Transcript notes on periodic table

PERIODIC TABLE
Chapter 5 Section 4
Dmitri Mendeleev
• Elements in columns
in order of increasing
atomic mass and
rows according to
similar properties.
• Developed the
periodic table.
Henry Moseley
• Found atomic
number.
• Listed elements in
order of atomic
number NOT mass.
Modern Periodic Table
•
•
•
•
Element identified by symbol.
Atomic number on top.
Atomic mass and name at bottom.
Listed in order of increasing atomic number,
from left to right and from top to bottom.
• Periodic Law—when elements are arranged in
order of increasing atomic number, there is a
periodic repetition of their physical and chemical
properties.
Parts of the Periodic Table
• Periods—horizontal
rows.
• Group—vertical
columns (same
physical and chemical
properties).
PERIODIC TABLE DETAILS
• Group A—representative elements, exhibit
a wide range of physical and chemical
properties.
• Group B—transition metals and inner
transition metals (in the valley).
Representative Elements
• Group 1-A—react vigorously with water
and are called Alkali Metals.
• Group 2-A—Alkaline Earth Metals
• Metals (left side)—high electrical and heat
conductivity, high luster when clean,
ductile, and malleable.
More Representative Elements
• Group 7-A—Halogens
• Group 8-A or 0—Noble Gases, few chemical
reactions.
• Non-metals (upper right corner)—gases, brittle,
solid @ room temp., generally nonlustrous, poor
conductors of electricity (insulators).
• Metalloids (along the stair step)—dull, brittle,
semi-conductors, in between metals and
nonmetals.
Atomic radii
• The size of the atom
• Increases moving down the group/family
(adding an energy level)
• Decreases moving across the period
(Charge of the nucleus
increases, pulling
in the electrons more)
Electronegativity
• The ability of an atom in a molecule to
attract a shared electron pair to itself
• Atoms want 8 valence electrons. Called
the octet rule.
• Metals lose electrons (become cations) to
fill the outer energy level
• Nonmetals gain electrons (become
anions) to fill the outer energy level
Ionization energy
• The energy needed to remove an electron.
• Some atoms will not give up the electrons.
(nonmetals)
• Some give up electrons easily. (metals)
• Most reactive metal is Francium
• Most reactive nonmetal is Fluorine