Pp%2c atom%2c physical and chemical changes

INTRODUCTION

The measurement of a physical property maychange the arrangement of matter in a sample,but not the structure of its molecules. In otherwords, a physical property may involvea physical change, but not a chemicalchange.Examples of physical properties includemass, density, color, boiling point, temperature,and volume.

DEFINITION PHYSICAL PROPERTIES

DEFINITION CHEMICAL PROPERTIES

Chemical change

occur when a substance combines with another to

form a new substance, called synthesis or,

alternatively, decomposes into two or more different

substances. These processes are called chemical

reactions and, in general, are not reversible except by

further chemical reactions.

Condesation apparatus

In a laboratory a condenser is a piece of laboratory glassware used to cool hot vapors or liquids. [1] A condenser usually consists of a large glass tubecontaining a smaller glass tube running its entire length, within which the hot fluids pass.The ends of the inner glass tube are usually fitted with ground glass joints which are easily fitted with other glassware. During reflux, the upper end is usually left open to the atmosphere or vented through a bubbler or a drying tube to prevent the ingress of water or oxygen.[2]

WHAT IS A ATOM?

• A unit of matter, the smallest unit of an element, consisting of a dense, central, positively charged nucleus surrounded by a system of electrons, equal in number to the number of nuclear protons

HISTORY…• the study of the atomic nature of matter

illustrates the thinking process that goes on in the philosophers and scientists heads. The models they use do not provide an absolute understanding of the atom but only a way of abstracting so that they can make useful predictions about them. The epistemological methods that scientists use provide us with the best known way of arriving at useful science and factual knowledge. No other method has yet proven as successful.Actually, the thought about electricity came before atoms.

• In about 600 B.C. Thales of Miletus discovered that a piece of amber, after rubbing it with fur, attracts bits of hair and feathers and other light objects. He suggested that this mysterious force came from the amber. Thales, however, did not connect this force with any atomic particle.

ATOM MODEL