Part 2 Chapter 1 Chemistry

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The book goes into another section called States of Matter. (Again ' ' are used to show the wors being defined.)It says, "Matter occurs in three states: solid, liquid, and gas. A 'solid' has both a definite size and shape. A 'liquid' has a definite volume but takes the shape of the container, and a 'gas' has neither a definite shape nor a definite volume. These states of matter can often be changed by the addition of heat energy. An example of this is ice changing to liquid water and finally to steam." The next section deals with the Composition of Matter. "Matter can be subdivided into two general categories: distinct (pure) substances and mixtures. Distinct substances are substances that can be subdivided into the smallest particle that still has the properties of the substance. At that point, if the substance is made up of only one kind of atom. it is called an 'element.' Atoms are considered to be the basic building blocks of matter that cannot be easily created or destroyed. The word "atom" comes from the Greek and means the smallest possible piece of something. Today there are approximately 109 different kinds of atoms, each with its own unique composition. These atoms then are the building blocks of elements when only one kind of atom makes up the substance. If, however, there are two or more kinds of atoms joined together in definite grouping, this distinct substance is called a 'compound.' Compounds are made by combining elements in a definite proportion (or ratio) by mass and are made up of two or more kinds of atoms. This is called the 'Law of Definite composition (or Proportions).' The smallest natural occurring unit of a compound is called a "molecule" of that compound. A molecule of a compound has a definite shape that is determined by how the atoms are bonded to or combine with each other" described in Chapter 3. " An example is the compound water: it always occurs in a two hydrogen atoms to one oxygen atom relationship. 'Mixtures', however, can vary in their composition." Grandma will go into it more in the next lesson.