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CHEMISTRY

CHEMISTRY. Chapter 2 Atoms, Molecules, and Ions. Daltons' Atomic Theory نظرية دالتون في الذرة. نظرية دالتون في الذرة: يعتبرالعالم دالتون أول من فرّق بين نوعين من المادة وحيدة التكوين substance . 1- عناصر Elements 2- مركبات Compounds ووضع الفرضيات التالية:

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CHEMISTRY

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  1. CHEMISTRY Chapter 2Atoms, Molecules, and Ions

  2. Daltons' Atomic Theoryنظرية دالتون في الذرة نظرية دالتون في الذرة: يعتبرالعالم دالتون أول من فرّق بين نوعين من المادة وحيدة التكوين substance. 1- عناصر Elements 2- مركباتCompounds ووضع الفرضيات التالية: 1- الذرة أصغر جزء من العنصر ولاتتجزأ بالوسائل الاعتيادية . 2- ذرات العنصر الواحد تتشابه في الخواص الفيزيائية والكيميائية . 3- الجزيء أصغر جزء من المركب , ويتكون من اتحاد ذرتين أو أكثر

  3. Daltons' Atomic Theoryنظرية دالتون في الذرة 4- جزيئات المركب الواحد متشابهة في الخواص الفيزيائية والكيميائية . 5- الذرة مصانة في التفاعل الكيميائي . 6- التفاعل الكيميائي , يحدث بين الذرات , وما هو في الحقيقة سوى إعادة لترتيب الذرات. .

  4. John Dalton and his Atomic Theory Introduction: Dalton was the first to distinguish between two types of substance: -Elements -Compounds 1-Atom is the smallest unit of the element and cannot be broken down by ordinary chemical operations. Daltons' Atomic Theoryنظرية دالتون في الذرة 4

  5. 2-All atoms of an element are alike in the physical and chemical properties. 3-Molecule is smallest unit of the compound and it is composed of 2 atoms or more. 4-All molecules of the same compound are alike in physical and chemical properties. 5-Aoms are conserved during the chemical reaction. 6- the chemical reaction takes place between the atoms, and the chemical reaction is a new rearrangement of the atoms to produce new compounds. Daltons' Atomic Theoryنظرية دالتون في الذرة 5

  6. INTERNATIONAL UNVERSITY FOR SCIENCE & TECHNOLOGY The Combination Laws in Chemistry قوانين الاتحادات الكيميائية

  7. قانون انحفاظ المادة The Conservation Law in Chemistry Lavoisier's Law -المادة مصانة في التفاعل الكيميائي , ومجموع كتل المواد يبقى ثابتا لايتغيّرقبل التفاعل وبعد التفاعل . -The mass is conserved during the chemical reaction, and the total masses remain unchanged. المادة لاتفنى ولاتخلق من عدم , وإنما هناك تحوّل من شكل إلى شكل آخر . - Mass is neither created nor destroyed - مجموع أوزان المواد الداخلة في التفاعل , يساوي مجموع أوزان المواد الناتجة عن التفاعل . -The sum of reactant masses is equal to the sum of product masses.

  8. -The mass is conserved during the chemical reaction, and the total masses remain unchanged. - Mass is neither created nor destroyed -The sum of reactant masses is equal to the sum of product masses. قانون انحفاظ المادة The Conservation Law in Chemistry Lavoisier's Law 8

  9. The Conservation Law in Chemistry Lavoisier's Law قانون مصونية المادة على ضوء نظرية دالتون After Dalton's theory : حيث أن التفاعل الكيميائي يحدث بين الذرات , فإن قانون المصونية يكتي بالشكل : إن مجموع أعداد الذرات الداخلة في التفاعل , يساوي مجموع أعداد الذرات الناتجة عن التفاعل . قانون مصونية المادة على ضوء نظرية النسبية لآينستاين : بعد أفكار تحول المادة إلى طاقة , فأن قانون المصونية و يكتب بالشكل : إن مجموع أوزان المواد الداخلة في التفاعل , يساوي مجموع أوزان المواد الناتجة عن التفاعل و مع الأخذ بعين الاعتبار , تحول المادة إلى طاقة في التفاعلات الناشرة للحرارة , وتحول الطاقة إلى مادة في التفاعلات الماصة للحرارة .

  10. After Dalton's theory Since the chemical reaction happens between the atoms, we can write Lavoisier's law as: The sum of reactant atoms is equal to the sum of product atoms. The Conservation Law in Chemistry Lavoisier's Law 10

  11. قانون النسب الثابتة أو قانون بروستProust's Law or Definite Proportions Law قانون النسب الثابتة definite proportions law : إذا اتحد عنصران معا لتشكيل مركب ما , فإن اتحادهما يتم وفق نسبة وزنية ثابتة . فالهيدروجين يتحد مع الأوكسجين لتشكيل الماء , وتكون النسبة 2grams/16grams هي نسبة وزنية ثابتة . H₂ + O → H₂O 2g 16g 2g/16g (definite ratio) قانون النسب الثابتة بشكل عام Proust 'Law in general : في أي مركب هناك نسبة وزنية ثابتة بين أوزان العناصر المشكلة لهذا المركب . فحمض الكبريت H₂SO₄, تكون نسبة أوزان الهيدروجين للكبريت للأوكسجين , مساوية 2g/32g/64g

  12. قانون النسب الثابتة أو قانون بروستProust's Law or Definite Proportions Law If tow elements combine to form a compound, their combination will occur according to a fixed mass ratio, hydrogen combines with oxygen to form water with a mass ratio 2grams/16grams H₂ + O → H₂O 2g 16g 2g/16g (definite ratio) Proust 'Law: In any compound, there is a fixed ratio of masses between the elements of this compound. in other wards: All samples of the same compound have the same composition and the same properties. . 12

  13. قانون النسب الثابتة أو قانون بروستProust's Law or Definite Proportions Law Example(1): If the carbon combines with oxygen to form the carbon dioxide compound, this happens always between 12 grams of carbon and 32 grams of oxygen and the ratio 12/32 is a fixed mass ratio. C + O₂ → CO₂ 12 32 12g/32g is a fixed ratio. Example(2): In H₂SO₄ compound 2g/32g/64g is a fixed mass ratio. .

  14. قانون النسب الثابتة أو قانون بروستProust's Law or Definite Proportions Law Example The mass ratio of oxygen to carbon in the compound carbon monoxide is 12/16. What mass of oxygen which is needed to react with 0.3 g of carbon, and what is mass of produced CO? Solution: C + O ----------------- CO 12 16 x 0.3 The mass of oxygen = 0.3x 16/12 = 0.4 g The mass of carbon monoxide= 0.3 + 0.4 = 0.7 g

  15. قانون النسب الثابتة أو قانون بروستProust's Law or Definite Proportions Law قانون النسب الثابتة على ضوء نظرية دالتون : حيث أن التفاعل الكيميائي يحدث بين الذرات , يمكن صياغة قانون بروست بالشكل التالي : في أي مركب هناك نسبة عددية ثابتة بين ذرات العناصر المشكلة لهذا المركب . ففي حمض الكبيرت و تكون نسبة ذرات الهيدروجين للكبريت للأوكسجين مساوية 2/1/4

  16. Law of Multiple Proportions (cont’d) • If two elements combine to form more than one compound , the masses of one element that combine with a fixed mass of the second element are in the ratio of small whole numbers. • C + O → CO • 16 • C + O₂ → CO₂ • 12 32 • the 16/32=1/2 is a simple ratio Ratio of oxygen-to-carbon in CO2 is exactly twice the ratio in CO.

  17. Law of Multiple Proportions (cont’d) • Four different oxides of nitrogen can be formed by combining 28 g of nitrogen with: • 16 g oxygen, forming Compound I • 48 g oxygen, forming Compound II • 64 g oxygen, forming Compound III • 80 g oxygen, forming Compound IV What is the ratio 16:48:64:80 expressed as small whole numbers? • Compounds I–IV are N2O, N2O3, N2O4, N2O5 1:3:4:5

  18. The Discovery of Atomic Structure • Atoms are the building blocks of matter. • The ancient Greeks were the first to postulate that matter consists of indivisible constituents. • Later scientists realized that the atom consisted of charged entities.

  19. The Atom

  20. Class Practice Problem • The diameter of a U.S. penny is 19mm. The diameter of a copper atom, by comparison, is only 2.6 angstroms (Å). How many copper atoms could be arranged side by side in a straight line across the diameter of a penny?

  21. Keys and Terms in Chemistry 1-atom: It s the smallest distinctive unit of element and cannot be broken down by ordinary chemical operations. 2-: molecule It is the smallest distinctive unit of compound and it is composed of 2 atoms or more. 3-Ion: It is an atom or a group of atoms having positive or negative charges.

  22. Keys and Terms in Chemistry Q-Determine which of the following represent elements and which do not. C, CO, Cl, CaCl2 , Na, KI Q-Determine which of the following represent molecules and which do not. N , N₂ , No , NO , O , O₂ , O₃ , Os

  23. Keys and Terms in Chemistry 4-Atomic Mass: It is the mass of the atom given by the atomic mass unit (u). 5-Atomic Mass Unit ( a.m.u.): It is 1/12 of the mass of the ¹²₆C atom 6-Molculer Mass: It is the mass of molecule by the a.m.u. and equals the sum of all the masses of atoms in the formula.

  24. Keys and Terms in Chemistry 7- Gram Atomic Mass: It is the mass of atom in grams, and it is called the mole. 8- Gram Molecular Mass: It is the mass of molecule in grams, and it is called the mole. 9-Mole(Molar Mass): It is the mass of atom or molecule using gram as unit and it contains Avogadro's number of atoms or molecules.

  25. Keys and Terms in Chemistry 10-Avogadro's number: It is the number of atoms or molecules in the mole of atoms or molecules, and equals 6.023x10²³. 11-Avogadro's mole volume: At the standard conditions of pressure and temperature, the mole of any gas occupies a volume of 22.4 lit.

  26. Keys and Terms in Chemistry Q-Calculate the molecular mass of each of the following: Li2O, C3H7Br, (CH3CH2CH2)2O, KHSO3, N2O5, KNO2 Q-Calculate the number of moles of CO present in a 125 g sample of the gas. Q-Calculate the number of sodium atoms Na in 4.6 g of sodium metal? Q-Calculate the number of ammonium ions in 0.26 g of ammonium sulphate (NH₄)₂SO₄

  27. Keys and Terms in Chemistry 12-Atomic Number(Z): -It is the number of protons or number of electrons in neutral atom. -It is the identity card of the element. -It is the number of box of the element in the periodic table. 13-Mass Number(A): It is the sum of protons and neutrons in the nucleus.

  28. Elements and Symbols -Usually for the simplicity, we represent the elements by symbols, using the initial letter of the name in capital form, starting by the old known elements, so Carbon is represented by the letter C, but Calcium is represented by the symbol Ca and Cobalt by the symbol Co, ……, Nitrogen is represented by the symbol N and Nickel by the symbol Ni, etc…. In general we represent the elements by one capital letter or by two letters, the first is in capital form, while the second letter suppose to be in small form.

  29. Keys and Terms in Chemistry Isotopes 14-The Isotopes: Are atoms of the same element with the same atomic number and different mass number. -Each element has isotopes, some are stable and some are radioactive, for example carbon has three isotopes:¹³₆C, ¹⁴₆C¹²₆C, The isotope ¹⁴₆C , is radioactive.

  30. Atomic Mass (cont’d) Isotopes Question: do all isotopes of an element have the same mass? Why or why not? The atomic mass given on the periodic table is the weighted average of the masses of the naturally occurring isotopes of that element.

  31. Example : Use the data cited above to determine the weighted average atomic mass of carbon. A- To find the weighted average , we have to multiply the fractional abundance of each isotope with it’s atomic mass : Carbon-12=12x0.98892=11.86704 Carbon-13=13x0.01108=0.1534 The weighted average=12.02044

  32. Example: Which of the following pairs of symbols represent isotopes? Example: Indicate the numbers of protons, neutrons and electrons in the following atoms:

  33. Keys and Terms in Chemistry 15-Standard conditions of pressure and temperature: P=1 atm.= (76 cm/Hg) =(760 mm/Hg) T=273° deg. ( K°) At the sea level

  34. Atomic Weights • Average Atomic Masses • Relative atomic mass: average masses of isotopes: • Naturally occurring C: 98.892 % 12C + 1.108 % 13C. • Average mass of C: • (0.98892)(12 amu) + (0.0108)(13.00335) = 12.011 amu. • Atomic weight (AW) is also known as average atomic mass (atomic weight). • Atomic weights are listed on the periodic table.

  35. Electrons Electrons: J. Thompson used vacuum tube ( crocks tube ) with two electrodes , he applied a high voltage current between the electrodes about 3000 v and a low pressure of inert gas about 10ˉ⁵ Torr,he noticed that a beam of gluing rays comes from the cathode to the anode , he called it the cathodic rays. Thompson found that the cathodic rays are composed of tiny small particles with a mass and negative charge, called later electrons.

  36. Radiations Hennery Becquerel discovered the radiation activity in elements and found three types of rays : Alfa Rays (α): A beam of particles with a mass and positive charge ( He⁺⁺ nuclei ) with high energy and small penetration power. Beta Rays (β): A beam of particles with a mass and negative charge ( high speed electrons) with high energy and high penetrating power. Gamma Rays (γ): A beam of electromagnetic waves ( light) with very high energy and very high penetrating power.

  37. Protons and neutrons are located at the center of an atom (at the nucleus). Electrons are dispersed around the nucleus. Subatomic Particles 37

  38. -Mendeleev arranged the known elements in order of increasing atomic weightfrom left to right and from top to bottom in groups. -Elements that closely resembled one another were arranged in the same vertical group. -He found the chemical and physical properties are weight dependent . -Gaps were left where undiscovered elements should appear. -From the locations of the gaps, he was able to predict propertiesof some of the undiscovered elements. Mendeleev’s Periodic Table 38

  39. The Modern Periodic Table 39 Except for H, elements left of the zigzag line are metals. To the right of the line we find nonmetals, including the noble gases. Some elements adjacent to the line are called metalloids.

  40. The Modern Periodic Table 40 -In the modern periodic table , the known elements are arranged in order of increasing atomic numbersfrom left to right and from top to bottom in groups. -Elements in the same vertical group are closely resembled one another .(elements in the same vertical group are alike in the physical and chemical properties)

  41. The Modern Periodic Table 41 The modern Periodic Table consists of : - Seven horizontal lines( rows ) of elements called Periods. - Eight vertical columns called Groups or Families. - more than 37 transition elements of the type(d), in ten groups at the middle of table. - 28 transition elements of the type (f) , in two series each with 14 elements : Lanthanide series and Actinide series are located at bottom of the table.

  42. Main Elements and TransitionElements 42 • The elements of the periodic table are two types: • - Main Elements :where the electrons fill the outer shell orbitals of the types s and p . • -The Aqueous solutions of the compounds of the main elements are colorless . • - Transition Elements: where the electrons fill inner shell orbitals of the types d and f . • -The Aqueous solutions of the transition elements compounds have distinguish colors and form metal complexes.

  43. Metals , Nonmetals and Metalloids 43 The Octet Rule in Elements All Elements tend to have eight electrons in their outer shell , or the outer shell electron configuration of the nearest noble gas , either by losing one electron (or more) or by gaining one electron (or more) , or by sharing electrons.

  44. Metals , Nonmetals and Metalloids 44 • - Metals : • Are the elements which tend to lose one electron or more to form positive ions . • Na → Na⁺ + e • Ca → Ca⁺⁺ + 2e • Metals form about 75% of elements. • Metallic properties: increase when we move from right to left , and from top to the bottom in the periodic table. • Metals have a characteristic luster and generally are good conductors of heat and electricity , metals are malleable.

  45. Metals , Nonmetals and Metalloids 45 • -Nonmetals : • Are the elements which tend to gain one electron or more to form negative ions. • Cl + e → Cl⁻ • O + 2e → O⁻⁻ • The nonmetallic properties: increase when we move in the periodic table ,from left to right and from bottom to the top. • Nonmetals are generally are poor conductors of heat and electricity , some are gasses and some are brittle solids.

  46. Metals , Nonmetals and Metalloids 46 • -Metalloids : • Are the elements which display the properties of metals and nonmetals. • The metalloids located :at the center of the periodic table , between the metals and nonmetals elements. • In some groups: we can find metals and nonmetals in the same column , and the metalloids in between. • Example: • In group 4 , carbon C and silicon Si at the top of the group , are nonmetals , while tin Sn and lead Pb in the bottom are metals, germanium Ge in between is a metalloid.

  47. Ions and Ionic Compounds 47 Atoms that gain electrons form anions Cl + e– Cl– EOS The Ion: Is an atom or a group of atoms having negative or positive charges. The Positive ions are called: CATIONS The negative ions are called: ANIONS Atoms that lose electrons form cations Na Na+ + e–

  48. Ions and Ionic Compounds 48 The Ionic Compounds : Are the compounds formed by oppositely charged ions , linked by the electrical attractive forces. (in the ionic compounds there is no net charge) Ionic Bond: It is the bond which is formed by the electrostatic attraction forces between two oppositely charged ions. Binary Ionic Compound: It is the ionic compound which is composed of two kinds of atoms. EOS

  49. Nomenclature: is the method for naming compounds and writing formulas for compounds. We could have a specific name for each compound—but we would have to memorize each one! -Can you imagine having to memorize the names of half a million different inorganic compounds? Twenty million organic compounds?? -Instead we have a systematic method— conventions and rules—for naming compounds and writing formulas. Nomenclature 49

  50. Ions and ionic compounds Binary Ionic Compounds: Sodium chloride :NaCl Potassium Bromide: KBr Calcium Iodide: CaI₂ Barium Oxide: BaO Cobalt(lll) fluoride: CoF₃ Sodium sulphide: Na₂S Aluminum Phosphide: AlP

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