Presentation on theme: "Chapter 7 Ionic and Metallic Bonding"— Presentation transcript:
1 Chapter 7 Ionic and Metallic Bonding Chapter 4 Atoms and Chemical Bonding
2 Valence Electrons Highest energy level Determine chemical properties [Ne]4s2 3d10 4p5 - Bromine7 valence e-Representative elements = group #
3 Valence Electrons Lewis (1916) 2345678Valence electrons are the electrons in the atom’s highest numbered energy level.
4 Electron dot Structures Lewis dotShow electrons as dots•Ca• •B•Fill in each side with one dot before you double up
5 Octet Rule In forming compounds atoms gain, lose, or share in such a way that they achieve the electron configuration of the nearest noble gas in the periodic table.Noble gases are stablehave eight electrons in the outermost level
6 Ionic Bonding Atoms lose or gain electrons to form ions Cations are positive ionsmetals generally form cationsAnions are negative ionsnon-metals generally form anionsIonic compounds are held together by electrostatics- the positive charge of the cation attracting the negative charge of the anion.
15 Polyatomic IonsPolyatomic means “many-atom” ion
16 Metallic bonds Closely packed cations Valence e- are free and can drift from one metal to anotherMeallic bonds consist of the attraction of ther free-floating valence e- for the positively charged metal ions
17 Metallic bonds (e-) they do not "belong" to any one atom are part of the whole metal crystal*Metallic bonds are best characterized by the phrase "a sea of electrons"*
18 Metallic properties electrons flow explains characteristics of metals: - Metals are good conductors of heat and electricity.mobility of the electrons.- The "cement" effect of the electrons determines the hardness Some- Metals are lustrous. due to the uniform way that the valence electrons absorb and re-emit light energy.- Metals are malleable (can be flattened) and ductile (can be drawn into wires)because the metal cations and electrons can "flow" around each other, without breaking the crystal structure.
19 Alloys Mixture of two or more elements, at least one is a metal Example: brass = copper and zincProperies are better than those of the single elementsSterling silver = siler and copperDurable /no tarnishSteel is a very important alloyiron, carbon, boron, chromium, manganese, and more