Periodic Table

Dmitri Mendeleev

In 1869 a total of 63 elements were discovered

Mendeleev, a Russian scientist, discovered a set of

patterns that applied to all the elements

Knew some elements have similar chemical and

physical properties

Some 19th Century History…

1842: Anesthesia used for the first time

1848-1858: California Gold Rush

1861-1865: American Civil War

1859: Charles Darwin publishes On the Origin of Species

1865: US President Abraham Lincoln is assassinated

1865: Gregor Mendel publishes his laws of inheritance

The Modern Periodic Table The periodic table was changed and rearranged as scientists

learned more about the atomic structure.

Contains over 100 elements

Organized differently from Mendeleev’s table

Elements are arranged in order of increasing atomic number

Properties of an element can be predicted from its location

on the periodic table

PeriodsPeriods = Horizontal rows

From left to right, properties of the elements change in a pattern

There are 7 periods

Some elements in periods 6 and 7 are placed off the table to

save space

Groups Groups = Vertical Columns

A group is also known as a family (elements with

similar characteristics)

Example: Elements in group 1 react violently with

elements in Group 2

Group 1

Name Alkali Metals

List of Elements Li, Na, K, Rb, Cs, Fr

# Valence Electrons 1

Classified as: Metals

Reactivity Highly Reactive

Properties Soft, silver colored,

shiny, low density

Group 2

Name Alkaline-Earth Metals

List of Elements Be, Mg, Ca, Sr, Ba,

Ra

# Valence Electrons 2

Classified as: Metals

Reactivity Very Reactive

Properties Silver-colored, more

dense

Groups 3-12

Name Transition Metals

List of Elements 21-30, 39-40, 72-80, 104-112

# Valence

Electrons

1 or 2

Classified as: Metals

Reactivity Less Reactive

Properties Shiny, good conductors,

higher densities than

Group 1 or 2

Group 13

Name Boron Group

List of Elements B, Al, Ga, In, Tl

# Valence Electrons 3

Classified as: Metalloids and

Metals

Reactivity Reactive

Properties Solid at Room

Temperature

Group 14

Name Carbon Group

List of Elements C, Si, Ge, Sn, Pb

# Valence Electrons 4

Classified as: Non-metals, metals,

metalloids

Reactivity Varied

Properties Solid at Room

Temperature

Group 15

Name Nitrogen Group

List of Elements N, P, As, Sb, Bi

# Valence Electrons 5

Classified as: Nonmetals, Metals,

Metalloids

Reactivity Varied

Properties All but N is solid at

room temperature

Group 16

Name Oxygen Group

List of Elements O, S, Se, Te, Po

# Valence Electrons 6

Classified as: Metals, Nonmetals, and

Metalloids

Reactivity Reactive

Properties All but O are solid at

room temperature

Group 17

Name Halogens

List of Elements F, Cl, Br, I, At

# Valence Electrons 7

Classified as: Nonmetals

Reactivity Very Reactive

Properties Poor Conductors

Group 18

Name Noble Gases

List of Elements He, Ne, Ar, Kr, Xe, Rn

# Valence Electrons 8

Classified as: Nonmetals

Reactivity Unreactive

Properties Colorless, odorless,

gases at room

temperature

32:49-43:50