Transcript R The Periodic Table

R The Periodic Table
D’Mitri Mendeleev
• 1860’s
• First to publish
• Placed similar elements in same
vertical column
• Left open spaces for elements he
predicted would someday be
discovered
Describing the Periodic Table
• The periodic table is a chemistry
reference
• It arranges all the known elements in
an informative grid
• Elements are arranged left to right
and top to bottom in order of
increasing atomic number
• This order usually coincides with
increasing atomic mass
Describing the Periodic Table
• The Table's pattern and arrangement
shows the arrangement of electrons in
the atom.
• Elements have different atomic
numbers - the number of protons or
electrons increases up the table as
electrons fill the shells.
• Elements have different atomic
masses - the number of protons plus
neutrons increases up the table.
Families on the Periodic Table
• Elements on the periodic table can be
grouped into families bases on their
chemical properties.
• Each family has a specific name to
differentiate it from the other families in
the periodic table.
• Elements in each family
react differently with
other elements.
Columns
• The vertical (up and
down) columns of the
periodic table (there are
18) are called groups or
families.
• Elements in the same
group or family have
similar characteristics
or properties.
Rows
• The horizontal rows of the periodic
table are called periods.
• Elements in a period are not alike in
properties.
• The first element in a period is usually
an active solid, and the last element in
a period is always an inactive gas.
Rows
• Atomic size (number of protons)
increases from left to right across a
period.
• Atomic mass (number of protons &
Neutrons) increases from left to right
across a period.
• The period number of an element
signifies the highest energy level an
electron in that element occupies.
Rows
• Electrons are added one at a time
moving from left to right across a
period.
• The electrons on the outermost shell
have increasingly strong nuclear
attraction, so the electrons become
closer to the nucleus.
Describing the Periodic Table
Interpreting the Periodic Table
Interpreting the Periodic Table
Interpreting the Periodic Table
• The number of protons in an atom
tells what element it is.
• The number of protons in an atom is
referred to as the atomic number of
that element.
Interpreting the Periodic Table
Atomic Symbol:
• The atomic symbol is one or two
letters chosen to represent an element
("H" for "hydrogen," etc.).
• These symbols are used every where
in the world
• Usually, a symbol is the abbreviation
of the element or the abbreviated
Latin name of the element.
Interpreting the Periodic Table
Atomic Mass:
• The atomic mass is the average mass
of an element in atomic mass units
("amu").
• Though individual atoms always have a
whole number of amu’s, the atomic
mass on the periodic table is shown as
a decimal number because it is an
average of all the isotopes of an
element.
Interpreting the Periodic Table
Mass Number:
• The sum of the protons and neutrons
that make up that nucleus.
• The mass number is different for each
isotope of an element.
Groups and Periods
Alkali Metals
•
Very reactive metals that do not occur freely in nature
•
Malleable, ductile, good conductors of heat and electricity,
solids at room temperature
•
Have low densities and low melting points
•
Softer than most other metals
•
Can explode if they are exposed to water
•
Used to produce chemicals, metals, soap, glass, ceramics, and
petroleum products
Groups and Periods
Alkaline Earth Metals
• Metals
• Very Reactive (give up 2 electrons during
reactions)
• Never found free in nature
Groups and Periods
Transition Metals
• ductile and malleable,
and conduct electricity
and heat
• iron, cobalt, and nickel,
are the only elements
known to produce a
magnetic field
• Used in jewelry, industry
(copper, steel, iron),
technology, light bulbs,
and in the food we eat
• Less reactive than most
metals
Groups and Periods
Other Metals
• are ductile and malleable
• are solid, have a relatively high density,
and are opaque
Groups and Periods
Metalloids
•Have properties of both metals and nonmetals
•Appearance will vary
•Some of the metalloids, such as silicon and
germanium, are semi-conductors. This means
that they can carry an electrical charge under
special conditions. This property makes
metalloids useful in computers and
calculators.
• Conduct better than nonmetals but not as well as
metals
•NOTE: any element above 92 is too unstable to
occur in nature and must be done in a lab, scientist
were able to predict existence of elements (neon
and germanium before they were even discovered
Groups and Periods
Nonmetals Metals
•not able to conduct electricity or heat very
well
•exist in two of the three states of matter at
room temperature: gases (such as oxygen) and
solids (such as carbon).
•very brittle, and cannot be rolled into wires or
pounded into sheets
•have no metallic luster, and do not reflect
light.
Halogens
Groups and Periods
• halogen" means "salt-former" and compounds
containing halogens are called "salts"
• Very reactive nonmetals that form salts when
combined with many metals
• Very reactive; often bond with elements from group one.
• Used to kill harmful micro-organisms in hospitals,
to purify drinking water, and prevent growth of
algae in swimming pools.
•exists in all three states
•Solid- Iodine, Astatine
•Liquid- Bromine
•Gas- Fluorine,
Chlorine
Groups and Periods
Noble Gases
• Exist as gases, non-metals
• 8 electrons on outer shell=
full
• Not reactive with other
elements.
Groups and Periods
Rare Earth Metals
• The Rare Earth Metals are typically silver, silverywhite, or gray metals.
• Good conductors of electricity
• 2 Subgroups
– Lanthanide Series: many forms, some with magnetic
properties
– Actinide Series
• All are radioactive