1.14-1.17 IGCSE Chemistry 2018

1 Principles of chemistry 

2 Inorganic chemistry 

3 Physical chemistry 

4 Organic chemistry 

1 Principles of chemistry 

(c) Atomic structure 

Students should: 

1.14 know what is meant by the terms atom and molecule 1.15 know the structure of an atom in terms of the positions, relative masses and relative charges of sub-atomic particles 1.16 know what is meant by the terms atomic number, mass number, isotopes and relative atomic mass (Ar) 1.17 be able to calculate the relative atomic mass of an element (Ar) from isotopic abundances

Notes:

• a) States of matter
• b) Elements compounds and mixtures
• c) Atomic structure

• Atomic Structure 1 MS
• Atomic Structure 1 QP

1.14: Know What is Meant by the Terms Atom and Molecule

DEFINITIONS:

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TERM	DEFINITION
ATOM	The Smallest Particle of an Element that Consists of Electrons Surrounding a Nucleus that Contains Protons and Neutrons
MOLECULE	The Smallest Particle of a Substance that is Formed when Atoms Join Together by Chemical Bonds

1.15: Know the Structure of an Atom in Terms of the Positions, Relative Masses and Relative Charges of Sub-Atomic Particles

Atoms are Made Up of Sub - Atomic Particles called Protons, Neutrons and Electrons

PARTICLE	RELATIVE CHARGE	RELATIVE MASS
PROTON	+1	1
NEUTRON	0	1
ELECTRON	-1	1/1836

1.16: Know What is Meant by the Terms Atomic Number, Mass Number, Isotopes and Relative Atomic Mass (Ar)

DEFINITIONS:

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TERM	DEFINITION
ATOMIC NUMBER	The Number of Protons in the Nucleus of an Atom
MASS NUMBER	The Sum of the Number of Protons and Neutrons in the Nucleus of an Atom
ISOTOPES	Atoms of the Same Element that Contains the Same Atomic Number but Different Mass Number
RELATIVE ATOMIC MASS (Ar)	Measure of the Mass of One Atom of the Element

1.17: Be Able to Calculate the Relative Atomic Mass of an Element (Ar) from Isotopic Abundances

ISOTOPES: Atoms of the Same Element that Contains the Same Atomic Number but Different Mass Number

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EQUATION:

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Ar = % of Isotope 1 x Mass of Isotope 1 + % of Isotope 2 x Mass of Isotope 2

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Example:

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The Table Shows Information about the Isotopes in a sample of Rubidium ISOTOPE NUMBER OF PROTONS NUMBER OF NEUTRONS PERCENTAGE OF ISOTOPE IN SAMPLE 1 37 48 72% 2 37 50 28%       Use Information from the Table to Calculate the Relative Atomic Mass of        this Sample of Rubidium. Give your Answer to One Decimal Place      72%   x   85     +     28%   x   87   =   85.6        Relative Atomic Mass = 85.6