Chapter 5
Stowe Periodic Table
A Spiral Periodic Table
“
“Mayan” Mayan”
Periodic
Periodic
Table
John Newlands
In 1865 English chemist John Newlands arranged
the known elements according to their
Patterns in Newland’s table
Newland noticed that the
properties of the elements
repeated themselves every 8
elements.
Mendeleev’s Periodic Table
Mendeleev’s Periodic Table
Dimitri Mendeleev
In 1869 the Russian
chemist Mendeleev took
Newland’s ideas a step
further
Mendeleev is known as
the father of the modern
How Mendeleev arranged his table
:
He began to arrange the elements by increasing atomic mass. He noticed that as he did this
that there was a repeating pattern of properties of the elements. So he put elements with the
Mendeleev’s Predictions
When Mendeleev was arranging his table, many elements had not been discovered yet. So he left spaces blank on the table and predicted the
properties of elements when they were
Henry
Moseley
Henry Moseley took Mendeleev’s table and changed it by arranging the elements by increasing atomic number. See table for exceptions!!!
Periodic Law – the physical and chemical properties of the elements are periodic functions of their atomic number, that when elements are arranged by
Modern Periodic table
•
The modern
table is
arranged by
increasing
The Periodic Table
The Periodic Table
Period
Group or
family
Period
Elements in groups 1,2 and 13-18
are called the main group
The Properties of a Group:
The Properties of a Group:
the Alkali Metals
the Alkali Metals
•Extremely reactive elements – never
found in nature as a pure element,
always as part of a compound. Elements in this group will form salts with
non-metals – Properties:
•Shiny •Soft
Why do alkali metals behave in the same way and have the same physical and chemical properties?
Because their electron
configurations are similar. All alkali metals end is an s1
configuration.
Na: 1s22s22p63s1
Reason for alkali metals
reactivity
Alkali metals want to lose the s1 electron in
the outermost energy level - this way they have an electron configuration like a noble gas!
Example: Na: 1s22s22p63s1
Videos of Alkali metals
Brainiac
https://www.youtube.com/watch?v=m55kg yApYrY
Disposal of Sodium after WW II
Hydrogen is a special element!
Hydrogen is unique – it is in group 1 because its electron configuration is
similar to the alkali metals but it is not
considered to be an alkali metal!
Hydrogen is the most common element in the
Stars are composed of hydrogen
Like the alkali metals below it on
the table hydrogen is a very
reactive element!
Group 2 – Alkaline Earth Metals
• These elements are:
• harder than alkali metals • good conductors
• shiny
• reactive metals
• very light but strong! • Not found in nature as
s block elements
Elements in groups 1 & 2 are
also called s block elements
d-block elements – Transition metals
Elements in the d-block are also called
transition metals. Groups 3-12
They tend to have the following properties:
•Excellent conductors
•Shiny
•Not very reactive
•Do not easily form compounds compared to alkali or alkaline earth metals
Special transition metals
•
Gold, silver, nickel,
•
Titanium:
Used to make
replacement
Tungsten
This element has the highest melting point (6192 F) and is
used in incandescent light bulbs
Also because of its high strength its used as in the
Mercury
The only metal that is a liquid at room temperature
Used in thermometers, barometers, some electrical
The p – block elements
The p-block elements contains:
•
Metals like aluminum and tin
Properties
Properties
of Nonmetals
of Nonmetals
Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
Nonmetals poor conductors of
heat and electricity (insulators)
Nonmetals tend to be brittle When solid are usually dull
Many nonmetals are gases at
Examples of Nonmetals
Examples of Nonmetals
Sulfur, S, was once known as “brimstone”
Microspheres of phosphorus, P, a reactive nonmetal
Most of the non-metals are
gases
Group 17 - Halogens
These elements have the following properties:
•Extremely reactive, like to react with alkali
and alkali earth metals to form salts
•All have an electron configuration of s2p5
•Fluorine and Chlorine are gases at room
Uses of halogens
• Chlorine, bromine
and iodine are used as disinfectants
• Fluorine is used to
strengthen teeth
• Halogens are also
Gallium
•A p-block metal that is
not a great conductor, it is often used as a
semiconductor in electronics.
•An interesting property
of gallium is that it melts just above room
Aluminum
•
Another p-block metal –
known as a lightweight
metal that is very strong and
resists corrosion.
•
It is used in automobiles,
trucks, aircraft, trains, cans,
foil and construction
Lead
A p-block metal that is dull, very soft and malleable and very heavy – has been used for thousands of years by man in plumbing (the symbol Pb comes from the Latin word
plumbum), in bullets, it makes
excellent pigments in paint, its high density makes it ideal for shielding of different forms of radiation. Lead is also used for electrolysis in car
Negatives of lead
While lead has many applications, it is a
dangerous metal for human beings!
Lead can cause damage to nervous system, blood and
Noble Gases These elements are special in that they do not react with anything. This is because they have
Uses of Noble Gases
• Helium is used for balloons and
blimps
Properties of Metalloids
Properties of Metalloids
Metalloids straddle the border between metals and nonmetals on the periodic table. Also
known as semiconductors
They have properties of both metals and
Silicon, Si – A Metalloid
Silicon, Si – A Metalloid
Silicon has metallic luster
Silicon is brittle like a nonmetal Silicon is a semiconductor of
Arsenic
The f-block elements:
Lanthanides and Actinides
Elements 58-71 are known as the lanthanides – they are shiny, reactive metals, found in the Earth’s crust. These elements are also known as the rare earth
metals because they are so scarce! Not many common uses for these metals.
Elements 90-103 are known as the actinides – all
Periodic Trends
The word
trend
means a change in a
general direction.
The periodic table has many trends
that can be explained how the
Trend: Atomic Size
The size of an atom is dependant on the
electron clouds around the nucleus. The nucleus of an atom is extremely small and the closest electron is very far away. If the nucleus of the a
hydrogen atom was the size of a basketball its electron would be thousands of miles away. All
Trend within a group
Going down a group the size of the atom increases dramatically.
This is because there are layers of orbitals (like an onion) and the outermost electrons do not
Trend within a period
Within a period the size of the elements
generally tend to decrease but there are some exceptions.
The reason for the decrease is due to the greater pull from the nucleus and the desire for the
Electronegativity
Electronegativity is defined as an element’s ability to gain electrons for chemical
bonding.
Trends for electronegativity
Going down a group electronegativity of those elements decreases. There is less of a pull from
the nucleus and the element is less likely to want to gain electrons
Going across a period from left to right there is more pull from the nucleus and the outer most
Trend for valence electrons in
the main group elements
Valence electrons are electrons in the outer most energy levels – for the main group
elements these are the electrons in the
outermost s & p orbitals!