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ICT Project about Chemistry. Introduction to Chemistry. Atom: The smallest part of an element that can exist. Element: A substance which cannot be broken down into simpler substances, Ex. Copper(Cu) , Silver(Ag) . Molecule: The smallest part of a substance in the free state.
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Introduction to Chemistry • Atom:The smallest part of an element that can exist. • Element:A substance which cannot be broken down into simpler substances,Ex. Copper(Cu), Silver(Ag). • Molecule:The smallest part of a substance in the free state. • Mixture:This is made up of two or more elements or compounds mixed together. The components of the mixture can be easily separated. • Compound: A substance made up of two or more elements chemically combined together.
Mixtures: The constituents of a mixture can be separated from each other by physical means. Mixtures have different compositions. When making a mixture heat is not involved. The properties of a mixture are the sum of the properties of its constituents. Compounds The constituents of a compound cannot be easily separated. Compounds are absolutely fixed in their composition by weight. Heat is involved when compounds are formed. The properties of a compound are very different from the properties of its constituents. Mixtures and Compounds
States of matter There are three states of matter: solid, liquid, and gas/vapour. To change one state to another, heat is involved. An increase in temperature causes the particles to move faster and push each other farther apart, so that a solid changes into a liquid, and a liquid into a gas.
About ¾ of the Earth’s surface is covered with water (ocean). But only 1% of this water is fresh. Properties of pure water: Boils at 100ºC. Freezes at 0ºC. Water is odorless, colorless and neutral to litmus and also tasteless. Water with impurities in it will boil at a temperature HIGHER than 100ºC and it will freeze at a LOWER temperature than 0ºC. Water