Matter and life

Matter and life

DEFINITION AND INTRODUCTION

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Matter is anything that has mass. All objects around us are made of matter.  Matter can be defined as a “material substance that occupies space, has mass and is composed predominantly of atoms consisting of protons, neutrons and electrons that constitutes the observable universe and that is interconvertible with energy.” (Merriam-Webster Online Dictionary)

Over the years, the theory of matter has evolved. In ancient times it was believed that matter is made up of four elements – earth, air, fire and water. This theory was rejected and it was instead proposed that matter is a single substance. The modern theory of matter states that matter is made of up of atoms. Atom is considered to be the basic unit of any element and can combine chemically to form molecules. Every atom consists of a nucleus which is positively charged. The nucleus itself contains two main particles: neutrons with no electrical charge and protons with positive electrical charge. Around the nucleus, there are negatively charged electrons. (Infoplease Encyclopedia Online)

The modern theory of matter can be attributed to the work of John Dalton. Dalton’s theory was based on four main concepts: (Capri, Anthony)

“All matter is composed of indivisible particles called atoms.
All atoms of a given element are identical. However, all atoms of different elements have different properties.
Chemical reactions involve the combination of atoms, not the destruction of atoms.
When elements react to form compounds, they react in defined, whole-number ratios.”
Although modern economic theory has been modified even more today, the essence of Dalton’s theory still remains valid. However, scientists have now discovered that atoms can be destroyed by nuclear reactions but not by chemical reactions.  Scientists also know that different kinds of atoms within an element are called “isotopes”.  Isotopes of an element may have the same chemical properties.

STATES OF MATTER

There are primarily three states of matter:

Gas
Liquid
Solid
The core properties of gases, liquids and gas are summarized as follows:  (Purdue: Educational Help)

Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior
Gas
Liquid
solid
assumes the shape and volume of its container
particles can move past one another
assumes the shape of the part of the container which it occupies
particles can move/slide past one another
retains a fixed volume and shape
rigid – particles locked into place
compressible
lots of free space between particles
not easily compressible
little free space between particles
not easily compressible
little free space between particles
flows easily
particles can move past one another
flows easily
particles can move/slide past one another
does not flow easily
rigid – particles cannot move/slide past one another
Analyzing solids, liquids and gases macroscopically and microscopically reveals many interesting elements. Solids are rigid in shape and have the ability to retain or hold their shape. Microscopically, the molecules of a solid stay put relative to each other. Crystalline solids are those whose molecules are arranged in an orderly fashion while amorphous solids are those whose molecules are not arranged in any orderly fashion. Liquids can be differentiated from solids in terms of their inability to hold any shape. Liquids can flow and can be poured. However, liquids keep the same volume. Microscopically, the molecules of a liquid are always moving around relative to each other. That is the primary reason why liquids can’t hold their shape. Gases can neither keep their shape nor their volume. Microscopically, the molecules of a gas don’t interact much and are not held together strongly. That is why gases can spread out and fill up as much space as they can.

CLASSIFICATION OF MATTER

Matter can be classified as follows:

Mixtures which can be further broken down into two main categories:

Heterogeneous Mixture which consists of two or more substances that are easily distinguishable for example soil, milk or granite.
Homogenous mixture can also be called solutions or two substances that are mixed in equal proportions throughout
Pure Substances which can be further broken down into two categories:

Elements are substances that are composed of one type of atom for example gold, carbon, silver etc. Elements are fundamental substances that cannot be broken down further by chemical means. A few elements can be seen in pure form such as mercury while others can be seen in chemical combination with others such as oxygen and hydrogen in water. To date, scientists have identified 116 different elements. (Carpi, Anthony)
Compounds are substances that contain atoms that are bonded to each other. A chemical change is required to separate these atoms. Examples of compounds are salt, water or oxygen. A single particle of a compound is called a molecule. Compounds have specific formulas for example water is always made up of two parts hydrogen and one part oxygen. This concept was first initiated by Joseph Proust, a French Chemist. He observed that “no matter how he caused different elements to reach with oxygen, they always reacted in defined proportions.” (Carpi, Anthony)
A quick overview of the classification of matter can be obtained from the following table: (Science Help Online Chemistry)

Matter

Substance

Mixture

Element
Substance made up of only one type of atom
Compound
Two or more elements that are chemically combined
Heterogeneous Mixture
Mixtures that are made up of more than one phase
Homogeneous Mixtures
Also called solutions.  Mixtures that are made up of only one phase
Examples – gold, silver, carbon, oxygen and hydrogen
Examples – water, carbon dioxide, sodium bicarbonate, carbon monoxide
Examples – sand, soil, chicken soup, pizza, chocolate chip cookies.
Examples – salt water, pure air, metal alloys, seltzer water
PROPERTIES OF MATTER

Properties of matter can be defined in terms of its relationship with mass and space. Overall, all matter has inertia and weight. All matter occupies space thus it has volume and impenetrability. Other properties may differ from one form of matter to another. These properties may include ductility, elasticity, hardness, malleability, tenacity, porosity etc. There are two basic types of properties that can be associated with matter:

Physical Properties are those that cannot change the chemical nature of matter. These may include color, smell, freezing point, boiling point, melting point, attraction, repulsion, opacity, viscosity and density.
Chemical Properties are those that can change the chemical nature of matter. These may include heat of combustion, electromotive force, reactivity with water etc.
All form of matter has physical and chemical properties. For example, if we take sodium, a break up of its physical and chemical properties would be as follows: (General Chemistry Virtual Textbook)

physical properties (25°C)
chemical properties
appearance: a soft, shiny metal

density: 0.97 g cm3

melting point: 97.5°C

boiling point: 960°C
forms an oxide Na2O and a hydride NaH

burns in air to form sodium peroxide Na2O2

reacts violently with water to release hydrogen gas

dissolves in liquid ammonia to form a deep blue solution
 

 

Properties of matter that can be observed in bulk matter are called macroscopic properties.  At the microscopic level, matter is usually characterized by its structure. Broadly speaking, properties of matter fall into two classes: extensive and intensive properties. Properties such as mass and volume depend on the quantity of matter and can be classified as extensive properties. A general rule is that the ratio of two extensive properties is always an intensive property.  An example of an intensive property of matter is density. All matter possesses a unique set of intensive properties that distinguish it from every other kind of matter. In essence, intensive properties actually characterize matter. (General Chemistry Virtual Textbook)

 

CONCLUSION

The theory of matter has evolved over the past decade. From the ancient point of view that matter is made of earth, air, fire and water to the current point of view that matter is composed predominantly of atoms consisting of protons, neutrons and electrons, scientists have come a long way in identifying matter, its structure, its states, properties and classification.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Works Cited

Capri, Anthony. Atoms from Democritus to Dalton. December 21, 2006.

http://www.visionlearning.com/library/module_viewer.php?mid=49

 

The States of Matter. The Chemical Heritage Foundation. Online Tutorial. 2001. December 21, 2006

http://www.chemheritage.org/educationalservices/faces/poly/tutorial/states.htm

Early and Modern Theory of Matter. Infoplease Encyclopedia. December 21, 2006

http://www.infoplease.com/ce6/sci/A0832242.html

Classification and Properties of Matter. General Chemistry Virtual Textbook. December

21, 2006 http://www.chem1.com/acad/webtext/pre/matter.html

Definition of Matter. Merriam-Webster Online Dictionary. December 21, 2006

 

http://www.m-w.com/dictionary/matter

 

States of Matter. Purdue Educational Help.  December 21, 2006

 

http://www.chem.purdue.edu/gchelp/atoms/states.html

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