Lesson Objectives
1. Recap Atomic Structure
2. Isotopes
Lesson Objectives
1. Recap Atomic Structure
2. Isotopes
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
The Atomic Structure
WHAT IS AN ATOM?
Atoms are the smallest particle of an element.
WHAT IS AN ELEMENT?
pure substance that cannot be
•An element is a ____
spilt
_____up
into 2 or more simpler substances by
chemical processes.
The Story
of
Atoms
Atoms have positive
charges concentrated in
their small nucleus!
There are
neutrons!
Democritus
460 BC
Joseph John
Thompson
(1856-1940)
PLUM
PUDDING
MODEL
1898
Ernest
Rutherford
(1871 -1937)
Sir James
Chadwick
(1891 -1974)
Niels Bohr
(1885-1962)
Bohr’s Atom
electrons in orbits
nucleus
http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/atom.swf
Structure of Atom
A positively
charged nucleus,
densely
concentrated in
the centre.
The nucleus
contains protons
and neutrons,
which are tightly
packed.
An atom consists
mostly of empty
space.
Negatively
charged
electrons move 10
around the
nucleus in fixed
orbits or paths.
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton,
neutron and electron
C. Chemical symbols
D. Electronic configuration
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton,
neutron and electron
C. Chemical symbols
D. Electronic configuration
Relative Charges & Relative Masses Of
Protons, Neutrons & Electrons
Sub-atomic
particles
Symbol
Relative
mass
Relative
charge
*Proton
p
1
+1
*Neutron
n
1
0
*Electron
e
1/1840
-1
•When No. of proton = no. of electrons in an atom
•It is electrically neutral
•It has no net charge.
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
Interpreting Chemical Symbol
Mass=P+N
mass number
(nucleon number)
mass number is the total number
of protons and neutrons in an
atom.
Number of neutrons in the
oxygen atom is: 16 – 8 = 8.
proton number
(atomic number)
P=E
No. of
protons= no.
of electrons
16
O
chemical symbol
8
atomic number (proton number) is the number of
protons in an atom.
Each oxygen atom has 8 protons.
As the number of electrons is equal to the number of
protons in an atom, each oxygen atom contains 8
electrons.
16
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
Recap on Atomic Structure
A. Structure of atom
B. Relative masses and charges of proton, neutron
and electron
C. Chemical symbols
D. Electronic configuration
The Electronic Configuration of Atoms
16
O
8
Atomic
number
(Proton)
Mass number
(Nucleon)
O
The Electronic Configuration of Atoms
Mg
Summary for Atomic Structure (I)
• The structure of an atom
• The relative charges & relative masses of
proton, neutron & electron
• Defined mass number & atomic number
• Learnt how to interpret chemical symbols
• The electronic configuration of atoms
Lesson Objectives
1. Recap Atomic Structure
2. Isotopes
Today…
Isotopes
Isotopes
1. Definition of Isotopes
2. Uses of Isotopes
Isotopes
1. Definition of Isotopes
2. Uses of Isotopes
Activity
• Find your fellow group members! (1min)
Definition of Isotopes
Isotopes are atoms of the same
element which contains the same
number of protons but different
number of neutrons.
Isotopes
mass
number
proton
number
16
17
18
8
8
8
O O O
Oxygen-16
n = 8
Oxygen-17
n = 17 – 8
= 9
Oxygen-18
n = 18 – 8
= 10
Isotopes
Isotopes have the same chemical
properties but slightly different
physical properties
Q. DO ALL ISOTOPES OF THE SAME
ELEMENT HAVE THE SAME MASS?
Isotopes
1. Definition of Isotopes
2. Uses of Isotopes
Pair Work
Uses of Radioactive Isotopes
•
•
•
•
Food irradiation
Archaeological dating (carbon-dating)
Smoke detectors
Radioactive tracers
Summary
Recap on Atomic Structure
1. Definition of Isotopes
2. Uses of Isotopes
Definition of Isotopes
Isotopes are atoms of the same
element which contains the same
number of protons but different
number of neutrons.
Quiz
• http://chemistry.about.com/library/weekly/bli
onquiz.htm