Structure of an atom
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STRUCTURE OF AN ATOM. STRUCTURE OF AN ATOM. ELECTRON - the NEGATIVE particles surrounding the nucleus of an atom. discovered by JOSEPH JOHN THOMPSON. STRUCTURE OF AN ATOM. PROTON – positively charged particle in the nucleus of the atom Discovered by Eugene Goldstein. STRUCTURE OF AN ATOM.

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STRUCTURE OF AN ATOM

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Structure of an atom

STRUCTURE OF AN ATOM


Structure of an atom1

STRUCTURE OF AN ATOM

  • ELECTRON - the NEGATIVE particles surrounding the nucleus of an atom.

  • discovered by JOSEPH JOHN THOMPSON


Structure of an atom2

STRUCTURE OF AN ATOM

  • PROTON – positively charged particle in the nucleus of the atom

  • Discovered by Eugene Goldstein


Structure of an atom3

STRUCTURE OF AN ATOM

NEUTRON – a neutral subatomic particle present in the nucleus of an atom

Discovered by James Chadwick in 1932


Electron cloud model

Electron Cloud Model


Dalton s atomic theory has the following postulates

DALTON’S ATOMIC THEORY has the following postulates.

1) Matter is made up of extremely small indestructible particles called atoms.

2) All atoms of a given element are alike

John Dalton – English chemist that proposed the first atomic theory in 1803


Dalton s atomic theory has the following postulates1

DALTON’S ATOMIC THEORY has the following postulates.

3) Atoms enter into combination with other atoms to form compounds, but remain unchanged during ordinary chemical reactions.

4) Atoms can combine in simple numerical ratios such as 1:1, 1:2, 2:3 and so on.

Dalton’s Atomic Model


Dalton s atomic theory gives sufficient explanation to the three laws of chemical combination

Dalton’s atomic theory gives sufficient explanation to the Three Laws of Chemical Combination.

Law of Conservation

of Mass

There is no detectable change in the masses of substances before and after the course of an ordinary chemical reaction. Mass is conserved.

Dalton’s 3rd postulate


Laws of chemical combination explains mass relationships in chemical reactions

Laws of Chemical Combination explains mass relationships in chemical reactions.

Law of Definite

Proportions or composition.

A pure compound always contains the same elements combined in the same proportions or percentage by mass.

% C = Mass of C / mass of CO2 x 100

% O = Mass of O/ mass of CO2 x 100

Dalton’s 2nd and 3rd postulate


Laws of chemical combination explains mass relationships in chemical reactions1

Laws of Chemical Combination explains mass relationships in chemical reactions.

Law of Multiple

Proportions

When two elements combine to form more than one compound, the masses of one element which combine with a fixed mass of the other element are in a ratio of SMALL whole numbers

  • H2O (water)

  • H2O2 (Hydrogen peroxide)

  • Mass O = 16 g

  • Mass of H = 1 g

  • Since the

  • Atom of oxygen always has the same mass

  • Ratio = 2:1


Sample atomic structure

Sample Atomic Structure

Hydrogen: a proton surrounded by an electron cloud

A Hydrogen Atom


Structure of an atom

35

Cl

17


Structure of an atom

Hydrogen Atomic Mass = 1 Atomic Number = 1

Deuterium  Atomic Mass = 2  Atomic Number = 1

Two isotopes of hydrogen


References

References

  • http://dbhs.wvusd.k12.ca.us/AtomicStructure/AtomicStructure.html

  • http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm


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