A. Atomic Mass Atomic mass = # p+ + n0 The average atomic mass is the number at the bottom of each square Found by averaging the natural abundances of its isotopes Atomic mass = # p+ + n0

B. Isotopes Mass # Atomic # Atoms of the same element with different mass numbers. Nuclear symbol: Mass # Atomic # Hyphen notation: carbon-12

B. Isotopes © Addison-Wesley Publishing Company, Inc.

B. Isotopes Chlorine-37 atomic #: mass #: # of protons: # of electrons: # of neutrons: 17 37 20

Organization Metallic Character Rows & Columns Table Sections Ch. 3 - The Periodic Table Organization Metallic Character Rows & Columns Table Sections

A. Metallic Character Metals Nonmetals Metalloids

Metals Good conductors of heat and electricity Found in Groups 1 & 2, middle of table in 3-12 and some on right side of table Have luster, are ductile and malleable

Alkali Metals Group 1 Very reactive Form +1 ions Cations Examples: H, Li, Na

Alkaline Earth Metals Group 2 Reactive Form 2+ ions Cations Examples: Be, Mg, Ca, etc

Transition Metals Groups 3-12 on the Periodic Table Much less reactive than Alkali or Alkaline Earth Metals Only 1 that is a liquid at room temp Mercury – Hg Examples: Cr, Co, Ni, Fe, Cu, Ag, Au

Nonmetals Not good conductors Found on right side of periodic table – AND hydrogen Usually brittle solids or gases

Halogens Group 17 Very reactive Form 1- ions Anions Examples: F, Cl, Br, etc

Noble Gases Group 18 Unreactive, inert, “noble” Have a 0 charge, no ions Examples: He, Ne, Ar, Kr, etc

Metalloids Sometimes called semiconductors Form the “stairstep” between metals and nonmetals Have properties of both metals and nonmetals Examples: B, Si, Sb, Te, As, Ge

State at Room Temperature Most are solid State changes with change in temperature

B. Table Sections Representative Elements Transition Metals Inner Transition Metals

B. Table Sections Overall Configuration Lanthanides - part of period 6 Actinides - part of period 7

C. Columns & Rows Group (Family) Period

Periodic Trends Terms Dot Diagrams Ch. 3 - The Periodic Table Periodic Trends Terms Dot Diagrams

A. Terms Periodic Law Properties of elements repeat periodically when the elements are arranged by increasing atomic number.

A. Terms Valence Electrons Atomic Radius e- in the outermost energy level Atomic Radius Measure of the size of an atom

B. Periodic Trends Group # = # of valence e- (except He) Families have similar reactivity. Period # = # of energy levels 1A 2A 3A 4A 5A 6A 7A 8A

C. Lewis Diagrams Dots represent the valence e- EX: Sodium EX: Chlorine