Chapter Three

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Chapter Three

• Atomic Structure and the Periodic Table

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Atomic Structure and the Periodic Table contd

• Recall our understanding of an element.
• Element is matter that ______ be broken down into
  a simpler substance by ________ or _________
  means.
• Recall our understanding of an atom.
• Atom is the ________ particle of an element that
  can exist and still have the properties of the
  element.

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Atomic Structure and the Periodic Table contd

• Now we will discuss ATOMIC STRUCTURE and
  Sub-Atomic Particles
• An atom is composed of a _______ and an area
  called the electron _____
• The nucleus is very small compared to the size of
  the atom
• The nucleus contains the _______ () and the
  _______
• The __________ (-) are constantly moving around
  in the electron cloud
• In a neutral atom, the number of electrons (-) is
  _______ to the number of protons ()

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Atomic Structure and the Periodic Table contd

• Fig. 3.1 Nuclear Model of the Atom
• The protons and neutrons of an atom are found in
  the central nuclear region, or nucleus, and the
  electrons are found in an electron cloud outside
  the nucleus.

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Atomic Structure and the Periodic Table contd
Electron Proton Neutron
Charge -1 1 0
Actual Mass (g) 9.109 X 10-28 1.673 X 10-24 1.675 X 10-24
Relative Mass e 1 mass unit 1 1837 1839
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Atomic Structure and the Periodic Table contd

• Atomic Symbols

Charge number of protons number of electrons
Mass number number of protons number of
neutrons
Q
A
X
Z
Atomic number number of protons
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Atomic Structure and the Periodic Table contd

• _________ Atomic Number Z
• Atoms have no charge,
• __________ __________ Z
• Neutrons ______ Number (A) - _________ (Z)

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Atomic Structure and the Periodic Table contd

• Electrons are arranged around the nucleus of an
  atom
• Electrons can be _____ to, _______ from or
  _______ with other atoms
• When lost or gained, atoms become _______ (ions)
• Lost electrons result in _____charged ion,
  ________
• Gained electrons result in _____ charged ion,
  _____
• Protons in nucleus ________ changes, _________
  arrangement determine chemical properties

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Atomic Structure and the Periodic Table contd

• Atomic Symbol vs Periodic Table

20 Ca 40.08
2
40
Ca
20
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Atomic Structure and the Periodic Table contd

• How many electrons, neutrons, and protons are in
  the following particles?

protons electrons neutrons
40Ca
40Ca2
14C
12C
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Atomic Structure and the Periodic Table contd

• Protons remains constant
• Neutrons can vary
• Mass numbers of atoms of same element will vary
  depending on the neutrons in the nucleus
• Atoms that differ in neutrons are called
  Isotopes

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Atomic Structure and the Periodic Table contd

• Most elements have naturally occurring __________
• Number of isotopes can range from two to ten
• Example Silicon, Si exists in three isotopic
  forms
• All Si atoms have 14 protons and 14 electrons
• Most, 92.21 contain 14 neutrons
• Some, 4.70 contain 15 neutrons
• Some, 3.09 contain 16 neutrons

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Atomic Structure and the Periodic Table contd

• They have the following notations

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28
30
Si
Si
Si
14
14
14
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Atomic Structure and the Periodic Table contd

• The additional neutrons in the nucleus may have
  very slight effects on the chemical properties of
  the element, and some measurable effects on some
  physical properties such as melting points,
  boiling points and Densities. See Chemical
  Connections on pg 55 in text.

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Atomic Structure and the Periodic Table contd

• The atomic mass is expressed in atomic mass units
• amu
• atomic mass unit
• Defined as 1/12th the mass of 12C
• 1 amu the mass of 1 proton or 1 neutron
• The atomic mass that is found on the periodic
  table or used for calculations is a weighted
  average of the atomic masses for the isotopes

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Atomic Structure and the Periodic Table contd

• To get the average mass of an element, you must
  add together the mass contributions of each
  different isotope
• abundance x isotopic mass mass contribution
• Calculate the average atomic mass of Chlorine if
  75.53 of the atoms are 35Cl (34.97 amu) and
  24.47 of the atoms are 37Cl (36.97 amu).
• (0.7553 x 34.97 amu) (0.2447 x 36.97 amu)
• 35.46 amu

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Atomic Structure and the Periodic Table contd
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Atomic Structure and the Periodic Table contd

• Table 3.2
• Isotopic Data for Elements with Atomic Numbers
  1 through 12

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Atomic Structure and the Periodic Table contd

• Early 1800s, scientists searched for some order
  in the chemical information known at that time
• Certain elements had properties that were very
  similar to those of other elements
• Method or Arrangement was sought that would be
  consistent with this information

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Atomic Structure and the Periodic Table contd

• John Newlands (1865)
• Arranged elements in order of increasing atomic
  mass
• When he did this, he noticed that there were
  chemical and physical properties that repeated
  every eight elements
• law of octaves

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Atomic Structure and the Periodic Table contd

• Fig. 3.2
• Mendeleev constructed a periodic table as part
  of his effort to systemize chemistry.

Edgar Fahs Smith Collection, University of
Pennsylvania Library
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Atomic Structure and the Periodic Table contd

• Dmitri Mendeleev and Julius Lothar Meyer
  independently proposed ideas or relationships
  regarding the periodicity of __________ and
  increasing atomic ________ or atomic _________.
• Modern Periodic Law states that when elements are
  arranged in order of increasing atomic number,
  elements with similar chemical properties occur
  at periodic or regularly recurring intervals.

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Atomic Structure and the Periodic Table

• CO 3.1
• Music consists of a series of tones that build
  octave after octave. Similarly, elements have
  properties that recur period after period.

Novastock/PhotoEdit
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Atomic Structure and the Periodic Table contd

• Elements with similar chemical properties are
  positioned in _________ ___________
• These _________ _________ are called ________
• The ____________ ______ of elements are called
  ____________
• Note the _________ are numbered sequentially 1-7
• The ________ are identified by two notations,
  using Roman numerals and letters, or numbered
  sequentially 1-18

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Atomic Structure and the Periodic Table contd

• Also note that Element 72 follows Element 57, as
  does Element 104 follows Element 89
• The missing elements 58 through 71 and 90 through
  103 are located in two rows at the bottom of the
  periodic table.
• Positioned here for convenience.
• See the periodic table in the next slide with
  these rows positioned where they should be
  located.

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Atomic Structure and the Periodic Table contd

• Fig. 3.4
• In this periodic table, elements 58 through 71
  and 90 through 103 are shown in their proper
  positions.

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Atomic Structure and the Periodic Table contd

• Common Names for some Groups
• Group IA Alkali Metals, excluding H
• Soft, shiny and readily react with water
• Group IIA Alkaline earth metals
• Soft, shiny and moderately reactive toward water
• Group VIIA Halogens
• Reactive, colored, gases at or slightly above
  room temperatures
• Group VIII Nobel Gases
• Generally unreactive, that undergo few, if any,
  chemical reactions

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Atomic Structure and the Periodic Table contd
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Atomic Structure and the Periodic Table contd
Fig. 3.5

1. Some familiar metals are aluminum, lead, tin, and
   zinc.

(b) Some familiar nonmetals are sulfur,
phosphorus, and bromine.
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Atomic Structure and the Periodic Table contd

• Fig. 3.6
• This portion of the periodic table shows the
  dividing line between metals and nonmetals.

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Atomic Structure and the Periodic Table contd

• Electrons are arranged around the nucleus of an
  atom
• Electrons can be lost to, gained from or shared
  with other atoms
• When lost or gained, atoms become charged (ions)
• Lost electrons result in charged ion, cation
• Gained electrons result in charged ion, anion
• Inference Electrons are special and we will
  learn are related to the chemical properties of
  an element

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Atomic Structure and the Periodic Table contd

• The space outside the nucleus in an atom is
  called the ___________ ____________
• The _________ ________ is subdivided into
  different ___________ (positioned according to
  energy each electron possesses
• Shells are subdivided into ____________
• Subshells are subdivided into __________
• Each orbital contains _____ electrons

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Atomic Structure and the Periodic Table contd

• Electron Shell
• A region of space about a nucleus that contains
  electrons that have approximately the same energy
  and that spend most of their time approximately
  the same distance from the nucleus
• 1st shell
• Can contain up to 2 electrons
• 2nd shell
• Can contain up to 8 electrons
• 3rd shell
• Can contain up to 18 electrons
• 4th shell
• Can contain up to 32 electrons
• Any shell can contain up to 2n2 electrons, where
  n is the shell number

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Atomic Structure and the Periodic Table contd

• Subshell
• A region of space within an electron shell that
  contains electrons that have the same __________
• Four different kinds of subshells s, p, d, and
  f
• Shell 1 contains s subshell
• Shell 2 contains s and p subshells
• Shell 3 contains s, p, and d subshells
• Shell 4 contains s, p, d, and f subshells

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Atomic Structure and the Periodic Table contd

• Fig. 3.7
• The number of subshells within a shell is equal
  to the shell number.

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Atomic Structure and the Periodic Table contd

• Orbital
• Region of space where two electrons are found
• Have different shapes depending on which subshell
  they are in (shape of region of space not
  electrons)
• There are a different number of orbitals in each
  kind of subshell
• In an s subshell, there is 1 orbital
• In a p subshell, there are 3 orbitals
• In a d subshell, there are 5 orbitals
• In a f subshell, there are 7 orbitals

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Atomic Structure and the Periodic Table contd

• Fig. 3.8
• An s orbital has spherical shape a p orbital
  has two lobes a d orbital has four lobes and an
  f orbital has eight lobes.

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Atomic Structure and the Periodic Table contd

• Fig. 3.9
• Orbitals within a subshell differ mainly in
  orientation.

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Atomic Structure and the Periodic Table contd

• There are ____ electrons in each ________
• The electrons move around in the __________
• One of the electrons spins __________
• One of the electrons spins ______________________

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Atomic Structure and the Periodic Table contd

• Electron configurations tells us in which
  subshells the electrons for an element are
  located.
• Three rules
• 1. Electrons fill orbitals starting with lowest
  energy first
• 2. There can be no more than 2 electrons in any
  orbital, and those electrons must have different
  spins
• 3. For orbitals in the same subshell, electrons
  fill each orbital singly before any orbital gets
  a second electron

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Atomic Structure and the Periodic Table contd

• Fig. 3.10
• The order of filling various electron subshells.
  Subshells of different shells overlap.
• How will you remember the order?

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Atomic Structure and the Periodic Table contd

• Fig. 3.11
• The order of filling various electron subshells
  with electrons follows the same order given by
  the arrows in this diagram.

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Atomic Structure and the Periodic Table contd

• Writing Electronic Configurations
• H 1s1 He 1s2
• Li 1s2, 2s1 Ne 1s2, 2s2, 2p6
• Na 1s2, 2s2, 2p6, 3s1 Ar 1s2, 2s2, 2p6,
  3s2, 3p6
• K 1s2, 2s2, 2p6, 3s2, 3p6, 4s1
• K Ar 4s1
• Kr 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6
• Kr Ar 4s2, 3d10, 4p6

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Atomic Structure and the Periodic Table contd

• Electronic Configurations of Transition Elements
• Fe 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d6
• Br 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p5
• Pb 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2,
  4d10,
• 5p6, 6s2, 4f14, 5d10, 6p2

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Atomic Structure and the Periodic Table contd

• Which of the following electron configurations is
  correct for
• A)  
• B)  
• C)  
• D)  
• E)  

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Atomic Structure and the Periodic Table contd

• Give the symbol of the element that has
• A. Ar4s2 3d6
• B. Four 3p electrons
• C. Two electrons in the 4d sublevel
• D. The element that has the electron
  configuration
• 1s2 2s2 2p6 3s2 3p6 4s2 3d2
• 1s2 2s2 2p6 3s2 3p6 3d4

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Atomic Structure and the Periodic Table contd

• Drawing Orbital Diagrams
• First, write out the electron configuration
• Start drawing the orbital diagram
• --1 orbital (blanks) for every s subshell
• --3 orbitals(blanks) for every p subshell
• --5 orbitals (blanks) for every d subshell
• Blanks are circles or squares

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Atomic Structure and the Periodic Table contd

• Orbital Diagrams
• Li
• Na
• Na1

??
?
1s2 2s1 2p 3s
3p
??
??
??
??
??
?
1s2 2s2 2p6 3s1
3p
??
??
??
??
??
1s2 2s2 2p6 3s
3p
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Atomic Structure and the Periodic Table contd

• Orbital Diagrams
• N
• O
• O2-

??
??
?
?
?
1s2 2s2 2p3 3s
3p
??
??
??
?
?
1s2 2s2 2p4 3s
3p
??
??
??
??
??
1s2 2s2 2p6 3s
3p
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Atomic Structure and the Periodic Table contd

• CC 3.3
• The different colors of fireworks result when
  heat excites the electrons of different kinds of
  metal atoms.

William S. Helsel/Getty Images
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Atomic Structure and the Periodic Table contd

• Electron Configuration and the Periodic Law
• We said that elements in the same group have
  similar chemical reactivities
• Electrons are the subatomic particles involved in
  chemical reactions
• Which electrons are most likely to be involved in
  chemical reactions?
• A) those nearest to the nucleus
• B) those farthest from the nucleus
• C) all are equally likely to be involved

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Atomic Structure and the Periodic Table contd

• What differentiates one family from another?
• Lets look at the electron configurations
  (valance electron configurations) of the alkali
  metals to find out.
• Li
• Na
• K
• Rb
• Cs
• Fr

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Atomic Structure and the Periodic Table contd

• Elements with similar properties have the same
  type of distinguishing electron! (_________
  electrons)
• The last electron added to the electron
  configuration for an element when electron
  subshells are filled in order of increasing
  energy
• It is also the one that causes an elements
  electron configuration to differ from that of the
  element immediately preceding it in the periodic
  table

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