1.Atomic Structure

7/29/2019 1.Atomic Structure

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Atomic Structure

Guna Selvaduray

MatE 115


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2

G.

Selvaduray,

SJS

U,

Fall2006

Describe the structure of an atom, including

number of neutrons, protons, electrons,atomic weight and atomic number.

Explain similarities and differences among

Describe ionization potential Identify 1st, 2nd and 3rd ionization potentials

and the relationship to stoichiometry and

nonstoichiometry in compounds. Describe electron affinity

Describe electronegativity


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G.

Selvaduray,

SJS

U,

Fall2006

Structure of the Atom

Atomic Weight

Atomic Number

Number of Protons

Number of Neutrons Number of Electrons


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G.

Selvaduray,

SJS

U,

Fall2006

Quantum Numbers

n: Principal quantum number n= 1, 2, 3,

Corresponding electronic shells: K, L, M, Major determining factor for energy

l: Angular momentum l= 0, 1, 2, , n-1 Corresponds to: s, p, d, f, electrons s electrons (l= 0) have zero angular momentum

They have spherical orbitals p, d, f, .. electrons have directionality to their orbitals

ml: magnetic quantum number -l< ml< +l Specifies orientation of angular momentum in space

ms: spin


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G.

Selvaduray,

SJS

U,

Fall2006

Spin

ms: angular momentum of electron due to

spinning on its own axis ms = + or -

Paulis Exclusion Principle:

No two electrons in a given atom can havethe same set of quantum numbers


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G.

Selvaduray,

SJS

U,

Fall2006

Quantum State

Specified by a unique combination of:

n, m, ml, ms

Orbitals withnucleus as

center

Spin wrtelectronsaxis


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G.

Selvaduray,

SJS

U,

Fall2006

Electronic Structure

SnO, SnO21s22s22p63s23p23d104s24p64d105s25p2Sn

Cu2O, CuO1s2

2s2

2p6

3s2

3p2

3d10

4s1

Cu

FeO, Fe2O31s22s22p63s23p23d64s2Fe

SiO41s22s22p63s23p2Si

Al2O31s22s22p63s23p1Al

MgO1s22s22p63s2Mg

NaO1s22s22p63s1Na

CompoundsElectronic StructureElement


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G.

Selvaduray,

SJS

U,

Fall2006

Atoms, Ions and Isotopes.

Atoms

Features Examples

Ions Features

Examples

Isotopes Features

Examples


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G.

Selvaduray,

SJS

U,

Fall2006

Isotope nomenclature

Types of radiation : helium particles

: electrons

: electromagnetic radiation

U234

92 He

4

2


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G.

Selvaduray,

SJS

U,

Fall2006

Production of Isotopes

Isotopic separation

Target isotope bombarded with (charged)particles

Neutron capture with decay

nIrdOs1

0

192

77

2

1

192

76 2++

++ PdnPd

103

46

1

0

102

46


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G.

Selvaduray,

SJS

U,

Fall2006

Ionization Potential

Energy required to remove an electron

from the atom 1st, 2nd, 3rd, .. Ionization Potential

Relationship of Ionization Potential to: Stoichiometric Compounds, and

Nonstoichiometric Compounds

Units: eV;Sources: W.J. Moore, Physical Chemistry, and L. Pauling,The Nature of the Chemical Bond

0.750.28Cu5.650.670.35Be

2.950.550.28Mg

1.880.440.23Ca

2.621.750.19Na

I3I2I1Element


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Selvaduray,

SJS

U,

Fall2006

Ionization Potential = Ionization Energy

Electron Affinity: Energy given up when an initially free

electron is added to the outer shell of an

atom


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G.

Selvaduray,

SJS

U,

Fall2006

Not to be Confused with

Electropositive elements: Elements which, in their elemental state, nearly

always donate one or more electrons per atom whenthey react chemically to yield stable compounds.

They are electron donors, and their atoms tend to

become positive ions Electronegative elements:

The uncharged atoms of these elements tend to

become negative ions if possible, or at least theytend to attract electrons.

They are electron-acceptors


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G.

Selvaduray,

SJS

U,

Fall2006

Electronegativity

Tendency of an atom to gain an electron


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G.

Selvaduray,

SJS

U,

Fall2006

Table of Electronegativities

Source: L. Pauling, Nature of the Chemical Bond


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Selvaduray,

SJSU,

Fall2006

Electronegativity & Atomic

Bonding

Fraction Covalent Bonding =

Fraction Ionic Bonding =

)25.0exp(

2E

Documents

1.Atomic Structure