromium (III) ion Mn 2+ Manganese (II) ion Mn 4+ Manganese (IV) ion

Highly Unequal Sharing Ionic Bond e- transfer results in the formation of 1 +ve ion and 1 -ve ion. Metal ~ nonmetal The bond formed by the 2 oppositely charged ions. Cation ~~anion Electrostatic attraction

A Model of Bonding By forming bonds, atoms acquire an octet of e- and the stable e- confign of a noble gas. Atoms are often more stable when they’re bonded in cpds than when they’re free atoms.

Formation of Ionic Cpds Ionic Bonds The electrostatic forces that hold ions together in ionic cpds are called ionic bonds.

Physical Properties of Ionic cpd Covalent cpd Example NaCl CO 2 State at room temperature Crystalline solid Solid, liquid or gas Melting point High Low Conduct electricity in liquid state Yes No Water solubility Usually High Conduct electricity in aq soln

Atomic View of Metallic Bonding Each atom in this model of a Gp 2 metal releases its 2 valence e- into a sea of e- to be shared by all of the metal atoms. Delocalized e- 

Sea of Valence e- The valence e- of metal atoms are loosely held by the +vely charged nucleus. In metallic bonding, metal atoms don't lose valence e-. Not forming cpds

Sea of Valence e- metallic bond Metal atoms release valence e- into a sea of e- shared by all of the metal atoms. Attraction between e- sea and the metal atoms (cations)

Atomic View of Metallic Bonding Bonding in metals is not rigid. As a metal is struck by a hammer, the atoms slide thru the e- sea to new positions while continuing to maintain their connections (bond) to each other. The same ability to reorganize explains why metals …

Properties That Reflect Metallic Bonding Conductors of electricity the valence e- are freely moving and is charged. Electric current is a flow of e-

Properties That Reflect Metallic Bonding Metals and alloys are malleable made into thin sheets

Properties That Reflect Metallic Bonding Metals are Ductile can be drawn into wires.

CST problem 1 When cations and anions join, they form what kind of chemical bond? A ionic B hydrogen C metallic D covalent

CST problem 2 The reason salt crystals, such as KCl, hold together so well is because the cations are strongly attracted to A neighboring cations B the protons in the neighboring nucleus C free electrons in the crystals D neighboring anions.

The End

Properties of Ionic Cpds The coordination # of an ion the # of ions of opposite charge that surround the ion in a crystal. In NaCl, each ion has a coordination # of 6.

Properties of Ionic Cpds In CsCl, each ion has a coordination # of 8. In TiO2, each Ti4+ ion has a coordination # of 6, while each O2- ion has a coordination # of 3.

Formation of Ionic Cpds NaCl is the chem formula for sodium chloride.

Properties of Ionic Cpds Ionic cpds can conduct an electric current when melted or dissolved in water.