Download - Chem chapt 6
The Periodic Table and Periodic Law
Chemistry Chapter 6
Main IdeasMain Ideas Periodic trends in the properties of atoms allow us
to predict physical and chemical properties.
The periodic table evolved over time as scientists discovered more useful ways to compare and organize elements.
Elements are organized into different blocks in the periodic table according to their electron configurations.
Trends among elements in the periodic table include their size and their ability to lose or attract electrons
Development of the Development of the Modern Periodic TableModern Periodic Table
Objectives:
Trace the development of the periodic table
Identify key features of the periodic table
Development of the Development of the Periodic TablePeriodic Table
In the 1700’s, Lavoisier compiled a list of all the known elements of the time. 33 elements
Development of the Development of the Periodic TablePeriodic Table
The 1800s brought large amounts of information and scientists needed a way to organize knowledge about elements.
Advent of electricity – break down compounds
Development of the spectrometer – identify newly isolated elements
Development of the Development of the Periodic TablePeriodic Table
The 1800s brought large amounts of information and scientists needed a way to organize knowledge about elements.
Industrial revolution – new chemistry based ingredients and compounds.
70 known elements by 1870
Development of the Development of the Periodic TablePeriodic Table
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.
Law of OctavesLaw of Octaves
Newlands (1864) noticed when the elements were arranged by increasing atomic mass, their properties repeated every eighth element.
Law of OctavesLaw of Octaves
Octaves was used due to the musical analogy, but was widely dismissed.
Some elements didn’t follow the pattern
The Periodic TableThe Periodic Table
Meyer and Mendeleev both demonstrated a connection between atomic mass and elemental properties.
The Periodic TableThe Periodic Table
Mendeleev’s Table – A Russian scientist – gets the most credit because he published first. Arranged elements by increasing mass
and columns with similar properties. Predicted the existence and properties
of undiscovered elements. Still some inconsistencies.
The Periodic TableThe Periodic Table
Moseley discovered that each element had a distinct number of protons. Once rearranged by increasing
atomic number, the table resulted in a clear periodic pattern.
The Periodic TableThe Periodic Table
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 Development of the Periodic TablePeriodic Table
The Modern Periodic The Modern Periodic TableTable
The modern periodic table contains boxes which contain the element's name, symbol, atomic number, and atomic mass.
The Modern Periodic The Modern Periodic TableTable
Rows of elements are called periods. (total of 7)
Columns of elements are called groups. (total of 18)
Elements in groups 1,2, and 13-18 possess a wide variety of chemical and physical properties and are called the representative elements.
Elements in groups 3-12 are known as the transition elements .
Types of ElementsTypes of ElementsElements are classified as metals, non-metals, and
metalloids.
Metals are made up of most of the representative elements and all of the transition elements. They are generally shiny when smooth and clean, solid
at room temperature, and good conductors of heat and electricity.
Most are Ductile and Malleable – Ductile – the ability to be drawn into wire. Malleable – the ability to be pounded into sheets
Types of ElementsTypes of ElementsElements are classified as metals,
non-metals, and metalloids.
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.
Types of ElementsTypes of Elements
The transition elements (groups 3 - 12) 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.
Lanthanides are phosphors – elements that emit light when struck by electrons.
The Modern Periodic The Modern Periodic TableTable
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 The Modern Periodic TableTable
Metalloids have physical and chemical properties of both metals and non-metals, such as silicon and germanium. They are found along the stair step of the table starting with Boron
QuestionsQuestions
What is a row of elements on the periodic table called? A. octave B. period C. group D. transition
QuestionsQuestions
What is silicon an example of? A. metal B. non-metal C. inner transition metal D. metalloid
Practice ProblemsPractice Problems Page 181 #1-7
Classification of the Classification of the ElementsElements
Objectives:
Explain why elements in the same group have similar properties.
Identify the four blocks of the periodic table on their electron configuration.
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
Electron configuration determines the chemical properties of an element.
Recall electrons in the highest principal energy level are called valence electrons.
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
All group 1 elements have one valence electron.
All group 2 elements have two valence electrons.
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration The energy level of an element’s valence
electrons indicates the period on the periodic table in which it is found.
The number of valence electrons for elements in groups 13-18 is ten less than their group number.
After the s-orbital is filled, valence electrons occupy the p-orbital.
Groups 13-18 contain elements with completely or partially filled p orbitals.
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
The d-block contains the transition metals and is the largest block. There are exceptions, but d-block elements
usually have filled outermost s orbital, and filled or partially filled d orbital.
The five d orbitals can hold 10 electrons, so the d-block spans ten groups on the periodic table.
Organizing the Organizing the Elements by Electron Elements by Electron
ConfigurationConfiguration
The f-block contains the inner transition metals. f-block elements have filled or partially filled
outermost s orbitals and filled or partially filled 4f and 5f orbitals.
The 7 f orbitals hold 14 electrons, and the inner transition metals span 14 groups.
Practice ProblemsPractice Problems
Page 186 #8-15
Periodic TrendsPeriodic Trends
Objectives:
Compare period and group trends of several properties.
Relate period and group trends in atomic radii to electron configuration
Atomic RadiusAtomic RadiusAtomic radius – is determined by the amount of
positive charge in the nucleus and the number of valence electrons of an atom. It is usually measured in picometers (10-12).
For metals, atomic radius is half the distance between adjacent nuclei in a crystal of the element.
For nonmetals, the atomic radius is the distance between nuclei of identical atoms.
Atomic RadiusAtomic Radius
Atomic RadiusAtomic Radius
The periodic trend: decreases from left to right (periods) and increases top to bottom (groups) due to the increasing positive charge in the nucleus.
Atomic RadiusAtomic Radius
Atomic RadiusAtomic Radius Atomic radius generally increases as you
move down a group.
The outermost orbital size increases down a group, making the atom larger.
Valence electrons are not shielded from the increasing nuclear charge because no additional electrons come between the nucleus and the valence electrons.
Ionic RadiusIonic RadiusIons – atom(s) that gain or lose one or more electrons
to form a net charge.
Ionic radius is the radius of a charged atom.
When atoms lose electrons and form positively charged ions, they always become smaller. Lost electrons are usually valence electrons and
could leave the outer orbital empty and therefore smaller.
Electrostatic repulsion between remaining electrons decreases and pulls closer to nucleus.
Ionic RadiusIonic Radius
When atoms gain electrons and forms a negatively charged ion, they become larger. Increased electrostatic repulsion
increases distance of outer electrons.
Ionic RadiusIonic RadiusPeriodic Trend: radius of an ion
decreases from left to right (periods) until charge changes and then the radii increases dramatically. After the change, the radius continues to decrease. Ionic radii increases top to bottom (groups) until change in charge.
Ionic RadiusIonic Radius
Ionization EnergyIonization EnergyIonization energy is the energy needed to
remove an electron from the positive charge of the nucleus of a gaseous atom. (how strongly a nucleus holds on to an electron.)
First ionization energy is the energy required to remove the first electron.
Removing the second electron requires more energy, and is called the second ionization energy.
Ionization EnergyIonization Energy Atoms with large ionization energies
have a strong hold of its electrons and are less likely to form positive ions.
Atoms with low ionization energies lose their outer electrons easily and readily form positive ions.
The ionization at which the large increase in energy occurs is related to the number of valence electrons.
Ionization EnergyIonization EnergyPeriodic Trend: 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 EnergyIonization Energy
The octet rule states that atoms tend to gain, lose or share 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.
Ionization EnergyIonization Energy
ElectronegativityElectronegativityElectronegativity of an element
indicates its relative ability to attract electrons in a chemical bond. Measured in Paulings: numbers 4 and less.
ElectronegativityElectronegativityPeriodic Trend: electronegativity decreases
down a group and increases left to right across a period.
QuestionsQuestions
The lowest ionization energy is the ____. A. first B. second C. third D. fourth
QuestionsQuestions
The ionic radius of a negative ion becomes larger when: A. moving up a group B. moving right to left across period C. moving down a group D. the ion loses electrons
Practice ProblemsPractice Problems Page 189 #16-19; Page 194 #20-23
Key ConceptsKey Concepts The elements were first organized by increasing
atomic mass, which led to inconsistencies. Later, they were organized by increasing atomic number.
The periodic law states that when the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties.
The periodic table organizes the elements into periods (rows) and groups (columns); elements with similar properties are in the same group.
Key ConceptsKey Concepts Elements are classified as either metals, nonmetals,
or metalloids.
The periodic table has four blocks (s, p, d, f). Elements within a group have similar chemical
properties. The group number for elements in groups 1 and 2
equals the element’s number of valence electrons. The energy level of an atom’s valence electrons
equals its period number.
Key ConceptsKey Concepts Atomic and ionic radii decrease from left to right across a
period, and increase as you move down a group.
Ionization energies generally increase from left to right across a period, and decrease as you move down a group.
The octet rule states that atoms gain, lose, or share electrons to acquire a full set of eight valence electrons.
Electronegativity generally increases from left to right across a period, and decreases as you move down a group.
Chapter QuestionsChapter Questions
The actinide series is part of the
A. s-block elements.
B. inner transition metals.
C. non-metals.
D. alkali metals.
Chapter QuestionsChapter Questions
In their elemental state, which group has a complete octet of valence electrons?
A. alkali metals
B. alkaline earth metals
C. halogens
D. noble gases
Chapter QuestionsChapter Questions
Which block contains the transition metals?
A. s-block
B. p-block
C. d-block
D. f-block
Chapter QuestionsChapter Questions
An element with a full octet has how many valence electrons?
A. two
B. six
C. eight
D. ten
Chapter QuestionsChapter Questions
How many groups of elements are there?
A. 8
B. 16
C. 18
D. 4
Chapter QuestionsChapter Questions
Which group of elements are the least reactive?
A. alkali metals
B. inner transition metals
C. halogens
D. noble gases
Chapter QuestionsChapter Questions
On the modern periodic table, alkaline earth metals are found only in ____.
A. group 1
B. s-block
C. p-block
D. groups 13–18
Chapter QuestionsChapter Questions
Bromine is a member of the A. noble gases. B. inner transition metals. C. earth metals. D. halogens.
Chapter QuestionsChapter Questions
How many groups does the d-block span?
A. two
B. six
C. ten
D. fourteen
THE END
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