atomic structure isotopes

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

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 PUDDING

MODEL

Niels Bohr(1885-1962)

Bohr’s Atom

electrons in orbits

nucleus

http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/atom.swf

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





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





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





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

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


2. Uses of Isotopes

Pair Work

Uses of Radioactive Isotopes

• Food irradiation• Archaeological dating (carbon-dating)• Smoke detectors• Radioactive tracers

Summary


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.

SAME P DIFFERENT N

Quiz

• http://chemistry.about.com/library/weekly/blionquiz.htm

http://chemistry.about.com/library/weekly/blionquiz.htm

http://chemistry.about.com/library/weekly/blionquiz.htm

atomic structure isotopes

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