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Chemistry, the science of the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.
chemistry, Science that deals with the properties, composition, and structure of substances (elements and compounds), the reactions and transformations they undergo, and the energy released or absorbed during those processes.
The Greek concept of an element, which was accepted for nearly 2,000 years, contained only one aspect of the modern definition—namely, that elements have characteristic properties.
Structural chemistry is concerned with valence, which determines how atoms combine in definite ratios and how this is related to the bond directions and bond lengths. The properties of molecules correlate with their structures; for example, the water molecule is bent structurally and therefore has a dipole moment, whereas the carbon dioxide ...
Today experimental chemistry provides innumerable examples, and theoretical chemistry allows an understanding of their meaning. Basic concepts of chemical reactions Synthesis. When making a new substance from other substances, chemists say either that they carry out a synthesis or that they synthesize the new material.
solution, in chemistry, a homogenous mixture of two or more substances in relative amounts that can be varied continuously up to what is called the limit of solubility. The term solution is commonly applied to the liquid state of matter, but solutions of gases and solids are possible.
The fundamental principle of the science of chemistry is that the atoms of different elements can combine with one another to form chemical compounds. Methane , for example, which is formed from the elements carbon and hydrogen in the ratio four hydrogen atoms for each carbon atom, is known to contain distinct CH 4 molecules.
mole, in chemistry, a standard scientific unit for measuring large quantities of very small entities such as atoms, molecules, or other specified particles. The mole designates an extremely large number of units, 6.02214076 × 10 23 .
Periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number. When the elements are thus arranged, there is a recurring pattern called the ‘periodic law’ in their properties, in which elements in the same column (group) have similar properties.
Chemistry is a complex subject with many fields of study. For example, organic chemists deal only with compounds of the element carbon. Physical chemists measure the way that substances change during chemical reactions. Biochemists study chemical processes that happen in living things.