The Periodic Table

The Periodic Table

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Objectives

• Explain the roles of Mendeleev and Moseley in the development of the periodic table.

  
  

  •Describe the modern periodic table.

  
  

  
  

Mendeleev and Chemical Periodicity 

• Mendeleev noticed that when the elements were arranged in order of increasing atomic mass, certain similarities in their chemical properties appeared at regular intervals.

  
  

  •Repeating patterns are referred to as periodic.

  
  

  •Mendeleev created a table in which elements with similar properties were grouped together—a periodic table of the elements.

Mendeleev and Chemical Periodicity 

• After Mendeleev placed all the known elements in his periodic table, several empty spaces were left.

  
  

  •In 1871 Mendeleev predicted the existence and properties of elements that would fill three of the spaces.

  
  

  •By 1886, all three of these elements had

  been discovered.

Moseley and the Periodic Law 

• In 1911, the English scientist Henry Moseley discovered that the elements fit into patterns better when they were arranged according to atomic number, rather than atomic weight.

  
  

  •The Periodic Law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.

Multiple Choice

Mendeleev arranged the elements by increasing

• number

• mass

• theory

Multiple Choice

A few elements were out of place on Mendeleev’s periodic table. For question two, name the scientist who put them in the right place?

• Mendeleev

• Democritus

• Moseley

• Dalton

The Modern Periodic Table 

The Periodic Table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group.

Multiple Choice

Elements on the modern periodic table are arranged in order of increasing

• atomic number

• boiling point

• atomic symbol

• atomic mass

Multiple Choice

Which element has the largest atomic number?

• Na

• K

• Li

• Rb

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

Metals, nonmetals, and metalloids.

• Metals are generally malleable, ductile, and good conductors of heat and electric current.

• Most nonmetals are brittle, poor conductors of heat and electric current. Many are gases at room temp.

• A metalloid generally has properties that are similar to those of metals and nonmetals.

Multiple Choice

Is oxygen a metal, nonmental, or metalloid?

• metal

• nonmetal

• metalloid

Info on the PT

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

• Black letters are solid elements, red letters are gases, blue letters are liquids and white or gray letters are not found in nature.

• 
  

Multiple Choice

What phase of matter is oxygen at room temperature?

• solid

• liquid

• gas

• plasma

Objectives

• Explain the relationship between electrons in energy levels and the length of each period of the periodic table.

• Locate and name the four blocks of the periodic table.

• Describe the locations in the periodic table and the general properties of the alkali metals, the alkaline-earth metals, the halogens, and the noble gases.

Periods, Groups and Blocks of the Periodic Table 

• Elements are arranged vertically in the periodic table in groups (1-18) that share similar chemical properties because they have the same amount of valence electrons.

• Chemical properties are determined by the number of electrons in an atom.

• Elements are also organized horizontally in rows, or periods (1-7).

• The length of each period is determined by the number of electrons that can occupy the sublevels being filled in that period.

Groups 1,2 13-18 are also called, 1A-8A the group number in this format tells you the amount of valence electrons

Multiple Choice

What is it about the elements in a column of the periodic table that makes them behave similarly?

• Atomic number

• Atomic mass

• Electron configuration

Multiple Choice

What period and group on the periodic table is calcium in?

• period 3, group 16

• period 4, group 2

• period 1, group 11

• period 6, group 7

Multiple Choice

What is the atomic number for the element in period 3, group 16?

• 16

• 32

• 8

• 18

Multiple Choice

How many valence electrons does an atom of oxygen have?

• 4

• 5

• 6

• 7

Multiple Choice

How many energy levels does an atom of oxygen have?

• 1

• 2

• 3

• 4

Periods and Blocks of the Periodic Table 

The periodic table is divided into four blocks, the s, p, d, and f blocks. The name of each block is determined by the electron sublevel being filled in that block

Groups of the Periodic Table

• The elements of Group 1 of the periodic table are known as the alkali metals. 

• lithium, sodium, potassium, rubidium, cesium, and francium

• In their pure state, all of the alkali metals have a silvery appearance and are soft enough to cut with a knife.

• They are highly reactive

• 1 valence electron

Groups of the Periodic Table

• The elements of Group 2 of the periodic table are called the alkaline-earth metals.

• beryllium, magnesium, calcium, strontium, barium, and radium

• Group 2 metals are less reactive than the alkali metals, but are still too reactive to be found in nature in pure form.

• 2 valence electrons

Groups of the Periodic Table

• The elements of Group 3-12 of the periodic table are called the transition metals.

• copper, iron, gold, titanium, iron, etc.

• Transition metals are shiny, good conductors of electricity, are less reactive than alkali metals and have high melting points

Groups of the Periodic Table

• The elements of Group 17 of the periodic table are called the halogens.

• Fluorine, Chlorine, Bromine, Iodine, & Astatine.

• Halogens can be gaseous, liquid, or solid at room temperature.

• Halogens are highly reactive nonmetals and react strongly with alkali metals.

• 7 valence electrons

Groups of the Periodic Table

• The elements of Group 18 of the periodic table are called the noble gases.

• Helium, Neon, Argon, Krypton, Xenon, & Radon.

• Gases at room temperature.

• These nonmetals are sometimes called the inert gases because they rarely take part in a reaction

• 8 valence electrons, except He that has 2

Groups of the Periodic Table

Lanthanides are metals that quickly dissolve in acid, ignite in air, and reacts with halogens, sulfur, 

hydrogen, carbon, and nitrogen upon heating

Groups of the Periodic Table

Actinides are metals that are mostly man-made in particle accelerators, many are radioactive and react with air.

Multiple Choice

To which group on the periodic table does sodium belong?

• alkali metals

• alkaline earth metals

• halogen

• transition metals

• noble gases

Multiple Choice

To which group on the periodic table does iodine belong?

• alkali metals

• alkaline earth metals

• halogen

• transition metals

• noble gases

Multiple Choice

To which group on the periodic table does neon belong?

• alkali metals

• alkaline earth metals

• halogen

• transition metals

• noble gases

Multiple Choice

To which group on the periodic table does iron belong?

• alkali metals

• alkaline earth metals

• halogen

• transition metals

• noble gases

Multiple Choice

To which group on the periodic table does calcium belong?

• alkali metals

• alkaline earth metals

• halogen

• transition metals

• noble gases

Periodic Trends Definitions

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

• ionization energy: the energy required to remove an electron from an atom in its gaseous state

• electronegativity: the ability of an atom to attract electrons when the atom is in a compound

Electrons and the Structure of Atoms

• Atomic size, ionization energy, ionic size, and electronegativity are trends that vary across periods and groups of the periodic table.

• These trends can be explained by variations in atomic structure.

• The increase in nuclear charge within groups and across periods explains many trends.

• Within groups, an increase in electron shielding has a significant effect on these trends.

Multiple Choice

Which element has the largest electronegativity?

• C

• N

• O

• F

Multiple Choice

Which element has the largest ionization energy?

• I

• F

• Cl

• Br

Multiple Choice

Which element has the largest atomic radius?

• C

• N

• O

• F