Download What is an atom?

Atomic
Structure
1
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Overview of topic
Electronic
Structure
and the
Periodic
Table
Electronic
Arrangement
Ions
Structure
of Atoms
Atomic
Structure
Isotopes
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Today’s Menu
• What is an atom
• Structure of an atom
• Relative charges and approximate
relative masses of proton,
neutron and an electron
• Symbol of an atom
• Proton number, nucleon number
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What is an atom?
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What is an atom
• All matters are made up of
atoms
• Atoms are extremely small in
size
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What is an atom
• Picture of lithium
atoms in the compound
lithium cobalt oxide
• Taken with a
transmission electron
microscope, which can
magnify objects up to
500,0000 times
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What is an atom
• An atom consists of 3 subatomic
particles:
1)Protons
2)Neutrons
3)Electrons
• Atom is a particle which is
electrically neutral
• No. of protons = No. of electrons
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Structure of an
Atom
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Structure of an Atom
•
•
•
+
•
•
•
Shells
Electrons
Nucleus
Protons
and
Neutrons
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Structure of an Atom
Shells
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Structure of an Atom
•
•
•
•
Shells
Electrons
•
•
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Structure of an Atom
•
•
•
+
•
•
•
Shells
Electrons
Nucleus
Protons
and
Neutrons
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Structure of an Atom
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Relative charges and
approximate relative
masses
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Particle
Charge
Relative Mass
Remarks
Proton
(p)
+1
1
• Mass is the same as that
of a hydrogen atom
• Found in the nucleus of
the atom
Neutron
(n)
0
1
• Mass is the same as that
of a hydrogen atom
• Found in the nucleus of
the atom
Electron
(e-)
-1
1/1840
(negligible)
• One hydrogen atom
weighs as much as 1836
electrons
• Found around the
nucleus.
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Symbol of an
atom
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Symbol of an atom
Nucleon Number
Chemical
Symbol
Proton Number
E.g.
24
12
16
40
Mg, 8 O, 18 Ar
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Proton number,
nucleon number
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Proton number
• Proton number (atomic number)
The number of protons in an
atom
• For an atom,
no. of protons = no. electrons
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Nucleon number
• Nucleon number (mass number)
= no. of protons + no. neutrons
• No. of Neutrons
= Nucleon number – Proton number
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Example
Given
64
29
,
Cu
(a)
What is the proton number?
Ans:
29
(b)
What is the number of electrons in Cu
atom?
Ans:
29
(c)
What is the nucleon number?
Ans:
64
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Summary
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Summary
• Structure of an atom
Electrons
+
Nucleus
Protons
and
Neutrons
• Relative charges and
approximate relative masses of
protons, neutrons and electrons
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Summary
• Symbol of an atom
Nucleon Number
Chemical
Symbol
Proton Number
• Proton number, nucleon number
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Any
Questions
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