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Element, Compound And Mixture

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Published in: Physics
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as we know element, compound and mixtures are the three basic constituents of modern chemistry, hereby i am uploading a presentation which will briefly describe these things along with their property

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  1. swn?x?w SONIFlOdW03 'SIN3W373
  2. Classification of Matter Matter is a substance that occupy space and has mass. Matter can be classified into i. Pure Matter ' ii. Impure Matter (a) Atoms of an element of a compound (b) Molecules of an element (d) N/lixture of elennenfs and a compound
  3. Pure Substances and Mixtures If matter is not uniform throughout, then it is a heterogeneous mixture. If matter is uniform throughout, it is homogeneous. If homogeneous matter can be separated by physical means, then the matter is a mixture. If homogeneous matter cannot be separated by physical means, then the matter is a pure substance. If a pure substance can be decomposed into something else, then the substance is a compound. If a pure substance cannot be decomposed into something else, then the substance is an element. 3
  4. NO Heterogeneous mixture NO Element Matter Is it uniform throughout? NO Can it be separated into simpler substances? YES Homogeneous Does it have a variable composition? YES Compound YES
  5. CHARACTERISTICS OF PURE & IMPURE SUBSTANCES — A pure substance boils at a constant temperature i.e. it has a fix boiling point. An impure liquid could boil higher than the expected boiling point and over a range of temperature. — A pure substance melts quite sharply at the melting point. An impure solid melts below its expected melting point and more slowly over a wider temperature range.
  6. Elements Element consist of unique type of atoms. Element cannot be further broken into simple substance by any chemical or physical means. There are 118 elements known. Each element is given a unique chemical symbol (one or two letters). Elements are building blocks of matter.
  7. 000 o 0 000 o O o a Elements A sample of lead atoms (Pb). All atoms in the sample consist of lead, so the substance is homogeneous. A sample of chlorine atoms (CI). All atoms in the sample consist of chlorine, so the substance is homogeneous. 7
  8. Elements The earth's crust consists of 5 main elements. The human body consists mostly of 3 main elements. Aluminum Iron 4.7% Calcium 3.40/0 7.5% Other 9.2% Silicon 25.7% Oxygen 49.5% Oxygen 650/0 Other Hydrogen Carbon 18% Earth's crust (a) Human body (b)
  9. Classification of Elements as Metals & Non- Metals S.No 1 2 3 4 5 METALS Good conductors of electricity & heat Shiny in appearance Strong & hard Malleable & ductile Sonorous NON- METALS Bad conductors of heat & electricity Usually dull in appearance Usually weak & soft Brittle Non- Sonorous
  10. ELEMENTS & SYMBOLS IjVJdiffiYLS NAME SYMBOL PHYSICA S.N0 dib 1 2 3 4 5 6 7 8 9 10 Aluminium Calcium Copper Iron Magnesium Mercury Potassium Sodium Zinc Gold Al Ca cu Mg K Zn L STATE Solid Solid Solid Solid Solid Liquid Solid Solid Solid Solid NAME Argon Bromine Carbon Chlorine Silicon Sulphur Hydrogen Iodine Nitrogen oxygen SYMBOL c Cl Si S 1 O PHYSICAL STATE Gas Liquid Solid Gas Solid Solid Gas Solid Gas Gas * Physical states are given at room temperature.
  11. Compounds Most elements react to form compounds. , Example, The proportions of elements in compounds are the same irrespective of how the compound was formed. The composition of a pure compound is always the same. If water is decomposed, then there will always be twice as much hydrogen gas formed as oxygen gas.
  12. CHARACTERISTICS OF COMPOUND ' It is a pure substance. ' It is always homogenous ' Represented by a FORMULA, eg sodium chloride NaCI, methane CH4 and glucose C6H1206 There must be at least two different types of atom (elements) in a compound. Have a fixed composition and therefore a fixed ratio of atoms represented by a fixed formula. 12
  13. CHARACTERISTICS OF COMPOUND Elements are not easily separated by physical means. The compound has properties quite different from the elements it is formed from. The formula of a compound summarizes the 'whole number' atomic ratio of what it is made up of eg methane CH4 is composed of 1 carbon atom combined with 4 hydrogen atoms. The word formula can also apply to elements. eg hydrogen 1-12, oxygen 02, ozone 03, phosphorus P 4 13
  14. Compounds ' Lead has two charges listed, +2 and +4. This is a sample of lead (Il) chloride (PbC12). Two or more elements bonded in a whole- number ratio is a COMPOUND. This compound is formed from the +4 version of lead. This is lead (IV) chloride (PbC14). Notice how both samples of lead compounds have consistent composition throughout? Compounds are homogeneous! 14
  15. Types of Compounds . made of metal and nonmetal ions. Form an ionic Ionic crystal lattice when in the solid phase. Ions separate when melted or dissolved in water, allowing electrical conduction. Examples: NaCI, 1
  16. Ionic Compounds Ionic Crystal Structure, then adding heat (or dissolving in water) to break up the crystal into a liquid composed of free-moving ions. Melting or Dissolving in Water Ionic crystal: alternating + and - ions held in place by electrostatic attraction Electrostatic attraction overcome. ions free to move about on their own- Allows for electrical current to be conducted-
  17. Molecular Compounds Covalent (molecular) crystal lattice, melting to form freely-moving molecules Addition of heat Covalent Crystal Lattice: molecules of water are attracted to each other with InterMolecuIar Attractive Forces- These hold the molecules together in a regular geometric pattern- Since 'MAF are weaker than ionic attractions these crystal lattices tend to be weak. and therefore *Oft and easy to melt- When melted. the molecules separate from each other- The covalent bonds do not break. iust the IMAF- The molecular liquid does not have charged particles like ionic liquids do. therefore molecular liquids cannot conduct electricity-
  18. Network Solids Network solids are made of nonmetal atoms covalently bonded together to form large crystal lattices. No individual molecules can be distinguished. Examples include Si02 (quartz). Corundum (A1203) also forms these, even though Al is considered a metal. Network solids are among the hardest materials known. They have extremely high melting points and do not conduct electricity. 18
  19. EXAMPLES OF SOME FORMULA S.No. 1 2 3 COMPOUND Water Sodium hydroxide Calcium carbonate Ethanol Sulphuric acid Barium nitrate FORMULA H 20 NaOH CaC03 C2H50H Ba NO ELEMENT Hydrogen Oxygen Chlorine Nitrogen Fluorine Bromine FORMULA 02
  20. Mixtures Heterogeneous mixtures are not uniform throughout. Homogeneous mixtures are uniform throughout. Homogeneous mixtures are called solutions. 20
  21. 00 0 0000 o Mixtures A mixture of lead atoms and chlorine atoms. They exist in no particular ratio and are not chemically combined with each other. They can be separated by physical means. A mixture of PbC12 and PbC14 formula units. Again, they are in no particular ratio to each other and can be separated without chemical change. 21
  22. CHARACTERISTICS OF MIXTURE ' It is an impure substance ' No formula They can be mixed in any ratio. The properties of the mixture are the properties of its constituents. ' Constituents can be easily seperated by physical methods e.g. heating, drying, crystallization, distillation etc. ' It is either homogenous or heterogenous. 22
  23. DIFFERENCE BETWEEN COMPOUNDS & MIXTURES 1 2 4 The substance are mixed together, no reaction take place. Composition can be varied Properties of the constituents present, remain same. Can be separated by physical method such as filtration distillation etc. Substance chemically react to form a new compound. Composition of new compound is always same. The properties of new compound are very different from those of the element in it. Cannot easily be separated into its elements. 23
  24. 8 8 8 GAS 8 ? 0 8 8 LIQUID 8 0 8 8 0 8 8 8 0 8 0 8 8 8 8 88 0 88 0 SOLID 8 8 diatomic heliUrn and 8 -. ,. ~ - ? carnpaunds-. 0. compound* bath - ? elzrnznt - d m - ? :c “ : - heliur-n both m - ? “ c : … , m ? x : r : ? Kr N ? ? ? single 0. - ? r ? ? S both mo :c “ : - d zlernznt. ? rr• n - ? - ? d ? ? m ? · " “ chloride C07 ~ 174EZ | ? S - ? … ? , ? · ? ? n and helium ? e hydrogen H ? ? ? ? ? hydrogen chloride krypton and neat—I ? ? F ? - chloride hydrogen ? e ? ? ? eg N2 N ? ?
  25. Physical vs. Chemical Properties Physical properties can be measure without changing the basic identity of the substance (e.g., color, density, odor, melting point) Chemical properties describe how substances react or change to form different substances (e.g., hydrogen burns in oxygen) Intensive physical properties do not depend on how much of the substance is present. - Examples: density, temperature, and melting point. Extensive physical properties depend on the amount of substance present. - Examples: mass, volume, pressure. 25
  26. Physical and Chemical Changes When a substance undergoes a physical change, its physical appearance changes. - Ice melts: a solid is converted into a liquid. Physical changes do not result in a change of composition. When a substance changes its composition, it undergoes a chemical change: - When pure hydrogen and pure oxygen react completely, they form pure water. In the flask containing water, there is no oxygen or hydrogen left over. 26
  27. TESTING THE PURITY OF A SUBSTANCE S.No 1 2 3 TEST MELTING POINT BOILING POINT CHROMATOGRAPHY It melts at a fix temperature e.g pure naphthalene melts at 800c It boils at fixed temperature e.g. pure ethanol boils at 780C Pure substance will form one spot IMPURE SUBSTANCE Do not have a fix melting point. It melts at a range of temperature. Impurity lower down the m.p. The greater the % of impurity the lower the m.p. e.g. impure naphthalene melts at 760C to 780c. It boils at a range of temperature e.g. petrol boils at 350c to 750c. Impure substance will form several spots.
  28. THE END 28

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