Download File - Lenora Henderson`s Flipped Chemistry Classroom

Chapter 6
The Periodic Table
Organizing the Elements
6.1
Searching for an Organizing Principle
Key Question
How did chemists begin to organize the known
elements?
They used the properties of elements to sort them into groups.
 J.W. Dobereiner was a German chemist that published a
classification system, in which the known elements were
grouped in triads
 Triad is a set of three elements with similar properties
Mendeleev’s Periodic Table
Key Question
How did Mendeleev organize his periodic table?
He arranged the elements in order of increasing atomic mass.
 Dmitri Mendeleev published his periodic table around the
same time as Lothar Meyer (German chemist); these periodic
tables were identical, but because Mendeleev published his
table first and was able to explain its periodic trends better
his was given the credit.
Today’s Periodic Table
Key Question
How is the modern periodic table organized?
Increasing atomic number
 Henry Moseley determined an atomic number for each known
element
 Groups are vertical
 Periods are horizontal
 Each period corresponds to a principal energy level
 Periodic law is when elements are arranged in order of
increasing atomic number, there is a periodic repetition of
their physical and chemical properties
 Elements that are in the same group have similar chemical
and physical properties
Metals, Nonmetals, and Metalloids
 Scientists must agree on a standard that will be used for
communication purposes, these standards are set by IUPAC
(International Union of Pure and Applied chemistry)
 They numbered the groups from left to right, 1-18
Key Question
What are three broad classes of elements?
Metals, nonmetals, and metalloids
Metals
 Most elements are metals
 Metals are generally good conductors of heat and electricity
 All metals are solids at room temperature, except Hg
 Many metals are ductile, and most are malleable
Nonmetals
 Most nonmetals are gases at room temperature
 There is a greater variation in the properties of nonmetals
than in metals
 Nonmetals are poor conductors of heat and electricity, with
an exception of carbon
 Solid nonmetals tend to be brittle
Metalloids
 Dark line separates the metals from the nonmetals, the
elements along this border are called metalloids
 Metalloids may have properties similar to those of metals and
nonmetals (depends on the condition)
Using the Periodic Table to Determine
States of Matter
 Everything on the periodic table are solids (black), except the
following:
 Hg and Br, which are liquids (dark blue)
 Diatomic molecules are gases, except Br (liquid) and Iodine
(solid)
 Noble gases are gases (light blue)
PRACTICE
 Using the Periodic Table to Determine States of Matter:
You have 2 minutes:
 Ti
 Br
 Ne
C
 Hg
S
Classifying the Elements
6.2
Reading the Periodic Table
Key Question
What information can be displayed in a periodic
table?
The symbols and names of the elements, along with
information about the structure of their atoms.
 Group 1A elements are called alkali metals
 Group 2A elements are called alkaline-earth metals
 Group 7A (nonmetals) are called halogens
Electron Configurations in Groups
Key Question
How can elements be classified based on electron
configurations?
Noble gases, representative elements, transition elements, or
inner transition metals
The Noble Gases
 Group 8A elements are called noble gases
 Sometimes called inert gases because they are stable and
rarely take part in a reaction
 The highest occupied energy level for each element is
completely filled with electrons; therefore, they are stable
The Representative Elements
 The elements in groups 1A-7A are called the
representative elements
 They display a wide range of properties
 These elements may be metals, nonmetals, or metalloids
 The s and p sublevels of the highest occupied energy level are
not filled
Transition Elements
 Transition metals are the group B elements that are usually
displayed in the main body of a periodic table
 The highest occupied s sublevel and a nearby d sublevel contain
electrons
 These elements are characterized by the presence of electrons in the
d orbitals
 Inner transition metals are the elements that appear below the
main body of the periodic table
 The highest occupied s sublevel and a nearby f sublevel generally
contains electrons
 They are characterized by the presence of electrons in the f orbitals
 Were once referred to as rare-earth metals, but was misleading
because some inner transition metals are more abundant than other
elements
Blocks of Elements
 The s block contains the elements in groups 1A and 2A, and the
noble gas helium
 The p block contains the elements in groups 3A-8A, except
helium
 The transition metal blocks belong to the d block
 One less than the period number
 The inner transition metals belong to the f block
 Two less than the period number
You are not required to know this way, but it wouldn’t hurt
to know how because its shorthand!
Periodic Trends
6.3
Trends in Atomic Size
 Atomic radius is one half the distance between the nuclei
of two atoms of the same elements when the atoms are
joined
Key Question
What are the trends among the elements for atomic
size?
Atomic size increases from top to bottom within a group, and
decreases from left to right across a period
Ions
 Ion is an atom or group of atoms that has a positive or negative
charge
 Atoms are electrically neutral because it has equal numbers of
protons and electrons
Key Question
How do ions form?
When electrons are transferred between atoms.
 An ion with a positive charge is called a cation
 An ion with a negative charge is called an anion
In Chapter 7, you will learn how ions are formed!
Trends in Ionization energy
 Ionization energy is the energy required to remove an
electron from an atom
Key Question
What are the trends among the elements for first
ionization energy?
Decrease from top to bottom within a group and increase from
left to right across a period.
Trends in Ionic Size
Key Question
What are the trends among the elements for ionic
size?
Increase from top to bottom within a group. Generally, the size
of cations and anions decrease from left to right across a
period.
Trends in Electronegativity
 Electronegativity is the ability of an atom of an element to
attract electrons when the atom is in a compound
Key Question
What are the trends among the elements for
electronegativity?
Values decrease from top to bottom within a group. For
representative elements, the values tend to increase from left
to right across a period.