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Chapter 2 Atoms, Molecules and Ions

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1 Chapter 2 Atoms, Molecules and Ions
Copyright © The McGraw-Hill Companies, Inc.  Permission required for reproduction or display.

2 Chapter 2 (p.49-68) Atomic number , mass number and isotopes.
The periodic table . Molecules and ions . Chemical formulas . Naming compounds . Tables – 2.3 – – 2.6 – 2.7 Examples – 2.3 – 2.4 – 2.5 – 2.6 – 2.7 – 2.8 – 2.9

3 mass p = mass n = 1840 x mass e- 2.2

4 2.3 Atomic number , mass number and isotopes.

5 Atomic number, Mass number and Isotopes
Atomic number (Z) = number of protons+ number of electrons Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutron Mass Number X A Z Element Symbol Atomic Number H 1 H (D) 2 H (T) 3 U 235 92 238 2.3

6 Do You Understand Isotopes?
How many protons, neutrons, and electrons are in C 14 6 ? 6 protons, 8 (14 - 6) neutrons, 6 electrons How many protons, neutrons, and electrons are in C 11 6 ? 6 protons, 5 (11 - 6) neutrons, 6 electrons Define the element X 63 29 ? The element with atomic number 29 is cupper (Cu) and its mass number is 63 2.3

7 Give the number of protons, neutrons, and electrons
Example 2.1 Give the number of protons, neutrons, and electrons in each of the following species: elements Atomic Number (Z) 11 8 6 80 Mass Number (A) 20 22 17 14 200 No. of electrons (e) No. of protons (p) No. of neutrons (n) 9 120 Na 20 11 Na 22 11 O 17 8 C 14 6 Hg 200 80

8 Isotopes Isotopes are atoms of the same element (X) with different numbers of neutrons (mass number) hydrogen deuterium tritrium 2.3

9

10 Allotropes Allotrope is one of tow or more distinct forms of an element as O2 , O3 . O-O (O2) and O3 Diamond and Graphite

11 Example for Allotropes
Diamond and Graphite

12 Diamond and Graphite Graphite Diamond

13 2.4 The periodic table .

14 Periodic Table Alkali Earth Metal Alkali Metal Noble Gas Group Halogen
2.4

15 Chemistry In Action Natural abundance of elements in Earth’s crust
Natural abundance of elements in human body 2.4

16 2.5 molecules and ions.

17 A diatomic molecule contains only two atoms
The monatomic molecules are the single atoms of noble gases; He, Ne, Ar, Kr, Xe, Rn. A molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical forces. H2 H2O NH3 CH4 A diatomic molecule contains only two atoms H2, N2, O2, Br2, HCl, CO, NO, KCl A polyatomic molecule contains more than two atoms O3, H2O, NH3, CH4, NaOH 2.5

18 cation – ion with a positive charge
An ion is an atom, or group of atoms, that has a net positive or negative charge. cation – ion with a positive charge If a neutral atom loses one or more electrons it becomes a cation. Na 11 protons 11 electrons Na+ 11 protons 10 electrons anion – ion with a negative charge If a neutral atom gains one or more electrons it becomes an anion. Cl- 17 protons 18 electrons Cl 17 protons 17 electrons 2.5

19 A monatomic ion contains only one atom
Na+, Cl-, Ca2+, O2-, Al3+, N3- A polyatomic ion contains more than one atom OH-, CN-, NH4+, NO3- 2.5

20 Do You Understand Ions? How many protons and electrons are in ? Al
27 13 3+ 13 protons, 10 (13 – 3) electrons How many protons and electrons are in ? Se 78 34 2- 34 protons, 36 (34 + 2) electrons 2.5

21 Different Ions of Some Elements
2.5

22 B 11 5 P 31 15 3- Au 196 79 Rn 222 86 26 18-3=15 54-26=28 26-2=24 86 2+

23 2.6 chemical formulas.

24 2.6 الصيغة الجزيئية الصيغة البنائية نموذج الكرة والعصا
نموذج ملء الفراغ 2.6

25 من الصيغة الجزيئية نستطيع إيجاد الصيغة الأولية والعكس غير صحيح
أبسط صورة للجزئ تعطي نسب وجود الذرات المكونة للجزئ بأصغر نسبة وليس من الضروري أن تعطي العدد الصحيح للذرات An empirical formula shows the simplest whole-number ratio of the atoms in a substance الصيغة الجزيئية تحتوي على العدد الصحيح من ذرات كل عنصر يدخل في تركيب أصغر وحده في المادة (الجزئ) من الصيغة الجزيئية نستطيع إيجاد الصيغة الأولية والعكس غير صحيح A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance H2O molecular empirical H2O C6H12O6 CH2O O3 O N2H4 NH2 2.6

26

27 Write the Molecular formula of Methanol and Chloroform, using the structural formulas below:
Cl H Molecular formula of Methanol Molecular formula of Chloroform CH4O CHCl3 or CH3OH

28

29 acetylene C2H2 CH glucose C6H12O6 CH2O nitrous oxide N2O caffeine
Write the empirical formulas for the following molecules if possible: Compounds Name Molecular Formula Empirical Formula acetylene C2H2 CH glucose C6H12O6 CH2O nitrous oxide N2O caffeine C8H10N4O2 C4H5N2O

30 The ionic compound NaCl
ionic compounds consist of a combination of cations and an anions the formula is always the same as the empirical formula the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero المركبات الأيونية صيغتها الجزيئية مطابقة للصيغة الأولية مجموع الكاتيونات + الأنيونات = صفر The ionic compound NaCl 2.6

31 Formula of Ionic Compounds
2 x +3 = +6 3 x -2 = -6 Al2O3 Al3+ O2- 1 x +2 = +2 2 x -1 = -2 CaBr2 Ca2+ Br- 2 x +1 = +2 1 x -2 = -2 Na2CO3 Na+ CO32- 2.6

32

33 1. An anion is defined as  A. a charged atom or group of atoms with a net negative charge. B. a stable atom. C. a group of stable atoms. D. an atom or group of atoms with a net positive charge. 2. Atoms of the same element with different mass numbers are called  A. ions. B. neutrons. C. allotropes. D. chemical families. E. isotopes. 3. How many neutrons are there in an atom of lead 82Pb whose mass number is 208?  A. 82 B. 126 C. 208 D. 290 E. none of them

34 4. An atom of the isotope sulfur-31 consists of how many protons, neutrons, and electrons? (p = proton, n = neutron, e = electron)  A. 15 p, 16 n, 15 e B. 16 p, 15 n, 16 e C. 16 p, 31 n, 16 e D. 32 p, 31 n, 32 e E. 16 p, 16 n, 15 e 5. A magnesium ion, Mg2+, has  A. 12 protons and 13 electrons. B. 24 protons and 26 electrons. C. 12 protons and 10 electrons. D. 24 protons and 22 electrons. E. 12 protons and 14 electrons. 6. A sulfide ion, S2- , has:  A. 16 protons and 16 electrons B. 32 protons and 16 electrons C. 16 protons and 14 electrons D. 16 protons and 18 electrons E. 32 protons and 18 electrons

35 Answer Key 1-A 2-E 3-B 4-B 5-C 6-D
Problems 2.10 – 2.11 – 2.12 – 2.14 – 2.16 – 2.18 – 2.36 – 2.44 – 2.46 – 2.50

36 2.7 naming compounds.

37 Chemical Nomenclature
المركبات الأيونية يتكون الإسم من الفلز يلية اللافلز يضاف ide لللافلز Ionic Compounds often a metal + nonmetal anion (nonmetal), add “ide” to element name Binary compounds are compounds formed from just two elements BaCl2 barium chloride K2O potassium oxide Ternary compounds are compounds formed from three elements. Mg(OH)2 magnesium hydroxide KNO3 potassium nitrate 2.7

38 Chemical Nomenclature of
Ionic Compounds Metal (cation) nonmetal (anion)

39 Metal (cation) Transition metals Monovalent elements Divalent elements
trivalent elements Transition metals Lithium (Li+) Sodium (Na+) Potassium (K+) Robidium (Rb+) Silver (Ag+) Magnisium (Mg2+) Calcium (Ca2+) Strontium (Sr2+) Barium (Ba2+) Lead (Pb2+) Zinc (Zn2+) Aluminium (Al3+) Galium (Ga3+) (Fe2+) iron(II) (Fe3+) iron(III) (Cr3+) chromium (III) (Cu2+) cupper (II) (Cu+) cupper (I) (Mn2+) manganese(II) (Mn3+) manganese(III) (Mn4+) manganese(IV) (Mn7+) manganese(VII) (Sn2+) stannous or tin(II) (Hg22+) mercury(I) (Hg2+) mercury(II)

40 nonmetal (anion) Hydrogen hydride (H-) Oxygen oxide (O2-)
Nitrogen nitride (N3-)

41 Some common oxygenated anions
(SO42-) sulphate , (SO32-) sulphite (HSO4-) hydrogen sulphate or bisulphate (PO43-) phosphate (PO33- ) phosphite (HPO42-) hydrogen phosphate (H2PO4-) dihydrogen phosphate (NO3-) nitrate (NO2-) nitrite (ClO4– ) chlorate (ClO3- ) chlorite (CO32–) carbonate (HCO3– ) bicarbonate

42 2.7

43 Transition metal ionic compounds
indicate charge on metal with Roman numerals In the Stock system the different cations charge are designated with Roman numerals FeCl2 iron(II) chloride 2 Cl- -2 so Fe is +2 FeCl3 3 Cl- -3 so Fe is +3 iron(III) chloride Cr2S3 3 S-2 -6 so Cr is +3 (6/2) chromium(III) sulfide 2.7

44

45 Potassium dihydrogen phosphate
Name the following ionic compounds: Cu(NO3)2 Cupper(II) nitrate KH2PO4 Potassium dihydrogen phosphate NH4SCN Ammonium thiocyanate H2O2 Hydrogen peroxide Li2SO3 Lithium sulphite Ca3(PO3)2 Calcium phosphite KMnO4 Potassium permenganate Hg2Cl2 Mercury(I) chloride K2CrO4 Potassium chromate Br2O7 Dibromine heptoxide

46 Potassium hydrogen phosphate K2HPO4
Write formulas for the following ionic compounds: Manganese(II) oxide MnO Potassium hydrogen phosphate K2HPO4 NH4ClO2 Ammonium chlorite Lead hydroxide Pb(OH)2 Sodium bicarbonate NaHCO3 Barium cyanide Ba(CN)2 RbHSO4 Rubidium hydrogensulphate Mercury(II) bromide HgBr2 Strontium hydride SrH2

47 Molecular Compounds 1- Consists of (metalloids + nonmetals)
Or (nonmetal + nonmetal) 2- common names of some molecular compounds Diborane B2H6 Methane CH4 Silane SiH4 Ammonia NH3 Phosphine PH3 Water H2O Hydrogen sulfide H2S المركبات الجزيئية تتكون من أشباه فلزات + لا فلزات لا فلزات + لا فلزات بعضها له أسماء شائعه مثل H2O, NH3, CH4 العنصر الأخير يضاف لنهايته ide 6- last element ends in -ide

48 4- element closest to bottom of group is 1st (less electronegative)
3- element further left in periodic table is 1st (less electronegative) (HCl) H(1A) and Cl(7A), so hydrogen is 1st, the name is hydrogen chloride تكتب العناصر الموجوده يسار الجدول الدوري أو الأقرب لليسار أولا. المركبات المحتوية على أكثر من ذرة من نفس العنصر يعبر عن عدد الذرات للعنصر لها باستخدام البادئات اليونانية 4- element closest to bottom of group is 1st (less electronegative) (SiC) Si(4A) and C also belongs to (4A) ,but (Si) is closest to bottom of the group, so silicon is 1st , the name is silicon carbide 5- if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom. (NO) nitrogen monooxide (NO2) nitrogen dioxide (N2O) dinitrogen monooxide 2.7

49 Examples of Molecular Compounds
HI hydrogen iodide PF3 phosphorus trifluoride H2O2 Hydrogen peroxide N2O4 dinitrogen tetraoxide TOXIC! NO2 nitrogen dioxide N2O dinitrogen monooxide Laughing Gas ICl3 Iodine trichloride 2.7

50 Name the following molecular compounds:
SO2 Sulpher dioxide SiCl4 Silicon tetrachloride BrF7 Bromine heptaflouride P4O10 Tetraphosphorus decoxide Cl2O7 Dichlorine heptoxide CH4 Methane CS2 Carbon disulphide Br2O7 Dibromine heptoxide

51 Sulphur tetraflouride SF4
Write formulas for the following molecular compounds: Sulphur tetraflouride SF4 Dinitrogen pentoxide N2O5 Sulfur trioxide SO3 Disilicon hexabromide Si2Br6 Phosphorus pentachloride PCl5 Tetraphosphorus decasulphide P4S10 Nitrogen peroxide N2O2 Carbon monoxide CO Iodine heptaflouride IF7

52 Fill the blanks in the following table
name formula anion cation Barium bicarbonate Ba(HCO3)2 HCO3- Ba2+ Iron(III)nitrite Fe (NO2)3 NO2- Fe3+ Hyrdogen flouride HF F- H+ Manganise(IV)oxide MnO2 O2- Mn4+ Sodium peroxide Na2O2 O22- Na+ Cesium chlorate CsClO3 ClO3- Cs+ Lithium nitride Li3N N3- Li+

53 7. Which compound has the same empirical formula as C6H12O6? A) C12H24O12 B) C3H3O3 C) CH2ON D) CHO2 8. Which of the following compounds is named lithium carbonate? A) Na2CO3 B) LiHCO3 C) LiCO D) Li2CO3 9. What is the formula for ammonium sulfate? A) NH4SO4 B) NH4(SO4)2 C) (NH4)2SO4 D) NH4S

54 Answer Key 7-A D C Problems 2.58 – 2.60 – 2.94


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