Elements are the building blocks of matter. An element is a substance that contains only one type of atom and which cannot be broken down chemically
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- Bu sahifa navigatsiya:
- 1. What am I Choose from: compound, element, formula, reaction, salt, solution, symbol, water.
- 2. Complete the sentences using the appropriate passive forms of these verbs: break down, form, hold, make up, take.
- ACTIVE VOCABULARY English Uzbek Russian
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Elements are the building blocks of matter. An element is a substance that contains only one type of atom and which cannot be broken down chemically. When different elements have a reaction, atoms form chemical bonds with other atoms and create compounds. Therefore, a compound is a substance that is made up of two or more different elements which are chemically bonded together. The formation of a compound involves a chemical reaction. In compounds, bonds are formed and broken down by chemical forces. Compounds cannot be broken down by physical forces. The properties of a compound are often totally different from the properties of the original elements. For example, sodium alone is very reactive, but when it combines with chlorine (another reactive element) they form a non-reactive substance called sodium chloride (salt: NaCl). The compound has none of the traits of the original elements. Ionic and covalent bonds hold the atoms of the elements together. In ionic bonding, atoms lose or gain electrons to form charged particles (ions) which are strongly attracted to one another. In covalent bonding, atoms share electrons with other atoms. Scientists have found it very useful to give symbols to the different elements. 10 The symbol consists of one or two letters taken from the Latin or English name for the element. The formula for a compound is made using the symbols of the elements in the compound. It tells you which elements the compound is made from and how much of each element there is in it. Mixtures are usually how you find things in nature. A mixture is a system of two or more distinct chemical substances. The components in a mixture retain their individual chemical properties. Unlike compounds, mixtures can be separated by physical means (distillation, crystallization, etc.). Heterogeneous mixtures have distinguishable phases. Homogeneous mixtures are those in which the atoms or molecules are interspersed, as in a mixture of gases. Solutions are homogeneous mixtures. They can be solids, liquids, or gases dissolved in liquids, or also gases dissolved in other gases. The solute is the substance being dissolved; the solvent is the one doing the dissolving. Water is a very common solvent. QUESTIONS: 1. What are the building blocks of matter? 2. What is the formation of a compound involves? 3. What is mixture? EXERCISES: 1. What am I? Choose from: compound, element, formula, reaction, salt, solution, symbol, water. a. I’m a substance that consists of only one type of atom. I’m an ... b. I’m one or two letters representing a chemical substance. I’m a ... 11 c. I’m a substance consisting of two or more elements chemically combined. I’m a ... d. I’m a set of letters and numbers showing the elements that a substance is made of. I’m a ... e. I’m the chemical change caused in a substance when it combines with another. I’m a ... f. I’m a mixture of a solute and a solvent that does not separate out. I’m a ... g. I’m the solute in salt water. I’m ... h. I’m the solvent in salt water. I’m ... 2. Complete the sentences using the appropriate passive forms of these verbs: break down, form, hold, make up, take. a. Matter ... of elements. b. Compounds ... by elements. c. Symbols ... from Latin or English words. d. The atoms of the elements ...together by covalent and ionic bonds. e. Chemical bonds are formed and ... by chemical forces.
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