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Chemistry 4.2
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4.3
The Periodic Table
Dimitri Mendeleev
Father of the Periodic
o Mendeleev arranged
the elements in his
periodic table in order
of increasing atomic
mass.
o The periodic table
can be used to
predict the properties
of undiscovered
elements.
o Had its problems
Henry Moesley
Father of the Modern Periodic Table
• British Physicist
• Through experimental data,
able to position elements more
properly on the Periodic Table
• Changed the way the PT
appeared
The Periodic Table
• In the modern periodic table, elements are arranged in
order of increasing atomic number.
• Groups arranged based on similarities in properties
Anatomy of
The Periodic Table
o Each
horizontal row
of the
periodic table
is called a
period.
o Within a given
period, the
properties of
the elements
vary as you
move across it
from element
to element.
Anatomy of
The Periodic Table
• Each vertical
column of
the periodic
table is
called a
group, or
family.
• Elements
within a
group have
similar
chemical
and physical
properties.
Families to know
•
•
•
•
•
Group 1A: Alkali Metals
Group 2A: Alkaline Earth Metals
Groups 3-12: Transition Metals
Group 7A: Halogens
Group 8A: Noble Gases
o Look in back of textbook for information on properties that characterize
these families.
What are three broad
classes of elements?
6.1
Metals, Nonmetals, and
Metalloids
Metals, Nonmetals, and
Metalloids
6.1
• Metals, Metalloids, and Nonmetals in the Periodic Table
Metals, Nonmetals, and
Metalloids
6.1
• Metals, Metalloids, and Nonmetals in the Periodic Table
Metals, Nonmetals, and
Metalloids
6.1
• Metals, Metalloids, and Nonmetals in the Periodic Table
Metals, Nonmetals, and
Metalloids
6.1
o Metals
• Metals are good
conductors of heat
and electric current.
o 80% of elements
are metals.
o Metals have a
high luster, are
ductile, and are
malleable.
Metals, Nonmetals, and
Metalloids
• Nonmetals
o In general, nonmetals are poor
conductors of heat and electric
current.
• Most nonmetals are gases at
room temperature.
• A few nonmetals are solids,
such as sulfur and
phosphorus.
• One nonmetal, bromine, is a
dark-red liquid.
Metals, Nonmetals, and
Metalloids
o Metalloids
• A metalloid generally has properties
that are similar to those of metals and
nonmetals.
• The behavior of a metalloid can be
controlled by changing conditions.
Si
As
What are three kinds of
subatomic particles?
Particle
Symbol
Charge
Mass
Location
Protons
p+
+1
1 amu
Nucleus
Neutron
no
No
charge
1 amu
Nucleus
Electrons
e-
-1
negligible
Space around
nucleus
Subatomic Particles
The Atomic
Nucleus
In the nuclear
atom, the protons
and neutrons are
located in the
nucleus.
The electrons are
distributed around
the nucleus and
occupy almost all
the volume of the
atom.
What makes elements
different from one
another
4.3
◦Elements are different because they contain
different numbers of protons.
◦The atomic number of an element is the
number of protons in the nucleus of an atom of
that element.
Atomic Number
4.3
Atomic Number
How do isotopes of an
element differ?
Just
as ice cream
comes in different
flavors, a
chemical element
can come in
different ”flavors”
called isotopes.
Distinguishing Among Atoms
4.3
Isotopes are atoms that have
the same number of protons
but different numbers of
neutrons.
◦Because isotopes of an
element have different
numbers of neutrons, they
also have different mass
numbers.
Isotopes
4.3
 Despite these differences, isotopes are chemically
alike because they have identical numbers of
protons and electrons.
4.3
 The total number of protons and
neutrons in an atom is called the mass
number.
◦The number of neutrons in an atom
is the difference between the mass
number and atomic number.
Mass Number
How do you calculate the atomic
mass of an element?
 The atomic mass of an element is a weighted
average mass of the atoms in a naturally
occurring sample of the element.
 A weighted average mass reflects both the mass
and the relative abundance of the isotopes as
they occur in nature.
Atomic Mass
4.3
◦To calculate the atomic mass of an element,
multiply the mass of each isotope by its natural
abundance, expressed as a decimal, and then
add the products.
Atomic Mass
4.3
 For example, carbon has two stable isotopes:
◦Carbon-12, which has a natural abundance of 98.89%,
and
◦Carbon-13, which has a natural abundance of 1.11%.
Atomic Mass