The Periodic TableKarlene Bisnott

February 10, 2009

Students should be familiar with the concept of the atom as the basic building block of matter.

Students should be able to: Explain the basis of the arrangement of

elements in the periodic table Identify trends in Period 3 using gradation

from metallic to non- metallic properties

Overview

Identify trends in Group II Identify trends in Group VII Predict properties of unknown elements

based on group trends Identify metals and non-metals in the

Periodic Table Define metallic bonding Define covalent bonding

Overview cont’d

Define giant molecular crystals Explain the term allotropy

Overview cont’d

In groups of four or five, students will be asked to sequence a deck of cards in rows and columns.

They will then discuss their arrangements.

Introductory Activity A historical

background of the Periodic Table

This was developed by Dimitri Mendeleev in 1869.

Elements were arranged into rows and columns.

We are going to construct our own table. Step 1: Place the atoms in ascending order

using the number of protons Step 2: Arrange them in eight columns and

three rows. Step 3:Atoms with only one electron in the

outer shell are placed on the left. Step 4: Atoms with a filled shell are placed

on the right.

Constructing a Periodic Table

Your constructed table should look like this: http://www.chem.iastate.edu/group/Greenbo

we/sections/projectfolder/flashfiles/reaction/bonding1.swf

The Resulting Table

Elements found to the left of the table are called metals.

They react by losing electrons from their valence shells to obtain a full outer shell.

Elements found from the middle to the right of the table are called non-metals.

They react by either gaining electrons or sharing electrons to obtain a full outer shell.

Metals and Non-metals

Let us take a closer look at the Periodic Table

http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/reaction/bonding1.swf

The metals are located to the left. The non-metals are located from the middle

to the right.

A closer look

The vertical columns in the periodic table are called groups.

The elements in each group have similar properties.

The chief similarity is the fact that they have the same number of electrons in the outer shell. http://www.teachnet.ie/tburke/periodic/element/html

 

Groups

Look at this periodic table http://www.teachnet.ie/tburke/periodic/

element/html Each group of elements is assigned a name. Give the names assigned to Groups I, II,VII

and 0. List the elements found in Group II and

Group VII.

Practice Exercises

The horizontal rows of elements in the Periodic Table are called periods. For the first twenty elements, there are four periods.

The elements in each period have properties that are similar.

The chief similarity is the number of shells in the atom.

Periods

Let us take a closer look at the periods. http://www.teachnet.ie/tburke/periodic/

element/html The elements in the same period have the

same number of shells of electrons. 

Example

Look at the periodic table. List the elements found in Period 3, stating

how many electrons are in the outer shell.

Practice Exercises

Let us examine how the following vary down group II and group VII

Atomic size Ease of ionization Melting points Boiling points Density

Trends down the Groups http://www.learners

tv.com/animation/animation.php?ani=184&cat=chemistry

Let us examine how the following vary across Period 3:

Atomic size Electronegativity Electropositivity Conductivity Melting points

Trends across the Period http://www.chem.ia

state.edu/group/Greenbowe/sections/projectfolder/flashfiles/reaction/bonding1.swf

Create a table to show how the following vary across Period 3: Melting point, conductivity, atomic size, electronegativity, electropositivity

Create a table showing how the following vary down Group II: atomic size, density, melting point, boiling point, ease of ionization.

Create a similar table for Group VII

Practice Exercises

This type of bonding is found in metals. The atoms in metals are packed so tightly that the electrons on the outer shell are knocked off. These free electrons form a ‘sea’ around the nuclei. An attraction occurs between the positive nuclei and the negative sea of electrons. This attraction is called metallic bonding.

Metallic bonding

Here is a diagram showing the bonding in metals.

Metallic Bonding cont’d

Non-metals form covalent bonds. This type of bond is formed when carbon

atoms bond with each other. Two structures formed are:

Graphite and diamond. Click on the link to observe these

structures.

Giant Molecular Crystals

Allotropes are different structures of the same element.

Therefore carbon has two allotropes: Diamond and graphite

Allotropes

Elements are arranged logically in a table. This arrangement of elements in ascending

order of atomic number is called a Periodic Table.

The elements are organized into families called groups and periods.

The elements in each family have similar properties.

Summary

The elements in the Periodic Table can be classified as metals and non-metals.

The bonding found in metals is called metallic bonding.

The bonding found in non-metals is called covalent bonding.

The non-metals can form simple molecules or giant molecular crystals.

Summary cont’d

Different structures of the same element are called allotropes.

The Periodic Table provides a wealth of information about the elements.

Summary cont’d

http://chemistry.about.com/od/testsquizzes/l/bltrendsquiz.htm

Click on the link above to try this quiz on the Periodic Table.

Review/Quiz

Ferguson & Hart: CXC Chemistry, Oxford University Press, 1994

 Gallagher & Ingram: Complete Chemistry, Oxford University Press, 1997

 Tindale Anne : Chemistry – A Concise Revision Course for CXC, Stanley Thornes (Publishers) Ltd., 1998

 The Internet

Resources