The meaning of elements is any of the fundamental substances that consist of atoms of only one kind and that singly or in combination constitute all matter. Definition of Compound A compound is a substance formed when two or more chemical elements are chemically bonded together. Two types of chemical bonds common in compounds are covalent bonds and ionic bonds. The elements in any compound are always present in fixed ratios. Example 1: Pure water is a compound made from two elements - hydrogen and oxygen. The ratio of hydrogen to oxygen in water is always 2:1. Each molecule of water contains two hydrogen atoms bonded to a single oxygen atom. Example 2: Pure table salt is a compound made from two elements - sodium and chlorine. The ratio of sodium ions to chloride ions in sodium chloride is always 1:1. Example 3: Pure methane is a compound made from two elements - carbon and hydrogen. The ration of hydrogen to carbon in methane is always 4:1. Compounds can be decomposed chemically into their constituent elements. Suspension in science refers to a mixture of small particles dispersed in a liquid. The particles contained in a suspension are larger than those found in solutions. You can disturb the contents of such a suspension by shaking the container to allow the components to settle at the bottom. A colloid is a substance microscopically dispersed throughout another substance.[1] The dispersed-phase particles have a diameter of between approximately 1 and 1000 nanometers.[2] Such particles are normally invisible in an optical microscope, though their presence can be confirmed with the use of an ultramicroscope or an electron microscope. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions, or hydrosols. The dispersed-phase particles or droplets are affected largely by the surface chemistry present in the colloid. Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color. Colloidal solutions (also called colloidal suspensions) are the subject of interface and colloid science. This field of study was introduced in 1861 by Scottish scientist Thomas Graham. Organic refers to the way agricultural products, including foods and fibres such as cotton, are grown and processed. The word "organic" on the label stands for a commitment to an agriculture which strives for a balance with nature, using methods and materials which are of low impact to the environment. Organic production systems: Replenish and maintain soil fertility. Eliminate the use of toxic and persistent chemical pesticides and fertilizers. Build a biologically diverse agriculture. Organic foods are minimally processed to maintain the integrity of the foods without artificial ingredients, preservatives or irradiation. The following definition of "organic" was passed by the National Organic Standards Board in April, 1995: "Organic agriculture is an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony." Inorganic chemistry is the study of the synthesis and behavior of inorganic and organometallic compounds. This field covers all chemical compounds except the myriad organic compounds (carbon based compounds, usually containing C-H bonds), which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, and there is much overlap, most importantly in the sub-discipline of organometallic chemistry. It has applications in every aspect of the chemical industry–including catalysis, materials science, pigments, surfactants, coatings, medicine, fuel, and agriculture. [1]
Posted on: Mon, 01 Jul 2013 11:26:39 +0000
Trending Topics
Recently Viewed Topics
© 2015