Download Section 6.1 Development of the Modern Periodic Table

Section 6.1 Development of the Modern
Periodic Table
• Trace the development of the periodic table.
• Identify key features of the periodic table.
atomic number: the number of protons in an atom
The periodic table evolved over
time as scientists discovered more
useful ways to compare and
organize the elements.
Section 6.1 Development of the Modern
Periodic Table (cont.)
periodic law
group
period
representative elements
transition elements
metal
alkali metals
alkaline earth metals
transition metal
inner transition metal
lanthanide series
actinide series
nonmetals
halogen
noble gas
metalloid
Development of the Periodic Table
• In the 1700s, Lavoisier compiled a list of all
the known elements of the time.
Development of the Periodic Table (cont.)
• The 1800s brought large amounts of
information and scientists needed a way to
organize knowledge about elements.
• John Newlands proposed an arrangement
where elements were ordered by increasing
atomic mass.
Development of the Periodic Table (cont.)
• Newlands noticed
when the elements
were arranged by
increasing atomic
mass, their
properties repeated
every eighth
element.
Development of the Periodic Table (cont.)
• Meyer and Mendeleev both demonstrated
a connection between atomic mass and
elemental properties.
•Mendeleev is considered the “father of
the periodic table”
•Is the table arranged by increasing atomic
mass today???
• Moseley rearranged the table by
increasing atomic number, and resulted
in a clear periodic pattern.
• Periodic repetition of chemical and
physical properties of the elements when
they are arranged by increasing atomic
number is called periodic law.
Development of the Periodic Table (cont.)
The Modern Periodic Table
• The modern periodic table contains boxes
which contain the element's name, symbol,
atomic number, and atomic mass.
The Modern Periodic Table (cont.)
• Vertical columns of elements are called
___________
• Rows of elements are called _________
• Elements in groups 1,2, and 13-18 possess a
wide variety of chemical and physical
properties and are called the representative
elements (or the main group elements).
• Elements in groups 3-12 are known as the
transition metals.
The Modern Periodic Table (cont.)
• Elements are classified as metals,
non-metals, and metalloids.
• Metals are elements that are generally shiny
when smooth and clean, solid at room
temperature, and good conductors of heat
and electricity.
• Alkali metals are all the elements in group 1
except hydrogen, and are very reactive.
• Alkaline earth metals are in group 2, and
are also highly reactive.
The Modern Periodic Table (cont.)
• The transition elements are divided into
transition metals and inner transition
metals.
• The two sets of inner transition metals are
called the lanthanide series and actinide
series and are located at the bottom of the
periodic table in the f block.
The Modern Periodic Table (cont.)
• Non-metals are elements that are
generally gases or brittle, dull-looking
solids, and poor conductors of heat and
electricity.
• Group 17 is composed of highly reactive
elements called halogens.
• Group 18 gases are extremely unreactive and
commonly called noble gases.
The Modern Periodic Table (cont.)
• Metalloids have physical and chemical
properties of both metals and non-metals,
such as silicon and germanium.
Section 6.2 Classification of the Elements
• Explain why elements in
the same group have
similar properties.
• Identify the four blocks
of the periodic table
based on their electron
configuration.
valence electron:
electron in an atom's
outermost orbitals;
determines the chemical
properties of an atom
Elements are organized into different
blocks in the periodic table according
to their electron configurations.
Organizing the Elements by Electron
Configuration
• Valence electrons: electrons in the
highest principal energy level
• All group 1 elements have one valence
electron.
Section 6.3 Periodic Trends
• Compare period and
group trends of several
properties.
• Relate period and group
trends in atomic radii to
electron configuration.
principal energy level:
the major energy level of
an atom
ion
ionization energy
octet rule
electronegativity
Trends among elements in the periodic
table include their size and their ability
to lose or attract electrons
Atomic Radius
• Atomic size is a periodic trend influenced
by electron configuration.
• For metals, atomic radius is half the distance
between adjacent nuclei in a crystal of the
element.
Atomic Radius (cont.)
• For elements that occur as molecules, the
atomic radius is half the distance between
nuclei of identical atoms.
Atomic Radius (cont.)
• There is a general decrease in atomic
radius from left to right, caused by
increasing positive charge in the nucleus.
• As an atom gets closer to having a filled
energy level, it wants to keep its electrons
Atomic Radius (cont.)
• Atomic radius generally increases as you
move down a group.
• As you add energy levels, they get further
from the nucleus
Ionic Radius
• An ion is an atom or bonded group of
atoms with a positive or negative charge.
• Why would an atom want to gain or lose an
electron?
Ionization Energy (cont.)
• The octet rule states that atoms tend to
gain, lose or share valence electrons in order
to acquire a full set of eight valence
electrons.
• The octet rule is useful for predicting what
types of ions an element is likely to form.
• For example, How many electrons does
Oxygen need to get an octet?
• What would be the easiest way for Na to
get an octet?
Ionization Energy
• Ionization energy is defined as the energy
required to remove an electron from a
gaseous atom.
• The energy required to remove the first
electron is called the first ionization energy.
Ionization Energy (cont.)
Ionization Energy (cont.)
• Removing the second electron requires
more energy, and is called the second
ionization energy.
• Each successive ionization requires more
energy, but it is not a steady increase.
Ionization Energy (cont.)
• The ionization at which the large increase
in energy occurs is related to the number of
valence electrons.
• First ionization energy increases from left to
right across a period.
• First ionization energy decreases down a
group because atomic size increases and
less energy is required to remove an electron
farther from the nucleus.
Ionization Energy (cont.)
Ionization Energy (cont.)
• The electronegativity of an element
indicates its relative ability to attract
electrons in a chemical bond.
• Electronegativity decreases down a group
and increases left to right across a period.
Electronegativity