Transcript Int. Sci. 9 Modern Periodic Table Powerpoint

Introduction to the
Periodic Table
Atomic Number ● Symbol ● Atomic Weight
Element ● Compound ● Mixture
Common Misconception
 Isotopes
– atoms of the same element
so they have the same ATOMIC #
(protons) & different MASS # (neutrons)
 There is not just 1 “regular” atom
which you see on the Periodic Table
 The symbols on the Periodic Table
represent “average” atoms of elements
– A sample of an element found in nature
contains a mixture of the different isotopes
of that element
I am Dmitri Mendeleev!
I made the PERIODIC TABLE !
What is the PERIODIC TABLE?
o
Shows all known
elements in the universe.
o
Organizes the elements
by chemical properties.
How do you read the
PERIODIC TABLE?
What is the ATOMIC NUMBER?
o
o
The number of
protons found in the
nucleus of an atom
Or
The number of
electrons surrounding
the nucleus of an
atom.
What is the SYMBOL?
o
An abbreviation of
the element name.
What is the ATOMIC MASS?
o
The number of protons
& neutrons in the
nucleus of an atom.
How do I find the number of protons,
electrons, and neutrons in an element
using the periodic table?
o
# of PROTONS
= ATOMIC NUMBER
o
# of ELECTRONS = ATOMIC NUMBER
o
# of NEUTRONS = ATOMIC _ ATOMIC
MASS
NUMBER
The Periodic Law
 Elements
are arranged by increasing
atomic number (# of Protons)
Periodic Law
 Periods
– Each row (7 total)
 Groups – Each column (32 total)
– Properties of elements repeat in a
predictable way when atomic numbers
are used to arrange elements into
groups
Pg 131 in the book fig. 6
Groups
 Elements
in a group have similar
electron configurations
– Electron configurations determine its
chemical properties
– Members of a group in the periodic table
have similar chemical properties
Known as Periodic Law!!!
Elements, Compounds, and
Mixtures
What is an ELEMENT?
o
A substance
composed of a
single kind of atom.
o
Cannot be broken
down into another
substance by
chemical or physical
means.
What is a COMPOUND?
o
A substance in
which two or
more different
elements are
CHEMICALLY
bonded together.
What is a MIXTURE?
o
Two or more
substances that
are mixed
together but are
NOT chemically
bonded.
Classes of Elements
 Solids,
Liquids, or Gases
 Elements that occur naturally and
those that do not – all but 2 w/
atomic # 1-92 occur on Earth
naturally; elements # 93 & higher do
not
 Metals, Nonmetals, and Metalloids
Pg 133 in your textbook
Metals
 Good
conductors of electric current
and heat
– Except for Mercury, metals are solid at
room temp.
Metals






Most solids (Hg is liquid)
Luster – shiny.
Ductile – drawn into thin
wires.
Malleable – hammered into
sheets.
Conductors of heat and
electricity.
Include transition metals –
“bridge” between elements
on left & right of table
Transition Metals
 Elements
that form a bridge between
the elements on the left and right
sides of the table
– Exp. Copper & Silver
– Many are able to form compounds with
distinctive colors
Nonmetals
 Elements
that are poor conductors of
heat & electric current
– Exp. Fluorine is the most reactive
Non-Metals






Properties are generally opposite of
metals
Poor conductors of heat and
electricity
Low boiling points
Many are gases at room temperature
Solid, non-metals are brittle (break
easily)
Chemical properties vary
Metalloids
 Elements
with properties that fall
between those of metals and
nonmetals
– Ability to conduct electric current varies
with temp.
Metalloids



stair-step pattern
Have properties similar to
metals and non-metals
Ability to conduct heat and
electricity varies with temp

Better than non-metals but
not metals
Variation Across a Period:
Left to Right
Physical and Chemical properties
 Atomic size decreases
 Metallic properties decrease
 Ability to lose an electron decreases
 Ability to gain electrons increases

Review
 Elements
are arranged by increasing
Atomic Number (# of P’s)
– Each row = Period
– Each column = Group
 Properties
of elements repeat in a
predictable way when atomic #’s are
used to arrange elements into
groups
Review Continued…
 Atomic
mass depends on the
distribution of an element’s isotopes
in nature an the masses of those
isotopes
 Elements are classified as metals,
nonmetals, and metalloids
 Across a period from left to right, the
elements become less metallic and
more nonmetallic in their properties