- published: 09 Dec 2015
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2015 (MMXV) will be a common year starting on Thursday. In the Gregorian calendar, it is the 2015th year in the Common Era (or Anno Domini), the 15th year of the 3rd millennium and 21st century, and the 6th of the 2010s decade.
Chemistry is the science of atomic matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.
Chemistry is sometimes called "the central science" because it connects physics with other natural sciences such as geology and biology. Chemistry is a branch of physical science but distinct from physics.
The etymology of the word chemistry has been much disputed. The genesis of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the Middle East.
Traditional chemistry starts with the study of elementary particles, atoms, molecules,substances, metals, crystals and other aggregates of matter. in solid, liquid, and gas states, whether in isolation or combination. The interactions, reactions and transformations that are studied in chemistry are usually a result of interaction between atoms, leading to rearrangments in the chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory.
Presentation is the practice of showing and explaining the content of a topic to an audience or learner. Presentations come in nearly as many forms as there are life situations. In the business world, there are sales presentations, informational and motivational presentations, first encounters, interviews, briefings, status reports, image-building, and of course, the inevitable training sessions.
Although individuals most often think of presentations in a business meeting context, there are countless occasions when that is not the case. For example, a Non Profit Organization presents the need for a capital fund-raising campaign to benefit the victims of a recent tragedy; a school district superintendent presents a program to parents about the introduction of foreign-language instruction in the elementary schools;an artist demonstrates decorative painting techniques to a group of interior designers; a horticulturist shows garden club members or homeowners how they might use native plants in the suburban landscape; a police officer addresses a neighborhood association about initiating a safety program.