Download The Periodic Table

History of The Periodic Table
Organizing the Elements
• Chemists used the properties of
elements to sort them into groups.
• JW. Dobreiner grouped elements into
triads.
• A triad is a set of three elements with
similar properties.
Mendeleev’s Periodic Table
• In 1869, a Russian
chemist and
teacher published a
table of the
elements.
• Mendeleev arranged
the elements in the
periodic table in
order of increasing
atomic weight.
Henry Moseley
In 1913, through his work with X-rays, he
determined the actual nuclear charge
(atomic number) of the elements. He
rearranged the elements in order of
increasing atomic number.
1887 - 1915
The periodic table is made up of rows and columns of elements.
 A row is called a period
 A column is called a group or a family
• Across the rows (period), the elements
have a feature that changes regularly
• Down the column (group), the elements
are exactly the same in some way
• How difficult do you think it was to
organize all the elements into the periodic
table?
The Periodic Law
In the modern periodic
table elements are
arranged in order of
increasing atomic
number.
Periodic Law states:
When elements are
arranged in order of
increasing atomic
number, there is a
periodic repetition
of their physical and
chemical properties.
Groups/Families
 Columns of elements are called groups or families.
 Elements in each group have similar but not identical
properties.
 For example, lithium (Li), sodium (Na), potassium (K),
and other members of group IA are all soft, white,
shiny metals.
 All elements in a group have the same number of
valence electrons.
Elements in each group have similar but not
identical properties
 Elements are placed in columns by
similar properties.
 Alkali Metals
 Group 1
 ALL elements in Group 1
have 1 electron in their
outer shell
 They are shiny, have the
consistency of clay, and
are easily cut with a knife
Alkali Metals
 They are the most
reactive metals.
 They react violently
with water.
 Alkali metals are
never found as free
elements in nature.
They are always
bonded with another
element.
 Alkali Earth Metals
 Group 2
 ALL elements in Group 2
have 2 electrons in their
outer shell
Alkaline Earth Metals
 They are never found uncombined in nature.
 Boron Family
 Group 13
 ALL elements in Group 13
have 3 electrons in their
outer shell
 Carbon Family
 Group 14
 ALL elements in Group 14
have 4 electrons in their
outer shell
 Nitrogen Family
 Group 15
 ALL elements in Group 15
have 5 electrons in their
outer shell
 Oxygen Family
 Group 16
 ALL elements in Group 16
have 6 electrons in their
outer shell
 Halogens
 Group 17
 ALL elements in Group 17
have 7 electrons in their
outer shell
 Noble Gases
 Group 18
 ALL elements in Group 18
have 8 electrons in their
outer shell
Write a 3 sentence
summary of how the
groups on the periodic
table are organized
Periods
 Each horizontal row of elements is called a
period.
 The elements in a period are not alike in
properties.
 properties change greatly across even given
row.
• The elements in a period are not alike in properties
• The first element in a period is always an extremely
active solid. The last element in a period, is always
an inactive gas.
 Period 1
 Each element has space for one
shell of electrons
 Period 2
 Each element in this period has two
shells of electrons
 Period 3
 Each element in this period has 3
shells for electrons
 Period 4
 Each element in this period has 4
shells for electrons
 Period 5
 Each element in this period has 5
shells for electrons
 Period 6
 Each element in this period has 6
shells for electrons
The Lanthanides are part of period 6
 Period 7
 Each element in this period has 7
shells for electrons
The Actinides are part of period 7
Practice
 Elements are grouped into three broad
classes based on their general
properties.
1. Metals
2. Nonmetals
3. Metalloids.
METALS
Non-METALS
METALLOIDS
Properties of Metals
 Metals are:
 good conductors of heat and
electricity
 Shiny
 ductile (can be stretched
into thin wires)
 malleable (can be pounded
into thin sheets)
 Solid at room temperature
except Hg
 React with acids
METALS
Properties of Non-Metals
 Non-metals are
 poor conductors of
heat and electricity
 not ductile or
malleable
 brittle and break
easily
 dull
 Many non-metals are
gases.
Sulfur
Non-METALS
Properties of Metalloids
 have properties of both
metals and non-metals.
 can be shiny or dull.
 conduct heat and electricity
better than non-metals but
not as well as metals.
 ductile and malleable.
Silicon
METALLOIDS
 Transition Elements (Transition Metals)
Transition Metals
 copper, tin, zinc, iron,
nickel, gold, and silver.
 good conductors of heat
and electricity.
Transition Metals




The compounds are brightly colored
used to color paints
have 1 or 2 valence electrons
Some transition elements can lose electrons in their
next-to-outermost level.
 inner transition metals: lanthanides and
actinides – are members of group 2 or 3

.
lanthanides
actinides
Properties of lanthanides
 High melting points and boiling points.
 Very reactive.
 Burn easily in air.
 Belong to period 6
Properties of actinides
 All are radioactive.
 The metals tarnish readily in air.
 Belong to period 7
 Elements above 92 do not exist in nature
but have been manufactured in the lab
Hydrogen
 The hydrogen square sits atop group A1,
but it is not a member of that group.
Hydrogen is in a class of its own.
 It’s a gas at room temperature.
 It has one proton and one electron.
 Hydrogen only needs 2 electrons to fill up its
valence shell.
METAL, NON METAL OR
METALLOID?
Trends in the periodic
table:
Atomic Radius
Ionization Energy
Electronegativity
Reactivity
Atomic Radius
The atomic radius is defined as one-half of the
distance between two bonded nuclei.
Atomic Radius Trend
 Group Trend – As you go down a column,
atomic radius increases.
 Periodic Trend – As you go across a period (L
to R), atomic radius decreases.
atomic radius increases
Atomic Radius
atomic radius decreases
Ionization Energy
 The ionization energy is the energy required to
remove an electron from an atom or ion.
Ionization Energy Trend
 Ionization Energy Decreases as You Move
Down a Group
 Ionization energy tends to increase as you
move from left to right across a period.
Electronegativity
 Not all atoms in a compound share electrons equally.
 Knowing how strongly each atom attracts bonding
electrons can help explain the physical and chemical
properties of a compound
 Linus Pauling, an American chemist, made a scale of
numerical values that reflect how much an atom in a
molecule attracts electrons, called electronegativity
values
Electronegativity
 Electronegativity is the measure of the
ability of an atom in a chemical compound
to attract electrons.
 The atom with the higher electronegativity
will pull on the electrons more strongly
than the other atom will
Electronegativity Trend
 Electronegativity Decreases as You Move
Down a Group
 Electronegativity tends to increase as you
move from left to right across a period.
TRENDS – ATOMIC RADIUS
AND IONIZATION ENERGY
Reactivity Trends
 Different for metals and non metals
 Elements will be reactive depending on
how many electron shells they have and
how low their ionization energy is.
Reactivity Trend For Metals
 The reactivity of the metals in the 1st and 2nd
group increases from the top to the bottom.
 The reactivity of the metals decreases from the
left to the right.
Reactivity trend for Non Metals
 The reactivity of the non metals in the 6th
and 7th group decreases from the top to
the bottom.
The reactivity of the non metals decreases
from the right to the left.
What does this mean?
 Iron is more reactive than Nickel, so it will
react with Nickel
 Iron is less reactive than Potassium, so it
won’t react with Potassium
REACTIVITY OF METALS
COMPLETE
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