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Structure of the Atom

 
2.3  Structure of Atom
 
Proton Number and Nucleon Number
  • Proton number: the number of protons in the nucleus of an atom. 
    • \(\text{Proton number} = \text{Number of proton }\)
  • In a neutral atom, the number of electrons and protons are the same.
  • Nucleon number: the total number of protons and neutrons. 
    • \(\text{Nucleon number} = \text{Number of protons}+ \text{Number of neutrons}\)
  • The nucleon number of an atom is about the same as the mass of the atom. 
 
Number of Subatomic Particles of Chlorine Atom and Chloride Ion
Type of Particle Chlorine Atom, Cl Chloride Ion, Cl ¯
Number of proton 17 17
Number of neutron 18 18
Number of electron 17 18
 
Standard Representation of an Atom
This image is a diagram explaining the notation of a chemical element. It features three red boxes on a light blue background. The leftmost box contains the text ‘Nucleon number’ at the top and ‘Number of protons’ at the bottom. The middle box has a large letter ‘Z’ in white, with a smaller ‘x’ above it and a smaller ‘y’ below it. The rightmost box contains the text ‘Symbol of element.’
 
Electron Arrangement of an Atom
  • Neils Bohr suggested there is an energy level for each electron that occupy the orbits.
  • The orbits with definite energy levels are known as the shell.
  • The total number of electron that can be filled by each petal is as below:

THE MAXIMUM NUMBER OF ELECTRONS CAN BE FILLED IN EACH SHELL. FIRST SHELL Can hold up to two electrons, SECOND SHELL Can hold up to eight electrons and THIRD SHELL Can hold up to eight electrons. Pandai.

  • For a simpler representation of the electron arrangement of the elements, the number of electrons in each shell is written and separated by a dot. 
  • Valence electrons are the electron in the outermost shell
  • The valence electron has a great significance in determining the chemical properties of the elements. 
  • Element with the same number of valence electrons has the same chemical properties
  • Below shows examples of the electron arrangement of the first twenty elements in the Periodic Table of Elements.
 

Element

Electron Arrangement

Number of Valence Electrons

Hydrogen

 1

1

Helium

 2 2
Litium

2.1

1

Beryllium

 2.2 2

Boron

2.3

 3
Carbon 2.4

4
Nitrogen

2.5

 5
Oxygen 2.6

6

Fluorine

 2.7 7

Neon

 2.8 8

Sodium

 2.8.1 1

Magnesium

 2.8.2 2

Aluminium

 2.8.3 3

Silicone

 2.8.4 4

Phosphorus

 2.8.5 5

Sulfur

 2.8.6 6

Chlorine

 2.8.7 7

Argon

 2.8.8 8
Potassium

2.8.8.1

1

Calcium

 2.8.8.2 2
 
Electron Arrangement of Carbon
This image illustrates the atomic structure of an element. It shows a nucleus labeled ‘C’ at the center, surrounded by two electron shells. The first electron shell contains two electrons, while the second electron shell contains four electrons. Labels indicate the ‘First electron shell,’ ‘Second electron shell,’ and ‘Electron’ for individual electrons. The background resembles lined notebook paper.
 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.

Structure of the Atom

 
2.3  Structure of Atom
 
Proton Number and Nucleon Number
  • Proton number: the number of protons in the nucleus of an atom. 
    • \(\text{Proton number} = \text{Number of proton }\)
  • In a neutral atom, the number of electrons and protons are the same.
  • Nucleon number: the total number of protons and neutrons. 
    • \(\text{Nucleon number} = \text{Number of protons}+ \text{Number of neutrons}\)
  • The nucleon number of an atom is about the same as the mass of the atom. 
 
Number of Subatomic Particles of Chlorine Atom and Chloride Ion
Type of Particle Chlorine Atom, Cl Chloride Ion, Cl ¯
Number of proton 17 17
Number of neutron 18 18
Number of electron 17 18
 
Standard Representation of an Atom
This image is a diagram explaining the notation of a chemical element. It features three red boxes on a light blue background. The leftmost box contains the text ‘Nucleon number’ at the top and ‘Number of protons’ at the bottom. The middle box has a large letter ‘Z’ in white, with a smaller ‘x’ above it and a smaller ‘y’ below it. The rightmost box contains the text ‘Symbol of element.’
 
Electron Arrangement of an Atom
  • Neils Bohr suggested there is an energy level for each electron that occupy the orbits.
  • The orbits with definite energy levels are known as the shell.
  • The total number of electron that can be filled by each petal is as below:

THE MAXIMUM NUMBER OF ELECTRONS CAN BE FILLED IN EACH SHELL. FIRST SHELL Can hold up to two electrons, SECOND SHELL Can hold up to eight electrons and THIRD SHELL Can hold up to eight electrons. Pandai.

  • For a simpler representation of the electron arrangement of the elements, the number of electrons in each shell is written and separated by a dot. 
  • Valence electrons are the electron in the outermost shell
  • The valence electron has a great significance in determining the chemical properties of the elements. 
  • Element with the same number of valence electrons has the same chemical properties
  • Below shows examples of the electron arrangement of the first twenty elements in the Periodic Table of Elements.
 

Element

Electron Arrangement

Number of Valence Electrons

Hydrogen

 1

1

Helium

 2 2
Litium

2.1

1

Beryllium

 2.2 2

Boron

2.3

 3
Carbon 2.4

4
Nitrogen

2.5

 5
Oxygen 2.6

6

Fluorine

 2.7 7

Neon

 2.8 8

Sodium

 2.8.1 1

Magnesium

 2.8.2 2

Aluminium

 2.8.3 3

Silicone

 2.8.4 4

Phosphorus

 2.8.5 5

Sulfur

 2.8.6 6

Chlorine

 2.8.7 7

Argon

 2.8.8 8
Potassium

2.8.8.1

1

Calcium

 2.8.8.2 2
 
Electron Arrangement of Carbon
This image illustrates the atomic structure of an element. It shows a nucleus labeled ‘C’ at the center, surrounded by two electron shells. The first electron shell contains two electrons, while the second electron shell contains four electrons. Labels indicate the ‘First electron shell,’ ‘Second electron shell,’ and ‘Electron’ for individual electrons. The background resembles lined notebook paper.
 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.
Chapter : Matter and Atomic Structure
Topic : Structure of the Atom
Form 4 Chemistry
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