CBSE NCERT Chemistry Class 11 Science – Nature of Matter NCERT Chemistry Class 11 : Takshila Learning is one of the largest growing unit providing online coaching classes for KG to class 12th offering animated videos, recorded lectures by experienced faculty, and notes on various subjects related to school syllabus and various professional courses. Our aim is to provide quality and result oriented education with holistic guidance to students. In the following article, we will discuss “the nature of matter and laws of chemical combination” from Unit I of chemistry Class 11 science– some basic concepts. Chemistry notes for class 11 : Matter- Any physical substance which occupies space and possesses mass is called matter. Atoms and molecules are all composed of matter. There are three fundamental states (sometimes called phases) of matter; Solids, Liquids and Gases. It is the physical state of the molecules and atoms that makes the different states of matter. The two other states of matter are Plasmas and Bose-Einstein condensate (BEC). In nature, matter is found in three different forms, based on their composition. These forms are
Elements: An element is the simplest type of matter. It has unique physical and chemical properties. An element is made up of only one kind of an atom. However, an atom is the smallest constituent unit of matter. Various elements occur in nature like oxygen (O), aluminium (Al), copper (Cu), silicon (Si), etc.The physical properties of a piece of silicon, such as colour, density, etc. is different from that of a piece of aluminium. This is because the properties of their atoms are different. Hence, each element is unique as the properties of its atoms are unique. Compounds: A compound is a matter that consists of two or more different elements that are bonded chemically.While, a molecule is formed when two or more atoms or elements (may be same type or different types) join together chemically. So, acompound is a molecule that contains at least two different elements. For example O2 is a molecule (diatomic) as it contains 2 oxygen atoms that are chemically bonded, but CO2 is a compound containing two different atoms, Carbon and Oxygen that are bondedchemically. Mixtures:A mixture is said to be a matter which consists of two or more elements or compounds that are only physically intermixed. For example, NaCl (common salt) is added to H2O (water), mixture of compounds NaCl and water is prepared. The elements and the compounds are considered as substances. A substance is a matter whose composition is fixed. Mixtures are not considered as substances because their composition varies, but they maintain many properties of its constituent elements or compounds. In the above example of mixture of salt and water, the components NaCl and water can vary in terms of their mass. But, this mixture is colourless like water and salty like sodium chloride.