Transcript Periodic Table Families

Chapter 6
The Periodic Table
Ms. Wang
Lawndale High School
Section 6.1 - Organizing the Elements
 By
the 1700’s, only about 13
elements had been identifies

Chemists used the properties of
elements to sort them into groups
 In
1829, J.W. Dobereiner published a
classification system with elements
grouped into set of three based upon
similar chemical properties
Mendeleev’s Periodic Table
 From
1829 to 1869, many different
systems were proposed, but none
gained wide acceptance
 In
1869, Dmitri Mendeleev arranged
the elements in his periodic table in
order of increasing atomic mass,
based upon repeating properties
The Periodic Law

In the modern periodic table,
elements are arranged in order of
increasing atomic number
 Periodic
Law – when elements are
arranged in order of increasing
atomic number, there is a periodic
repetition of their physical and
chemical properties
Metals, Metalloids and Nonmetals
(Red ladder on the periodic table)
 Elements
can be grouped into three
broad classes based on their
general properties
 Metals
 Nonmetals
 Metalloids
 Metals:
elements that are generally
solid at room temperature, have a
grayish color and shiny surface, and
conduct heat and electricity
Nonmetals:
elements that have
varying properties but are generally
poor conductors of heat and electricity
 Metalloids:
elements with some
properties of metals and and
nonmetals
Section 6.2 - Classifying the Elements
(Page 162-163)



The periodic table displays the symbols
and names of the elements, along with
information about the structure of their
atoms
Element symbols that are printed in black
are solid at R.T., blue are liquid at R.T.,
and red are gasses at R.T.
Some elements are printed in green,
which means that they are not found in
nature
The 7 Groups of the Periodic Table
1.
2.
3.
4.
5.
6.
7.
Alkali Metals (Group 1A)
Alkaline Earth Metals (Group 2A)
Chalcogens (Group 6A)
Halogens (Group 7A)
Noble Gases (Group 8A)
Transition Metals (Group B)
Inner Transition Metals
(Lanthanides and Actinides)
Electron Configurations in Groups

Elements can be sorted into noble
gases, representative elements,
transition metals, or inner transition
meals based on their electron
configuration

Noble Gases always have their s and
p sublevels completely filled with
electrons, which makes them
relatively inactive
Representative Elements

Representative Elements are Groups
1A through 7A because they display
a wide range of physical and
chemical properties
 For
any representative element, its
group number always equals the
number of electrons in the highest
occupied energy level (Valence Shell)
Transition Metals
 Transition
Metals are characterized
by the presence of electrons in the d
orbital
 Inner
Transition Metals are
characterized by the presence of
electrons in the f orbital
Section 6.3 – Periodic Trends


Properties of elements are related to
the location of elements in the
periodic table
Four periodic trends:
–Atomic Radius
–Ionization Energy
–Electron Affinity
–Electronegativity
1. Atomic Radius
 One-half
of the
distance from
center to center
of two atoms of
the same
element
Atomic
Radius
1. Atomic Radius
What do you notice about the atomic radii
of the elements on the periodic table?
Atomic Radius Practice
 Which
element has a greater atomic
radius?
–F or Cs
–Ga or K
–Kr or Rb
 Put these elements in order of
increasing atomic radius
– Ba, Si, Fr, W, O, Ag
Ions
 Remember
that atoms that are
electrically neutral have equal
number of protons and electrons
 Some
compounds are composed of
particles called ions.
 Ions
are atoms that have a positive
or negative charge.
Ions
 Positive
and negative ions form when
electrons are transferred between
atoms

Cation – an ion with a positive charge
 Anion
– an ion with a negative charge
2. Ionization Energy

The energy required to remove an
electron from an atom
-
Lithium atom
+
Lithium Ion
2. Ionization Energy
 Elements
with
low ionization
energy are
good
conductors of
electricity
2. Ionization Energy

What trend do you notice about the ionization
energy of the elements on the periodic table?
Ionization Energy Practice
 Which
of these elements has a
greater ionization energy?
–Ar or Kr
–Al or Na
–S or Rb
 Put these elements in order of
increasing ionization energy
–Si, Cs, He, Ca, P, O
Ionic Size
 Cations
are always smaller than the
atoms from which they form
 Anions
are always larger than the
atoms from which they form
 WHY?
(Hint: think about the electron
cloud of an atom)
 Which
Al3+, I
is larger? Na or Na+, Al or
or I-, S or S2-
3. Electron Affinity

What trend do you notice about the electron
affinity of the elements on the periodic table?
4. Electronegativity

The tendency of an atom to attract electrons
to itself when in a compound
4. Electronegativity
What trend do you notice about the electronegativity of
the elements on the periodic table?
Electronegativity Practice
 Which
element has greater
electronegativity?
–Na or F
–Ca or C
–Al or Mg
 Put these elements in order of
increasing electronegativity
–Sr, Al, Ca, K, Cl, F
Homework
Chapter 6 Assessment (Page 181)
#’s 26-46, 48, 49, 52, 64