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CHEMISTRY The Molecular Science Chapter two

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Electrical charges of the same type repel one another, ... actinium series trans-uranium series. Types of Elements. metals. nonmetals. metalloids semimetals ... – PowerPoint PPT presentation

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Title: CHEMISTRY The Molecular Science Chapter two


1
CHEMISTRYThe Molecular ScienceChapter two
  • Slides prepared by
  • S. Michael Condren
  • Department of Chemistry
  • Christian Brothers University

to Accompany CHEMISTRY The Molecular Science by
John W. Moore, Conrad Stanitski, Peter C. Jurs
2
Chapter 2
  • Elements Atoms

3
Atomic Structure
  • Electrical charges of the same type repel one
    another, and charges of the opposite type attract
    one another.

4
Radioactivity
5
Alpha Radiation
  • composed of 2 protons and 2 neutrons
  • thus, helium-4 nucleus
  • 2 charge
  • mass of 4 amu
  • creates element with atomic number 2 lower

6
Beta Radiation
  • composed of a high energy electron which was
    ejected from the nucleus
  • neutron converted to proton
  • very little mass
  • -1 charge
  • creates element with atomic number 1 higher

7
Gamma Radiation
  • nucleus has energy levels
  • energy released from nucleus as the nucleus
    changes from higher to lower energy levels
  • no mass
  • no charge

8
Structure of the Atom
  • electrons
  • found in electron cloud
  • relative charge of -1
  • relative mass of 0.00055 amu
  • protons
  • found in nucleus
  • relative charge of 1
  • relative mass of 1.0073 amu
  • neutrons
  • found in nucleus
  • neutral charge
  • relative mass of 1.0087 amu

9
Millikans Experiment
10
Rutherfords Experiment
11
Rutherfords Model of the Atom
  • atom is composed mainly of vacant space
  • all the positive charge and most of the mass is
    in a small area called the nucleus
  • electrons are in the electron cloud surrounding
    the nucleus

12
Ions
  • charged single atom
  • charged cluster of atoms

13
Ions
  • cations
  • positive ions
  • anions
  • negative ions
  • ionic compounds
  • combination of cations and anions
  • zero net charge

14
Metric Prefixes
15
Relative size of atom and atomic nucleus
16
Scanning Tunneling Microscope
17
Measurement and Units
  • length - meter
  • volume - liter
  • mass - gram

18
Atomic number, Z
  • the number of protons in the nucleus
  • the number of electrons in a neutral atom
  • the integer on the periodic table for each element

19
Isotopes
  • atoms of the same element which differ in the
    number of neutrons in the nucleus
  • designated by mass number

20
Isotopes of Hydrogen H-1, 1H, protium
  • 1 proton and no neutrons in nucleus
  • only isotope of any element containing no
    neutrons in the nucleus
  • most common isotope of hydrogen

21
Isotopes of Hydrogen H-2 or D, 2H, deuterium
  • 1 proton and 1 neutron in nucleus

22
Isotopes of Hydrogen H-3 or T, 3H, tritium
  • 1 proton and 2 neutrons in nucleus

23
Mass Number, A
  • integer representing the approximate mass of an
    atom
  • equal to the sum of the number of protons and
    neutrons in the nucleus

24
Nuclear Notation
  • X-A
  • C-12
  • XA
  • C12
  • ZXA
  • 6C12

25
Masses of Atoms
  • Carbon-12 Scale
  • Masses of the atoms are compared to the mass of
    C-12 isotope having a mass of 12.0000

26
Mass Spectrometer
27
Atomic Masses andIsotopic Abundances
  • natural atomic masses
  • sum(atomic mass of isotope)
  • ? (fractional isotopic abundance)

28
The Mole
  • a unit of measurement, quantity of matter present
  • Avogadros Number
  • 6.022 ? 1023 particles
  • Latin for pile

29
Molar Mass
  • Sum
  • atomic masses
  • represented by formula
  • atomic masses ? gaw
  • molar mass ? MM

30
Example
  • How many grams of Cu are there in 5.67 mol Cu?
  • g Cu (5.67 mol)(63.546g/mol)
  • 360. g

Atomic mass of Cu
31
Example
  • Calculate the number of boron atoms in 1.000g
    sample of the element.
  • B atoms (1.000g)(1mol / 10.81g)
  • ? (6.022 ? 1023atoms/mol)
  • 5.571 ? 1022 B atoms

32
Example
  • How many moles of silicon, S, are in 30.5g of S?
  • mol Si (30.5g)(1 mol/32.06g)
  • 0.951 mol Si

33
Example
  • What is the molar mass of methanol, CH3OH?
  • MM 1(gaw)C (3 1)(gaw)H 1(gaw)O
  • 1(12.011)C 4(1.00794)H 1(15.9994)O
  • 22.042 g/mol

34
Example
  • How many moles of carbon dioxide molecules are
    there in 6.45g of carbon dioxide?
  • MM 1(gaw)C 2(gaw)O 44.01 g/mol
  • mol CO2 (6.45g)(1 mol/44.01g)
  • 0. 147 mol

35
Development of Periodic Table
  • Newlands - English
  • 1864 Law of Octaves every 8th element
    has similar properties

36
Development of Periodic Table
  • Mendeleev
  • Russian
  • 1869 - Periodic Law
  • allowed him to predict properties of unknown
    elements

37
Mendeleevs Periodic Table
  • the elements are arranged according to
    increasing atomic weights
  • Missing elements 44, 68, 72, 100 amu

38
Predicted Properties of Ekasilicon
39
Modern Periodic Table
  • Moseley, Henry Gwyn Jeffreys
  • 18871915, English physicist.
  • studied the relations among spectra of different
    elements.
  • concluded that the atomic number is equal to the
    charge on the nucleus based on the x-ray spectra
    emitted by the element.
  • explained discrepancies in Mendeleevs Periodic
    Law.

40
Modern Periodic Table
  • the elements are arranged according to increasing
    atomic numbers

41
Periodic Table of the Elements
42
Organization of Periodic Table
  • period horizontal row
  • group vertical column

43
Family Names
  • Group IA alkali metals
  • Group IIA alkaline earth metals
  • Group VIIA halogens
  • Group VIIIA noble gases
  • transition metals
  • inner transition metals
  • lanthanum series rare earths
  • actinium series trans-uranium series

44
Types of Elements
  • metals
  • nonmetals
  • metalloids semimetals
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