ELEMET, COMPOUND AND MIXTURE

                                   Element, Compound and  Mixture



Note that an element:

  1.  consists of only one kind of atom,
   2 .cannot be broken down into a simpler type of matter by either physical or chemical means, and
    3.can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen).

A molecule consists of two or more atoms of the same element, or different elements, that are chemically bound together. Note that the two nitrogen atoms which comprise a nitrogen molecule move as a unit.ElementsAn element is defined as a pure substance made up of one type of atoms and cannot be further subdivided into simpler substances by any physical or chemical means.An element can be represented by using a symbol.Examples of Elements:The symbols H2 and Fe represent the elements Hydrogen and Iron respectivelyElement- is a pure substance (homogeneous material) that broken down further (decomposed) by ordinary chemical means. (An element is made of only one kind of atom). Example: aluminum, hydrogen, calcium, mercury.Elements are listed on the periodic table. Scientists have found 90 elements in nature, and about 20 more have been produced in the laboratory.


Note that a compound:

    1.consists of atoms of two or more different elements bound together,
   2. can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means),
    3.has properties that are different from its component elements, and
    4.always contains the same ratio of its component atoms.
Compound- two or more elements chemically combined. (Note: if a sample of matter is made of atoms of two or more elements joined together, always in the same ratio, then that matter is a compound.)
Example: alcohol (C2H5OH), water (H2O), salt (NaCl), sugar C12H22O11) ammonia (NH3).Examples of CompoundsThe chemical formulae H2O and FeS represent the compounds water and Ferrous sulfide (Iron [I] sulfide) respectively.
NOTE: When scientists refer to substances, they mean elements or compounds. A substance always has a definite composition.Compounds
A compound is defined as a pure substance made up of two or more types of elements (atoms) chemically combined in a fixed proportion, and it can be further subdivided into simpler substances by chemical means only.A molecule is the smallest part of a compound, whose properties are the same as those of the compound.A compound can be represented by using a chemical formula.

Note that a mixture:

    1.consists of two or more different elements and/or compounds physically intermingled,
    2.can be separated into its components by physical means, and
   3. often retains many of the properties of its components.
Mixture- two or more elements or compounds that are blended without combining chemically. Each part of the matter in a mixture has its own identity (properties). Mixtures can be separated using physical or mechanical means.
Example: fabrics, vinegar, soil, rocks, rocks, milk, lemonade
Mixtures can be heterogeneous mixtures or homogeneous mixtures.A mixture is defined as an impure substance made up of two or more types of elements (atoms) or compounds or both mechanically mixed in any proportion, and it can be further subdivided into simpler substances by physical (mechanical) means.The constituents of a mixture retain their original properties.The constituents of a homogenous mixture are uniformly mixed thoroughout the mixture. The properties and composition of a homogenous mixture are the same throughout the mixture.The constituents of a heterogenous mixture are not uniformly mixed thoroughout the mixture. The properties and composition of a heterogenous mixture are not the same throughout the mixture.

Examples of Mixtures:Stainless steel is a mixture (alloy) of iron, carbon, chromium, and nickel. Carbon gives hardness to the mixture. Chromium and nickel give a silvery look to the mixture.Potassium sulfide solution is a homogenous mixture.A mixture of water and oil is heterogenous in nature. 

    Heterogeneous mixtures- the substances in the kind of a mixture are not spread out  evenly. Example: a bottle of liquid salad dressing.

    Homogeneous mixtures- the substances are spread evenly throughout, a homogeneous mixture is called a solution. Example: vinegar (water and acetic acid are mixed evenly throughout). Other examples: sea water, soft drinks, glass


Solution- a homogeneous mixture in which one substance (the solute) is dissolved in another substance (the solvent). Example: salt water (Water, the solvent, plus salt, the solute, produces the solution of salty water.)

Suspension- a heterogeneous mixture in which the particles are large enough to be seen by a microscope or the unaided eye (eventually, they settle out of the mixture). Example: stirring a teaspoon of dirt in a glass of water.

Colloid- a mixture where the size of particles in the mixture are between those of a solution and a suspension. NOTE: The particles appear evenly distributed. Examples: fog, cheese, butter, jellies, whipped cream.