0.5 The best table in the world  (Page 5/3)

The best table in the world!

Objective

The goals of this experiment are:

• to observe the reactions of several metals with cold water, hot water, acids and then other metal ions.
• to prepare an activity series of the metals based on the observations from the above reactions.

Grading

You will be assessed on:

• observations of the reactions of several metals with cold water, hot water, acids and then other metal ions.
• preparation of an activity series of the metals based on the observations from the above reactions.
• answers to the post-lab questions.

Background information

First, you are going to travel back to 1869 and marvel at how the first periodic law and table were born when only 63 elements had been discovered at the time. A 35 year old professor of general chemistry, Dmitri Ivanovich Mendeleev at the University of St. Petersburg (now Lennigrad) in Russia was shuffling his cards with the properties of each element on each card trying to organize his thoughts for his soon-to-be famous textbook on chemistry. When he realized that if the elements were arranged in the order of their atomic weights, there was a trend in properties that repeated itself several times! His paper was delivered by his graduate student, Nikolai Aleksandrivich Menchutkin before the Russian Chemical Society while Medeleev was busy visiting cheesemaking cooperatives at the time!

In order to see and find order among the elements, we must have some general acquaintance with them. Elements are made of matter, and matter is defined as anything that has mass and occupies space. This includes everything that you can see and a lot that you cannot. It follows that in order to distinguish between different types of matter (in other words different elements) we have to assess their properties.

There are two types of properties: intensive and extensive. In the former case, intensive properties do not depend on the how much of an element is present but do include state (whether a substance is a solid, liquid or gas), color and chemical reactivity. Extensive properties depend on the quantity of matter present - mass and volume are extensive properties.

Properties can be further categorized as either chemical or physical. A chemical change describes how the substance may change composition, such as spontaneously by combustion or in combination with other substances. On the other hand, physical changes are those properties that can be measured without changing the composition of the matter. Condensation of steam to water is a physical change.

Introduction

What is there to know about the periodic table? Why is it important? Why does it appear in nearly every science lecture room and labs? Is it just a portrait of an aspect of chemistry or does it serve a useful purpose? Why is the name periodic appropriate? Why is the table arranged in such a way? What are the important features of the table? Does it give order to the approximately 120 known elements?

Relative reactivity of metals and the activity series

 A superficial glance at the Periodic Table will reveal that all known elements are listed by their chemical symbols. An in depth glance at the Periodic Table yields information on the mass of an atom of the element in atomic mass units (amu) for the molar mass of a mole ( $6\text{.}\text{02}\times {\text{10}}^{\text{23}}$ ) of atoms in grams below the chemical symbol for each element. Above the chemical symbol for each element, there is a second number listed, the atomic number, which gives the number of protons (positively charged particles in the nucleus), or the number of electrons (negatively charged outside the nucleus) for a neutral atom.