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1. Recap Atomic Structure 2. Isotopes Lesson Objectives NEW
1. Recap Atomic Structure
2. Isotopes
Lesson Objectives
NEW
1. Recap Atomic Structure
2. Isotopes
Lesson Objectives
NEW
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
The Atomic Structure
WHAT IS AN ATOM?Atoms are the smallest particle of an element.
WHAT IS AN ELEMENT?•An element is a ____ substance that cannot be _____up into 2 or more simpler substances by chemical processes.
purespilt
The Story of Atoms
Ernest Rutherford (1871 -1937)
Democritus 460 BC
Sir James Chadwick (1891 -1974)
1898
Joseph John Thompson (1856-1940)
Atoms have positive charges concentrated in their small nucleus!
There are neutrons!
ATOMA
PLUM PUDDINGMODEL
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
10
An atom consists mostly of empty space.
Negatively charged electrons move around the nucleus in fixed orbits or paths.
A positively charged nucleus, densely concentrated in the centre. The nucleus contains protons and neutrons, which are tightly packed.
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
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.
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
16
O16
8
chemical symbol
mass number(nucleon number)
proton number(atomic number)
P=ENo. of protons= no. of electrons
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.
Mass=P+N
mass number is the total number of protons and neutrons in an atom.Number of neutrons in the oxygen atom is: 16 – 8 = 8.
Interpreting Chemical Symbol
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
C. Chemical symbols
B. Relative masses and charges of proton, neutron and electron
A. Structure of atom
D. Electronic configuration
Recap on Atomic Structure
The Electronic Configuration of Atoms
O O16
8
Mass number(Nucleon)
Atomicnumber(Proton)
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
1. Recap Atomic Structure
2. Isotopes
Lesson Objectives
NEW
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.
SAME P DIFFERENT N
Isotopes
O16
8
mass number
proton number
Oxygen-16 Oxygen-17 Oxygen-18
O O17
8
18
8
n = 8 n = 17 – 8 = 9
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
1. Definition of Isotopes
2. Uses of Isotopes
Recap on Atomic Structure
Definition of Isotopes
Isotopes are atoms of the same element which contains the same number of protons but different
number of neutrons.
SAME P DIFFERENT N
Quiz
• http://chemistry.about.com/library/weekly/blionquiz.htm
