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8/14/2019 Int Chem Chap 2
http://slidepdf.com/reader/full/int-chem-chap-2 2/25
Matter
Anything that occupies space and has mass
Matter
Element Compound
Atom Molecule Molecule Ion
8/14/2019 Int Chem Chap 2
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Particulate nature of matter
Tiny and discrete
Diffusion proves that matter is made
up of tiny particles.
8/14/2019 Int Chem Chap 2
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Kinetic theory of matter
Matter consists of tiny, discrete particles
that are constantly moving.
The particles move in a random motion
and collide with one another .
8/14/2019 Int Chem Chap 2
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Heating graphCompletely melted
Completely vaporised
Even heating
Melting point > 100°C?
8/14/2019 Int Chem Chap 2
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Cooling Graph
Even cooling
Energy lost = heat energy released
8/14/2019 Int Chem Chap 2
http://slidepdf.com/reader/full/int-chem-chap-2 10/25
2.2 Atomic structure
8/14/2019 Int Chem Chap 2
http://slidepdf.com/reader/full/int-chem-chap-2 11/25
2.2 Atomic structure
8/14/2019 Int Chem Chap 2
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Atomic Structure
Proton number
= number of protons
Nucleon number = no. of neutrons + no.
of proton
8/14/2019 Int Chem Chap 2
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2.3 Isotopes
The Isotopes of an element are the atoms
of that element which contain the same
number of protons but a different number
of neutrons.
8/14/2019 Int Chem Chap 2
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The Uses of Isotopes
Medical (a) Cobalt-60 are used in radiotherapy
(b) Iodine-131 can be injected into the thyroid gland of
patient with hyperthyroidism (over-active thyroid gland) todestroy the hyperactive thyroid cells.
(c) Sodium-24 is injected into the body to identify thelocation of a blood clot.
(d) Carbon-14 are used in determine the age of fossil.
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
1 The electron configuration (electron
arrangement) of an atom is the
arrangement of electrons in shells (orbits)
around that atom's nucleus.
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
2 The electrons in an atom are arranged
in shells around the nucleus. The
maximum number of electrons which can
fill a particular shell is as follows:
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
3 The electrons in the last shell of an
atom are known as valence electrons.
They determine the chemical properties of
the element.
8/14/2019 Int Chem Chap 2
http://slidepdf.com/reader/full/int-chem-chap-2 20/25
2.4 The Electronic Structure of an
Atom
4. Sulphur has 16 electrons:
The electronic configuration or electron
arrangement is then written as 2.8.6.
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
5 All elements having the same valence
electrons will show the same chemical
properties, for example, chlorine and
bromine, have 7 valence electrons, willexhibit similar chemical properties.
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
6 Helium has a complete shell of 2 valence
electrons or duplet condition. Similarly, neon
and argon also have complete shells. They have
8 valence electrons or the octet condition.These elements are monoatomic and are very
stable gases.
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
7 The electron arrangement of an
element, for example;Na is constructed by
drawing 3 circles around the nucleus to
represent each shell, as its electronconfiguration is 2.8.1. Thus we have
8/14/2019 Int Chem Chap 2
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2.4 The Electronic Structure of an
Atom
8 Table 2.5 shows the electron arrangement of
the first 20 elements in the Periodic Table.