Chapter 2:Unit 2. Features of Periodic Table

Periodic Table

Dmitri Mandeleev, a Russian Scientist, organized all the known elements according to atomic weight. He realized that certain properties of elements recur periodically, the table is known as Periodic Table.

In most Modern Periodic Table, elements are listed in order of increasing atomic number.

The vertical columns are assigned group numbers using two different numbering schemes I-VIII plus the letter A or B or 1-18.

The periodic table is divided into main group elements (Group 1A-8A) or representative elements, Transition metals (Group IB-8B) and the inner transition elements or rare earth elements are located in the two rows below the main table. Group IA, IIA are on the left hand side of the periodic table, group IIIA-VIIIA are on the right hand side of the periodic table. In between IIA and IIIA, group B elements or transition elements are present.

Elements that have similar physical chemical properties are grouped in columns called groups or families. Some of these groups have special names, for example group I-alkali metals, Group II-alkaline earth metal, halogens: second last column, and noble gases (the last column of elements).

Not only do the elements in any particular column of the periodic table share similar properties, properties can also vary in some similar away down the column or across the period. For example: elements Fluorine (atomic number 9), chlorine (atomic number 17), Bromine ( atomic number 35) and Iodine ( atomic number 53) all fall in the under the same column on periodic table. They are all colorful substances and the color gets deeper down the group. This group of elements is called halogen. Boiling points of halogens regularly increase down the group.

Each row of elements on the Periodic table is called a period. Periods have different lengths.

There are three classes of elements, metals, nonmetals and metalloids. The majority of element are metals. Metals are shiny materials that are good conductor of heat and electricity. All metals are solids at room temperature except Hg (liquid). Metals have malleable and ductile property.

Nonmetals do not have a shiny appearance and they are generally poor conductor of heat and electricity. They can be solid (Carbon, sulfur), liquid (Bromine) or gas (Nitrogen, oxygen). With the exception to the hydrogen, they appear to the right side of the periodic table.

The Periodic table contains a step line from Boron to Astatine. All metals are located to the left of the line. All nonmetals except Hydrogen are located to the right of the line. The eight elements located along the line are metalloids. Metalloids have properties intermediate between metals and nonmetals. Eight elements that are categorized as metalloids: Boron, Silicon, Aresinic, Germanium, Antimony, Tellurium, Polonium(Po) and Astatine(At).

Each box on the periodic table represents one element. For example in the diagram below, the  element hydrogen is represented by its symbol H, atomic number 1 and atomic weight 1.008 amu.

Below is an example of how melting and boiling point change acoross the period or down the group.

Below please find  complete description of the modern Periodic Table.

Here is the magnified view of the one of the boxes of periodic table and their meaning.

Interactive simulation on Periodic Table:

TRY THIS OUT!

Activity: Click on each element on the above simulation site and get information about that element. For example click on 1) Hg, 2) Cs and 3) He, which one is solid, liquid and gas?

Also, look at the color classification of the metals, nonmetals and metalloids. Can you name one transition metal, one nonmetal solid and one Nobel gas?

Here are some examples of elements from periodic table:

                                                                                              Boron

Bismuth

The following activity has been taken from AACT

Periodic table puzzle

Lucky Seven

Directions

First, use the periodic table and the clues provided below to determine the seven element names that are hidden in the puzzle below. Then try to find the letters of each of the element names in the puzzle. The names are organized in circles, with one letter from the name placed in the center of the circle and the rest of the letters surrounding it.

Note: The letters may not be organized in the order that they appear in the name! An example for Lithium is shown below for reference:

Clues

1. This toxic element is a metalloid found in the 4^th ______________
2. This metal is slightly heavier than potassium, and readily gives up two electrons to form bonds with non-metals. _____________
3. This element has 92 protons and is located in the Actinide series. ______________
4. This metalloid has the same number of valence electrons as carbon, and is approximately double the mass of nitrogen. _________________
5. This transition metal is commonly known as Quicksilver, and is the only metal that exists as a liquid at standard temperature and pressure. ______________
6. This noble gas is heavier than 35 other elements on the periodic table. __________
7. This very reactive halogen is more than double the mass of the halogen that is located in the period before it. ______________

Answer Key: Lucky Seven

Directions

First, use the periodic table and the clues provided below to determine the seven element names that are hidden in the puzzle below. Then try to find the letters of each of the element names in the puzzle. The names are organized in circles, with one letter from the name placed in the center of the circle and the rest of the letters surrounding it.

Note: The letters may not be organized in the order that they appear in the name!

Clues

1. This toxic element is a metalloid found in the 4^th Arsenic

2. This metal is slightly heavier than potassium, and readily gives up two electrons to form bonds with non-metals. Calcium

3. This element has 92 protons and is located in the Actinide series. Uranium

4. This metalloid has the same number of valence electrons as carbon, and is approximately double the mass of nitrogen. Silicon

5. This transition metal is commonly known as Quicksilver, and is the only metal that exists as a liquid at standard temperature and pressure. Mercury

6. This noble gas is heavier than 35 other elements on the periodic table. Krypton

7. This very reactive halogen is more than double the mass of the halogen that is located in the period before it. Bromine

Questions:

1. Identify the following elements in the periodic table and give 1) element’s name and symbol, 2) any special name, 3) classification (transition, rare earth, main group etc.)

a) Period 4, group 1A
b) Period 3, group 8A
c) Period 5, group 12

2. Write metals, nonmetals or metalloids to match the following:
   a) Ductile:
   b) Poor conductor of heat and electricity:
   c) Only eight elements of periodic table:

Ans: 1. a) Potassium K, metals, alkali metal
b) Argon Ar, nonmetal, noble gas
c) Cadmium Cd, metal, Transition metal

2. a) ) metal
b) nonmetal
c)metalloids