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

Dalton’s Atomic Theory (1808) 1. ____________are composed of extremely small particles called atoms. 2.All ____________of a given element are identical, having the same size, mass and chemical properties. The atoms of one element are different from the atoms of all other elements. 3._________________________are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction. 4.A __________ __________ involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction. 2.1

2 Dalton’s Atomic Theory

8 X 2 Y 16 X8 Y + 2.1

J.J. Thomson, measured mass/charge of e - (1906 Nobel Prize in Physics) 2.2

Cathode Ray Tube 2.2

e - charge = x C Thomson’s charge/mass of e - = x 10 8 C/g e - mass = 9.10 x g Measured mass of e - (1923 Nobel Prize in Physics) 2.2

(Uranium compound) 2.2

1.atoms positive charge is concentrated in the nucleus 2.proton (p) has opposite (+) charge of electron (-) 3.mass of p is 1840 x mass of e - (1.67 x g)  particle velocity ~ 1.4 x 10 7 m/s (~5% speed of light) (1908 Nobel Prize in Chemistry) 2.2

atomic radius ~ 100 pm = 1 x m nuclear radius ~ 5 x pm = 5 x m Rutherford’s Model of the Atom 2.2 “If the atom is the Houston Astrodome, then the nucleus is a marble on the 50-yard line.”

Chadwick’s Experiment (1932) (1935 Noble Prize in Physics) H atoms - 1 p; He atoms - 2 p mass He/mass H should = 2 measured mass He/mass H = 4  + 9 Be 1 n + 12 C + energy neutron (n) is neutral (charge = 0) n mass ~ p mass = 1.67 x g 2.2

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

__________ __________ (Z) = number of protons in nucleus _______ _______(A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons __________ are atoms of the same element (X) with different numbers of neutrons in their nuclei X A Z H 1 1 H (D) 2 1 H (T) 3 1 U U Mass Number Atomic Number Element Symbol 2.3 Atomic number, Mass number and Isotopes

2.3 The _________________ of Hydrogen

__ protons, __ (14 - 6) neutrons, __ electrons __ protons, __ (11 - 6) neutrons, __ 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 ?

Period Group Alkali Metal Noble Gas Halogen Alkali Earth Metal 2.4

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

A __________ is an aggregate of two or more atoms in a definite arrangement held together by chemical forces H2H2 H2OH2ONH 3 CH 4 A ________ __________ contains only two atoms H 2, N 2, O 2, Br 2, HCl, CO A _________ ________ contains more than two atoms O 3, H 2 O, NH 3, CH 4 2.5

An _______________is an atom, or group of atoms, that has a net positive or negative charge. ____________ – ion with a positive charge If a neutral atom ______ one or more electrons it becomes a cation. ____________ – ion with a negative charge If a neutral atom ______ 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

A __________ ion contains only one atom A __________ ion contains more than one atom 2.5 Na +, Cl -, Ca 2+, O 2-, Al 3+, N 3- OH -, CN -, NH 4 +, NO 3 -

___ protons, ___ (13 – 3) electrons ___ protons, ___ (34 + 2) electrons Do You Understand Ions? 2.5 How many protons and electrons are in ?Al How many protons and electrons are in ?Se

Some Polyatomic Ions 2.7

2.5

2.6

A __________ formula shows the exact number of atoms of each element in the smallest unit of a substance An __________ formula shows the simplest whole-number ratio of the atoms in a substance H2OH2O H2OH2O molecularempirical C 6 H 12 O 6 CH 2 O O3O3 O N2H4N2H4 NH 2 2.6

__________ 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

Formula of Ionic Compounds Al 2 O x +3 = +63 x -2 = -6 Al 3+ O 2- CaBr 2 1 x +2 = +22 x -1 = -2 Ca 2+ Br - Na 2 CO 3 1 x +2 = +21 x -2 = -2 Na + CO 3 2-

2.7

Chemical Nomenclature Ionic Compounds –often a metal + nonmetal –anion (nonmetal), add “ide” to element name BaCl 2 barium chloride K2OK2O potassium oxide Mg(OH) 2 magnesium hydroxide KNO 3 potassium nitrate 2.7

Transition metal ionic compounds –indicate charge on metal with Roman numerals FeCl 2 2 Cl - -2 so Fe is +2 _______________ FeCl 3 3 Cl - -3 so Fe is +3 _______________ Cr 2 S 3 3 S so Cr is +3 (6/2)_______________ 2.7

_______________ compounds nonmetals or nonmetals + metalloids common names H 2 O, NH 3, CH 4, C 60 element further left in periodic table is 1 st element closest to bottom of group is 1 st 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

HIhydrogen iodide NF 3 nitrogen trifluoride SO 2 sulfur dioxide N 2 Cl 4 dinitrogen tetrachloride NO 2 nitrogen dioxide N2ON2Odinitrogen monoxide _______________ Compounds 2.7 TOXIC ! Laughing Gas

2.7

An __________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 ___________is an acid that contains hydrogen, oxygen, and another element. HNO 3 nitric acid H 2 CO 3 carbonic acid H 2 SO 4 sulfuric acid 2.7 HNO 3

2.7

A ________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

_________ are compounds that have a specific number of water molecules attached to them. BaCl 2 2H 2 O 2.7 LiClH 2 O MgSO 4 7H 2 O Sr(NO 3 ) 2 4H 2 O barium chloride dihydrate lithium chloride monohydrate magnesium sulfate heptahydrate strontium nitrate tetrahydrate CuSO 4 5H2O CuSO4

2.7

_______________ _______________ is the branch of chemistry that deals with carbon compounds C H H H OH C H H H NH 2 C H H H COH O methanolmethylamineacetic acid 2.7 Functional Groups