Classification Of Matter

Classification Of Matter

Matter is anything that occupies the space and has a mass. For example, your textbook, trees, table, etc. Then what is the mass? The mass is the amount of matter in an object, which is not the same thing as its weight. The weight is a measure of the gravitational force exerted on an object. As long as the gravity is uniform (earth’s surface), the weight does not change. Hence, we can freely use the word mass or weight; it does not make any difference. However, if the gravitational forces are not the same (earth vs. moon), the weight differs from the mass. For example, the same astronaut (same mass) weighs differently on earth and on moon.

1) Atom

Atoms are the basic units of matter and the defining structure of elements. Atoms are made up of three particles: protons, neutrons and electrons. Protons and neutrons are heavier than electrons and reside in the center of the atom, which is called the nucleus. Electrons are extremely lightweight and exist in a cloud orbiting the nucleus. The electron cloud has a radius 10,000 times greater than the nucleus. Protons and neutrons have approximately the same mass. However, one proton weighs more than 1,800 electrons. Atoms always have an equal number of protons and electrons, and the number of protons and neutrons is usually the same as well. Adding a proton to an atom makes a new element, while adding a neutron makes an isotope, or heavier version, of that atom.

2) Element

An element is a substance consisting of atoms which all have the same number of protons or the same atomic number. Elements are chemically the simplest substances and hence cannot be broken down using chemical methods. Elements can only be changed into other elements using nuclear methods. Although an element's atoms must all have the same number of protons, they can have different numbers of neutrons and hence different masses. When atoms of the same element have different numbers of neutrons, they are called isotopes.

List of facts about Chemical Elements:

 -    Elements consist of only one type of atom. Which may, or may not be joined together for  

      molecules or large structures

-       Elements can exist either as atoms (e.g. : argon) or as molecules ( e.g. nitrogen)

-       Elements cannot be broken down into a simpler type of matter by either physical or chemical techniques, though some larger elements break-down spontaneously due to being radioactive

-        Elements are listed in the periodic table

3)  Compound

In chemistry, a compound is a substance that results from a combination of two or more different chemical element s, in such a way that the atom s of the different elements are held together by chemical bonds that are difficult to break. These bonds form as a result of the sharing or exchange of electron s among the atoms. The smallest unbreakable molecule . A compound differs from a mixture, in which bonding among the atoms of the constituent substances does not occur. In some situations, different elements react with each other when they are mixed, forming bonds among the atoms and thereby producing molecules of a compound. In other scenarios, different elements can be mixed and no reaction occurs, so the elements retain their individual identities. Sometimes, when elements are mixed, the reaction occurs slowly (as when iron is exposed to oxygen); in other cases it takes place rapidly (as when lithium is exposed to oxygen). Sometimes, when an element is exposed to a compound, a reaction occurs in which new compounds are formed (as when pure elemental sodium is immersed in liquid water). Often, a compound looks and behaves nothing like any of the elements that comprise it. Consider, for example, hydrogen (H) and oxygen (O). Both of these elements are gases at room temperature and normal atmospheric pressure. But when they combine into the familiar compound known as water, each molecule of which contains two hydrogen atoms and one oxygen atom (H ₂ O), the resulting substance is a liquid at room temperature and normal atmospheric pressure. The atoms of a few elements do not readily bond with other elements to form compounds. These are called noble or inert gases: helium, neon, argon, krypton, xenon, and radon. Certain elements readily combine with other elements to form compounds. Examples are oxygen, chlorine, and fluorine.

4) Mixture

In chemistry, a mixture forms when two or more substances are combined such that each substance retains its own chemical identity. Chemical bonds between the components are neither broken nor formed. Note that even though the chemical properties of the components haven't changed, a mixture may exhibit new physical properties, like boiling point and melting point.

EXAMPLES OF MIXTURES

• Flour and sugar may be combined to form a mixture.
• Sugar and water form a mixture.
• Marbles and salt may be combined to form a mixture.
• Smoke is a mixture of solid particles and gases.

TYPES OF MIXTURES

Two broad categories of mixtures are heterogeneous and homogeneous mixtures. Heterogeneous mixtures are not uniform throughout the composition (e.g. gravel), while homogeneous mixtures have the same phase and composition, no matter where you sample them (e.g., air). The distinction between heterogeneous and homogeneous mixtures is a matter of magnification or scale. For example, even air can appear to be heterogenous if your sample only contains a few molecules, while a bag of mixed vegetables may appear homogeneous if your sample is an entire truckload full of them. Also note, even if a sample consists of a single element, it may form a heterogeneous mixture. One example would be a mixture of pencil lead and diamonds (both carbon). Another example could be a mixture of gold powder and nuggets.

Besides being classified as heterogeneous or homogeneous, mixtures may also be described according to the particle size of the components:

Solution - A chemical solution contains very small particle sizes (less than 1 nanometer in diameter). A solution is physically stable and the components cannot be separated by decanting or centrifuging the sample. Examples of solutions include air (gas), dissolved oxygen in water (liquid), and mercury in gold amalgam (solid), opal (solid), and gelatin (solid).

Colloid - A colloidal solution appears homogeneous to the naked eye, but particles are apparent under microscope magnification. Particle sizes range from 1 nanometer to 1 micrometer. Like solutions, colloids are physically stable. They exhibit the Tyndall effect. Colloid components can't be separated using decantation, but may be isolated by centrifugation. Examples of colloids include hair spray (gas), smoke (gas), whipped cream (liquid foam), blood (liquid), 

Suspension - Particles in a suspension are often large enough that the mixture appears heterogeneous. Stabilizing agents are required to keep the particles from separating. Like colloids, suspensions exhibit the Tyndall effect. Suspensions may be separated using either decantation or centrifugation. Examples of suspensions include dust in air (solid in gas), vinaigrette (liquid in liquid), mud (solid in liquid), sand (solids blended together), and granite (blended solids).