Chapter 2.powerpoint
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1) Atoms are made up of protons, neutrons, and electrons. The atomic number is the number of protons, and the mass number is the total number of protons and neutrons. Isotopes are atoms of the same element that differ in their number of neutrons. 2) Molecules are two or more atoms bonded together, while ions are atoms or groups of atoms with a positive or negative charge. Polyatomic ions and molecules contain more than one atom. 3) Chemical formulas indicate the composition of substances. Molecular formulas show exact atom counts, empirical formulas are the simplest whole number ratios, and ionic formulas result in an overall neutral charge. Nomenclature provides systematic names for compounds.
Chapter 2.powerpoint
- 1. Atoms, Molecules and Ions Chapter 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 3. mass p = mass n = 1840 x mass e- 2.2
- 4. Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes are atoms of the same element (X) with different numbers of neutrons in their nuclei XA Z H1 1 H (D)2 1 H (T)3 1 U235 92 U238 92 Mass Number Atomic Number Element Symbol 2.3 Atomic number, Mass number and Isotopes
- 5. 2.3 The Isotopes of Hydrogen
- 6. 6 protons, 8 (14 - 6) neutrons, 6 electrons 6 protons, 5 (11 - 6) neutrons, 6 electrons Do You Understand Isotopes? 2.3 How many protons, neutrons, and electrons are in C 14 6 ? How many protons, neutrons, and electrons are in C 11 6 ?
- 10. Chemistry In Action Natural abundance of elements in Earth’s crust Natural abundance of elements in human body 2.4
- 11. 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 A polyatomic molecule contains more than two atoms O3, H2O, NH3, CH4 2.5
- 12. 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. anion – ion with a negative charge If a neutral atom gains one or more electrons it becomes an anion. Na 11 protons 11 electrons Na+ 11 protons 10 electrons Cl 17 protons 17 electrons Cl- 17 protons 18 electrons 2.5
- 13. A monatomic ion contains only one atom A polyatomic ion contains more than one atom 2.5 Na+, Cl-, Ca2+, O2-, Al3+, N3- OH-, CN-, NH4 +, NO3 -
- 14. 13 protons, 10 (13 – 3) electrons 34 protons, 36 (34 + 2) electrons Do You Understand Ions? 2.5 How many protons and electrons are in ?Al27 13 3+ How many protons and electrons are in ?Se78 34 2-
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- 17. A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance An empirical formula shows the simplest whole-number ratio of the atoms in a substance H2OH2O molecular empirical C6H12O6 CH2O O3 O N2H4 NH2 2.6
- 18. 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 The ionic compound NaCl 2.6
- 19. Formula of Ionic Compounds Al2O3 2.6 2 x +3 = +6 3 x -2 = -6 Al3+ O2- CaBr2 1 x +2 = +2 2 x -1 = -2 Ca2+ Br- Na2CO3 1 x +2 = +2 1 x -2 = -2 Na+ CO3 2-
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- 21. 2.7
- 22. Chemical Nomenclature • Ionic Compounds – often a metal + nonmetal – anion (nonmetal), add “ide” to element name BaCl2 barium chloride K2O potassium oxide Mg(OH)2 magnesium hydroxide KNO3 potassium nitrate 2.7
- 23. • Transition metal ionic compounds – indicate charge on metal with Roman numerals FeCl2 2 Cl- -2 so Fe is +2 iron(II) chloride 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
- 24. • Molecular compounds • nonmetals or nonmetals + metalloids • common names • H2O, NH3, CH4, C60 • element further left in periodic table is 1st • element closest to bottom of group is 1st • if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom • last element ends in ide 2.7
- 25. HI hydrogen iodide NF3 nitrogen trifluoride SO2 sulfur dioxide N2Cl4 dinitrogen tetrachloride NO2 nitrogen dioxide N2O dinitrogen monoxide Molecular Compounds 2.7 TOXIC! Laughing Gas
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- 27. An acid can be defined as a substance that yields hydrogen ions (H+) when dissolved in water. HCl •Pure substance, hydrogen chloride •Dissolved in water (H+ Cl-), hydrochloric acid An oxoacid is an acid that contains hydrogen, oxygen, and another element. HNO3 nitric acid H2CO3 carbonic acid H2SO4 sulfuric acid 2.7HNO3
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- 31. A base can be defined as a substance that yields hydroxide ions (OH-) when dissolved in water. NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 barium hydroxide 2.7
- 32. Hydrates are compounds that have a specific number of water molecules attached to them. BaCl2•2H2O 2.7 LiCl•H2O MgSO4•7H2O Sr(NO3)2 •4H2O barium chloride dihydrate lithium chloride monohydrate magnesium sulfate heptahydrate strontium nitrate tetrahydrate CuSO4•5H2O CuSO4
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- 34. Organic chemistry is the branch of chemistry that deals with carbon compounds C H H H OH C H H H NH2 C H H H C OH O methanol methylamine acetic acid 2.7 Functional Groups