Mendeleev First to try and organize elements 1869 published first periodic table Knew about 70 elements at the time Arranged according to similar properties Arranged by increasing atomic mass

Chapter 5.1/5.2 Page 123 introintro clip

Periodic Law The physical and chemical properties of the elements are periodic functions of their atomic masses. This law will be modified Predicted properties for unknown elements. Ge, Sc, Ga

Mosley Periodic patterns fit better when the elements are arranged by increasing atomic number. Periodic Law – the physical and chemical properties of the elements are periodic functions of their atomic numbers. This is the law today...\..\downloaded clips\clips chapter 5\Henry_Moseley_s_Periodic_Table.asf

Noble Gases Discovered in 1894 Non-reactive / stable –Full outer valance level –Full octet –Full s and p sublevels Difficult to find because they are un- reactive. Added a family to Mendeleev’s periodic table

Lanthanides Early 1900’s Pull out Located on bottom of periodic table F block

Actinides Radioactive Pull out Located at bottom of periodic table F block

Periodicity Going down a family Atomic numbers follow a numerical pattern

Review Families or groups are in vertical columns Periods or rows are horizontal rows

Blocks on the periodic table Families 1 and 2 – s block Families – p block Families 2-12 – d block Series lanthanide and actinide – f block

s- block Family 1 Alkali Metals Very reactive Reactive with other elements Never exist as a free element ( alone) React with water Soft silvery

s- block Family 2 Alkaline earth metals Found in crust of earth Less reactive than family 1, but still very reactive. Does not exist as a free element Harder/denser than family 1, but still soft Higher melting points than family 1

d block Metals Less reactive or more stable Many uses ( money, pipes, art, planes) Exist as free elements, Cu, Au, Ag, Pt Denser and harder than families 1 and 2 –Get more dense as you move to the right and more hard as you move to the right

p-block Nonmetals, metals, metalloids Variety of properties Main group elements –s and p blocks –..\..\downloaded clips\clips chapter 5\5.2 alkalki halogen noble.asx..\..\downloaded clips\clips chapter 5\5.2 alkalki halogen noble.asx

p- block Halogens family 17 –Very reactive nonmetals –Want one more electron –Satisfy octet Noble gases family 18 –Stable as full s and p sublevels –Has octet Metalloids –6 elements –B, Si, Ge, As, Sb, Te

Properties of p-block Difficult to make generalities due to the variety of elements in the p block In-between s and d for hardness and density Only free standing element is Bi. Usually found in compounds with other elements summary clip

“Salts” Family 16 and 17 react with families 1 and 2 to form “salts” fun quiz!