The Periodic Law Describe the arrangement of elements in the modern periodic table




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TitleThe Periodic Law Describe the arrangement of elements in the modern periodic table
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  • The Periodic Law

  • Describe the arrangement of elements in the modern periodic table

  • Understand the trends that established the modern periodic table

  • Locate periods and groups in the period table

  • Dmitri Medeleev gave us a functional scheme with which to classify elements.

  • Mendeleev’s scheme was based on chemical properties of the elements.

  • It was noticed that the chemical properties of elements increased in a periodic manner.

  • The periodicity of the elements was demonstrated by Medeleev when he used the table to predict to occurrence and chemical properties of elements which had not yet been discovered.

  • Mendeleev left blank spaces in his table when the properties of the elements above and below did not seem to match. The existence of unknown elements was predicted by Mendeleev on the basis of the blank spaces. When the unknown elements were discovered, it was found that Mendeleev had closely predicted the properties of the elements as well as their discovery.

  • The Periodic Law

  • Similar physical and chemical properties recur periodically when the elements are listed in order of increasing atomic number.

The History of the Modern Periodic Table

During the nineteenth century, chemists began to categorize the elements according to similarities in their physical and chemical properties. The end result of these studies was our modern periodic table.

Johann Dobereiner

John Newlands

John Newlands

John Newlands

Dmitri Mendeleev

ORIGINAL PERIODIC TABLE

  • 1. Developed by Dimitri Mendeleev in 1869 (Russian chemist)

  • 2. He arranged the elements by simila properties and increasing atomic mass.

Modern Periodic Table

  • 1. Elements arranged by increasing atomic #.

  • 2. Periodic Law: there is a periodic repetition of properties of the elements when they are arranged by increasing atomic #.

  • Mendeleev’s arrangement of the elements were presented to the Russian Physico-chemical Society by Professor Menschutkin because Mendeleev was ill.

  • The table was first published in the German chemistry periodical, Zeitschrift fϋr Chemie, in 1869.

Lothar Meyer

Elements known at this time

  • Both Mendeleev and Meyer arranged the elements in order of increasing atomic mass.

  • Both left vacant spaces where unknown elements should fit.

Henry Moseley

Henry Moseley

Glenn T. Seaborg

Glenn T. Seaborg

Periodic Table Geography—
Why is a periodic table useful?


Organizing the Elements

  • In a self-service store, the products are grouped according to similar characteristics. With a logical classification system, finding and comparing products is easy. You will learn how elements are arranged in the periodic table and what that arrangement reveals about the elements.

Searching For an Organizing Principle

-How did chemists begin to organize the known elements?
  • Chlorine, bromine, and iodine have very similar chemical properties.

  • A periodic table is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties.

  • A periodic table allows you to easily compare the properties of one element (or a group of elements) to another element (or group of elements).


Families of the Periodic Table

  • Families/Groups

Alkali metals

Alkali Earth metals

Boron Family

Carbon Family

Nitrogen Family

Oxygen

Transition Metals

Halogens

Noble Gases

Alkali Metals

  • Definition

- highly reactive metallic elements in group 1

- react with water to form hydrogen and alkaline solutions; burn in air

- al-quili means wood ashes

- term dates back to ancient times; people discovered that wood ashes mix with water to produce slippery solutions that can remove grease

- one outer electron, by losing this electron they become a cation, and become stable

Alkali Metals.

- soft metals; can be cut with a knife

- shiny, but dull quickly due to oxygen and water in air

- good conductors

- gaseous states at high temperatures become plasmas

ex. Na, Cs, Rb

Alkali-Earth Metals

  • Definition

- group 2 elements

- comes from idea of “Earth”, materials unable to light on fire

- reactive metallic elements with two electrons in the outermost energy level

- harder, denser, stronger and have higher melting points, lower reactivity than alkali

ex. Be, Ca, Mg

Transition Metals

  • Lanthanides

- shiny, metallic transition metals (58 – 71) in which electrons are added to 4f orbitals

- located at the bottom of the periodic table for convenience

  • Actinides

  • shiny metallic transition metals (90 – 103) in which electrons are added to 5f orbitals

  • located at the bottom of the periodic table for convenience

  • radioactive

Halogens

  • Definition

- nonmetallic elements in group 17, that have 7 electrons in the outer most energy level and combines with many metals to form salts

- term comes from Greek means salt former

Salt: a compound composed of positive and negative ions arranged in a regular 3D pattern

- most reactive group of nonmetals

- varying physical properties, similar chemical properties

Noble Gas

  • Definition

- elements in group 18 that are characterized by low reactivity

- term comes from noble people, did not associate with anyone other then their kind

- characterized by an octet of electrons in the outermost energy level; (happy)

- exception of helium

- very stable, (unreactive)

- colorless, odorless

- practical applications: balloons, illumination

Hydrogen

  • most common element in the universe

  • behaves unlike any other element due to its structure of 1 p 1 e

  • react with numerous elements

  • component of all hydrocarbons, and molecules that are essential to life; fats, proteins, carbohydrates

  • practical uses

ex. ammonia, fertilizers

Each horizontal row of the periodic table is called a period . Within a given period, the properties of the elements vary as you move across it from element to element

  • A Period

Each vertical column of the periodic table is called a group, or family.
Elements within a group have similar chemical and physical properties.

  • A Group or Family

Periodic Law

Metals, Nonmetals, and Metalloids

  • Metals, Metalloids, and Nonmetals in the Periodic Table

Each horizontal row of the periodic table is called a period . Within a given period, the properties of the elements vary as you move across it from element to element

  • A Period

Each vertical column of the periodic table is called a group, or family.
Elements within a group have similar chemical and physical properties.

  • A Group or Family

Alkali Metals

Alkaline Earth Metals

Transition Metals

InnerTransition Metals

Metals, Nonmetals, and Metalloids

  • Metals, Nonmetals, and Metalloids

  • What are three broad classes of elements?

Metals, Nonmetals, and Metalloids

  • Three classes of elements are metals, nonmetals, and metalloids.

  • Across a period, the properties of elements become less metallic and more nonmetallic.

Metals, Nonmetals, and Metalloids

  • Nonmetals

  • 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

  • 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.

Halogens

Noble Gases

The s and p block elements
are called
REPRESENTATIVE ELEMENTS.

  • The Modern Periodic Table

  • 1st

  • The periodic table is made up of rows of elements and columns.

  • An element is identified by its chemical symbol.

  • The number above the symbol is the atomic number

  • The number below the symbol is the rounded atomic weight of the element.

  • A row is called a period

  • A column is called a group

  • (A) Periods of the periodic table, and (B) groups of the periodic table.

  • Periodic Patterns

  • The chemical behavior of elements is determined by its electron configuration

  • Energy levels are quantized so roughly correspond to layers of electrons around the nucleus.

  • A shell is all the electrons with the same value of n.

  • n is a row in the periodic table.

  • Each period begins with a new outer electron shell

  • Each period ends with a completely filled outer shell that has the maximum number of electrons for that shell.

  • The number identifying the A families identifies the number of electrons in the outer shell, except helium

  • The outer shell electrons are responsible for chemical reactions.

  • Group A elements are called representative elements

  • Group B elements are called transition elements.

Families

  • Chemical “Families”

  • IA are called alkali metals because the react with water to from an alkaline solution

  • Group IIA are called the alkali earth metals because they are reactive, but not as reactive as Group IA.

  • They are also soft metals like Earth.

  • Group VIIA are the halogens

  • These need only one electron to fill their outer shell

  • They are very reactive.

  • Group VIIIA are the noble gases as they have completely filled outer shells

  • They are almost non reactive.

  • Four chemical families of the periodic table: the alkali metals (IA), the alkaline earth metals (IIA), halogens (VII), and the noble gases (VIIIA).

The Periodic Table—A Preview

  • The Periodic Table

6.1 Section Quiz

  • 1. The modern periodic table has elements arranged in order of

  • colors.

  • melting and boiling points.

  • increasing atomic mass.

  • increasing atomic number.

6.1 Section Quiz

  • 2. Mendeleev arranged the elements in his periodic table in order of increasing

  • atomic number.

  • number of protons.

  • number of electrons.

  • atomic mass

6.1 Section Quiz

  • 3. Which one of the following is NOT a general property of metals?

  • ductility

  • malleability

  • having a high luster

  • poor conductor of heat and electricity

Classifying the Elements

  • A coin may contain much information in a small space—its value, the year it was minted, and its country of origin. Each square in a periodic table also contains information. You will learn what types of information are usually listed in a periodic table. 3rd

Squares in the Periodic Table

  • Squares in the Periodic Table

  • What type of information can be displayed in a periodic table?

Squares in the Periodic Table

  • The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms.

Squares in the Periodic Table

  • The background colors in the squares are used to distinguish groups of elements.

  • The Group 1A elements are called alkali metals.
  • The Group 2A elements are called alkaline earth metals.
  • The nonmetals of Group 7A are called halogens.

Squares in the Periodic Table

Electron Configurations in Groups

  • Electron Configurations in Groups

  • How can elements be classified based on their electron configurations?

  • Elements can be sorted into noble gases, representative elements, transition metals, or inner transition metals based on their electron configurations

Electron Configurations in Groups

  • The blimp contains helium, one of the noble gases.

Electron Configurations in Groups

  • The Noble Gases

  • The noble gases are the elements in Group 8A of the periodic table. The electron configurations for the first four noble gases in Group 8A are listed below.

Electron Configurations in Groups

  • The Representative Elements

  • Elements in groups 1A through 7A are often referred to as representative elements because they display a wide range of physical and chemical properties.

  • The s and p sublevels of the highest occupied energy level are not filled.
  • The group number equals the number of electrons in the highest occupied energy level.

Electron Configurations in Groups

  • In atoms of the Group 1A elements below, there is only one electron in the highest occupied energy level.

Electron Configurations in Groups

  • In atoms of the Group 4A elements below, there are four electrons in the highest occupied energy level.

Representative Elements

  • Representative Elements

Transition Elements

  • Transition Elements

  • There are two types of transition elements—transition metals and inner transition metals. They are classified based on their electron configurations.

  • In atoms of a transition metal, the highest occupied s sublevel and a nearby d sublevel contain electrons.

  • In atoms of an inner transition metal, the highest occupied s sublevel and a nearby f sublevel generally contain electrons.

Transition Elements

  • Blocks of Elements

6.2 Section Quiz

  • 1. Which of the following information about elements is usually NOT included in a periodic table?

  • color

  • symbol

  • atomic number

  • atomic mass

6.2 Section Quiz

  • 2. An alkali metal would have in the highest occupied energy level

  • an s2 electron.

  • an s1 electron.

  • p2 electrons.

  • p6 electrons.

6.2 Section Quiz

  • 3. Which one of the following is incorrectly labeled?

  • Ne, noble gas

  • Cu, transition metal

  • Ga, transition metal

  • Cl, halogen

6.2 Section Quiz

  • 4. Transition metals are characterized as being different than representative elements because they have electrons in which suborbitals?

  • p

  • d

  • s

  • f

Periodic Trends

  • Sodium chloride (table salt) produced the geometric pattern in the photograph. Such a pattern can be used to calculate the position of nuclei in a solid. You will learn how properties such as atomic size are related to the location of elements in the periodic table.

  • Trends in Atomic Size

  • What are the trends among the elements for atomic size?

  • The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined.

Trends in Atomic Size

Trends in Atomic Size

  • Atomic Radii:

- half the distance between the nuclei of the same atoms bonded together

Trends of the Atomic Radii

- at certain intervals, atomic radii is dramatically greater than that of the previous element

  • Ionization energy:

- amount of energy required to pull an electron away from an atom to form a positively charged ion

- generally increases with increasing atomic number

- at some points, when atomic number increases there is a dramatic decrease

ex. Li, Na, K, Rb, Cs, Fr

Trends of Ionization Energy

Trends in Ionization Energy

  • What are the trends among the elements for first ionization energy, ionic size, and electronegativity?

  • The energy required to remove an electron from an atom is called ionization energy.

  • The energy required to remove the first electron from an atom is called the first ionization energy.

  • The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy.

Trends in Ionization Energy

  • The energy required to remove an electron from an atom is called ionization energy.

  • The energy required to remove the first electron from an atom is called the first ionization energy.
  • The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy.

Trends in Ionization Energy

  • Group and Periodic Trends in Ionization Energy

  • First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.

Trends in Ionization Energy

Trends in Ionic Size

  • Trends in Ionic Size

  • During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form.

  • Cations are always smaller than the atoms from which they form. Anions are always larger than the atoms from which they form

Trends in Ionic Size

  • Relative Sizes of Some Atoms and Ions

Trends in Ionic Size

  • Trends in Ionic Size

  • Trends in Electronegativity

  • Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound.

  • In general, 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.

  • Representative Elements in Groups 1A through 7A

Results of Organization

7 periods (Across)

- Atomic Radius decreases

- Ionization energy increase

- Electron Affinity increases

18 Groups (Down)

- Atomic Radius increases

- Ionization energy decreases

- Electron affinity decreases

- Elements have similar chemical and physical properties

- # of valence electrons are the same

6.3 Section Quiz

  • 1. Which of the following sequences is correct for atomic size?

  • Mg > Al > S

  • Li > Na > K

  • F > N > B

  • F > Cl > Br

6.3 Section Quiz

  • 2. Metals tend to

  • gain electrons to form cations.

  • gain electrons to form anions.

  • lose electrons to form anions.

  • lose electrons to form cations.

6.3 Section Quiz

  • 3. Which of the following is the most electronegative?

  • Cl

  • Se

  • Na

  • I

END OF SHOW


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