1.1.5
Model of the Atom
The Model of the Atom
The Model of the Atom
Our understanding of atoms has improved over time. The models that we have used to understand atoms have also changed.
Thomson's plum pudding model
Thomson's plum pudding model
- In 1897, an English physicist called J. J. Thomson discovered electrons.
- Thomson modelled the atom as a 'plum pudding' - a ball of positive charge (dough), with negatively charged electrons (currants in pudding) mixed in with the 'dough'.
Rutherford's nuclear model
Rutherford's nuclear model
- In 1909, Ernest Rutherford discovered that alpha particles could bounce back off atoms.
- Rutherford concluded that an atom's mass is concentrated in the atom's centre. This was called the "nucleus" and it contained positively charged particles called protons.
The modern model
The modern model
- Niels Bohr discovered that electrons orbit (fly around) the nucleus at fixed distances.
- In 1932, James Chadwick discovered that some particles in the nucleus have no charge at all. He called them neutrons.
The Charges of Sub-Atomic Particles
The Charges of Sub-Atomic Particles
The 3 different sub-atomic particles (protons, neutrons and electrons) have different relative charges. In an atom, these charges all cancel each other out., meaning that atoms have zero overall charge (are neutral).
Protons (+1)
Protons (+1)
- Protons have a relative charge of +1.
- Protons are found in the nucleus.
- An element’s atomic number is the number of protons it has.
- All atoms of the same element will have an identical number of protons.
Electrons (-1)
Electrons (-1)
- Electrons have a relative charge of -1.
- Electrons are found in fixed orbits around the nucleus.
- In any atom, the total number of negative electrons equals the number of positive protons, meaning atoms have no overall electric charge.
Neutrons (0)
Neutrons (0)
- Neutrons have a relative charge of 0 - they are neutral.
- Like protons, they are found in the nucleus.
1Atomic Structure
1.1Atoms & Elements
1.1.1Elements & Compounds
1.1.2Chemical Reactions & Equations
1.1.3Mixtures
1.1.4Separating Mixtures
1.1.5Model of the Atom
1.1.6Atom Size & Number
1.1.7Atomic Number - Calculations
1.1.8Isotopes
1.1.9Isotopes HyperLearning
1.1.10Isotopes - Calculations
1.1.11Relative Atomic Mass
1.1.12Electron Structure
1.1.13Periodic Table
1.1.14Metals & Non-Metals
1.1.15Noble Gases
1.1.16Halogens
1.1.17Alkali Metals
1.1.18Transition Metals
1.1.19End of Topic Test - Atomic Structure
1.1.20Grade 9 - Atoms & Elements
1.1.21Exam-Style Questions - Atomic Structure
1.1.22Application Questions - Atomic Structure
2Chemical Bonding
2.1Chemical Bonds
2.2States of Matter
2.3Chemical Properties
2.3.1Chemical Properties of Ionic Compounds
2.3.2Chemical Properties of Small Molecules
2.3.3Molecular Forces & Polymers
2.3.4Metals & Giant Covalent Structures
2.3.5Alloys & Conductors
2.3.6Carbon Structures - Diamond & Graphite
2.3.7Carbon Structures - Graphene & Fullerenes
2.3.8Carbon Structures - Summary
2.3.9Nanoparticles
2.3.10Nanotechnology
2.3.11Surface Area to Volume Ratio & Nanotechnology Uses
2.3.12End of Topic Test - Chemical Bonding
2.3.13Grade 9 - Bonding & Structure
2.3.14Exam-Style Questions - Allotropes of Carbon
3Quantitative Chemistry
3.1Chemical Measurements
3.1.1Conservation of Mass
3.1.2Relative Formula Mass
3.1.3Relative Formula Mass - Calculations
3.1.4Measuring Mass
3.1.5Equations & Formula
3.1.6Moles 1
3.1.7Moles 2
3.1.8Moles 3
3.1.9Moles - Calculations
3.1.10Percentage Yield
3.1.11Percentage Yield - Calculations
3.1.12Moles & Yield
3.1.13Atom Economy
3.1.14Atom Economy - Calculations
3.1.15Concentrations & Amounts
3.1.16Amount of Substance in Relation to Volumes and Gas
3.1.17Concentrations & Amounts - Calculations
3.1.18Empirical Formula - Calculations
3.1.19End of Topic Test - Quant Chemistry
3.1.20Grade 9 - Quantitative Chemistry
3.1.21Exam-Style Questions - Moles
4Chemical Changes
4.1Acids, Alkalis & Redox Reactions
4.2Reactivity of Metals
4.3Reactions of Acids
5Energy Changes
5.1Exothermic & Endothermic Reactions
6The Rate & Extent of Chemical Change
6.1Rate of Reaction
7Organic Chemistry
7.1Carbon Compounds
7.2Alkenes & Alcohols
7.2.1Structure of Alkenes
7.2.2Reactions of Alkenes
7.2.3End of Topic Test - Alkanes & Alkenes
7.2.4Alcohols
7.2.5Reactions of Alcohols
7.2.6Carboxylic Acids
7.2.7Reactions of Carboxylic Acids
7.2.8Addition Polymers
7.2.9Condensation Polymers
7.2.10Naturally Occurring Polymers - Proteins
7.2.11Naturally Occurring Polymers - DNA & Sugars
7.2.12End of Topic Test - Alcohols, Acids & Polymers
7.2.13Grade 9 - Organic Chemistry
7.2.14Exam-Style Questions - Alcohols
8Chemical Analysis
8.1Purity, Formulations & Chromatography
8.2Identification of Common Gases
8.3Identifying Ions
8.3.1Flame Tests
8.3.2Required Practical: Flame Tests
8.3.3Metal Hydroxides
8.3.4Carbonates
8.3.5Halides, Sulfates
8.3.6Methodology for Chemical Analysis
8.3.7Flame Emission Spectroscopy
8.3.8End of Topic Test - Chemical Analysis
8.3.9Grade 9 - Chemical Analysis
8.3.10Exam-Style Questions - Identification of ions
9Chemistry of the Atmosphere
9.1The Earth's Atmosphere
9.1.1Proportions of Gases in the Atmosphere
9.1.2Oxygen & Carbon Dioxide in the Atmosphere
9.1.3Greenhouse Gases & Human Activities
9.1.4Greenhouse Gases & Human Activities
9.1.5Greenhouse Gases & Climate Change
9.1.6Carbon Footprints
9.1.7Common Atmospheric Pollutants & Their Properties
9.1.8End of Topic Test - The Earth
9.1.9Grade 9 - Chemistry of the Atmosphere
9.1.10Exam-Style Questions - Earth's Atmosphere
10Using Resources
10.1Using the Earth's Resources
10.2Life Cycle Assessments & Recycling
10.3Using Materials
10.4The Haber Process & NPK Fertilisers
Jump to other topics
1Atomic Structure
1.1Atoms & Elements
1.1.1Elements & Compounds
1.1.2Chemical Reactions & Equations
1.1.3Mixtures
1.1.4Separating Mixtures
1.1.5Model of the Atom
1.1.6Atom Size & Number
1.1.7Atomic Number - Calculations
1.1.8Isotopes
1.1.9Isotopes HyperLearning
1.1.10Isotopes - Calculations
1.1.11Relative Atomic Mass
1.1.12Electron Structure
1.1.13Periodic Table
1.1.14Metals & Non-Metals
1.1.15Noble Gases
1.1.16Halogens
1.1.17Alkali Metals
1.1.18Transition Metals
1.1.19End of Topic Test - Atomic Structure
1.1.20Grade 9 - Atoms & Elements
1.1.21Exam-Style Questions - Atomic Structure
1.1.22Application Questions - Atomic Structure
2Chemical Bonding
2.1Chemical Bonds
2.2States of Matter
2.3Chemical Properties
2.3.1Chemical Properties of Ionic Compounds
2.3.2Chemical Properties of Small Molecules
2.3.3Molecular Forces & Polymers
2.3.4Metals & Giant Covalent Structures
2.3.5Alloys & Conductors
2.3.6Carbon Structures - Diamond & Graphite
2.3.7Carbon Structures - Graphene & Fullerenes
2.3.8Carbon Structures - Summary
2.3.9Nanoparticles
2.3.10Nanotechnology
2.3.11Surface Area to Volume Ratio & Nanotechnology Uses
2.3.12End of Topic Test - Chemical Bonding
2.3.13Grade 9 - Bonding & Structure
2.3.14Exam-Style Questions - Allotropes of Carbon
3Quantitative Chemistry
3.1Chemical Measurements
3.1.1Conservation of Mass
3.1.2Relative Formula Mass
3.1.3Relative Formula Mass - Calculations
3.1.4Measuring Mass
3.1.5Equations & Formula
3.1.6Moles 1
3.1.7Moles 2
3.1.8Moles 3
3.1.9Moles - Calculations
3.1.10Percentage Yield
3.1.11Percentage Yield - Calculations
3.1.12Moles & Yield
3.1.13Atom Economy
3.1.14Atom Economy - Calculations
3.1.15Concentrations & Amounts
3.1.16Amount of Substance in Relation to Volumes and Gas
3.1.17Concentrations & Amounts - Calculations
3.1.18Empirical Formula - Calculations
3.1.19End of Topic Test - Quant Chemistry
3.1.20Grade 9 - Quantitative Chemistry
3.1.21Exam-Style Questions - Moles
4Chemical Changes
4.1Acids, Alkalis & Redox Reactions
4.2Reactivity of Metals
4.3Reactions of Acids
5Energy Changes
5.1Exothermic & Endothermic Reactions
6The Rate & Extent of Chemical Change
6.1Rate of Reaction
7Organic Chemistry
7.1Carbon Compounds
7.2Alkenes & Alcohols
7.2.1Structure of Alkenes
7.2.2Reactions of Alkenes
7.2.3End of Topic Test - Alkanes & Alkenes
7.2.4Alcohols
7.2.5Reactions of Alcohols
7.2.6Carboxylic Acids
7.2.7Reactions of Carboxylic Acids
7.2.8Addition Polymers
7.2.9Condensation Polymers
7.2.10Naturally Occurring Polymers - Proteins
7.2.11Naturally Occurring Polymers - DNA & Sugars
7.2.12End of Topic Test - Alcohols, Acids & Polymers
7.2.13Grade 9 - Organic Chemistry
7.2.14Exam-Style Questions - Alcohols
8Chemical Analysis
8.1Purity, Formulations & Chromatography
8.2Identification of Common Gases
8.3Identifying Ions
8.3.1Flame Tests
8.3.2Required Practical: Flame Tests
8.3.3Metal Hydroxides
8.3.4Carbonates
8.3.5Halides, Sulfates
8.3.6Methodology for Chemical Analysis
8.3.7Flame Emission Spectroscopy
8.3.8End of Topic Test - Chemical Analysis
8.3.9Grade 9 - Chemical Analysis
8.3.10Exam-Style Questions - Identification of ions
9Chemistry of the Atmosphere
9.1The Earth's Atmosphere
9.1.1Proportions of Gases in the Atmosphere
9.1.2Oxygen & Carbon Dioxide in the Atmosphere
9.1.3Greenhouse Gases & Human Activities
9.1.4Greenhouse Gases & Human Activities
9.1.5Greenhouse Gases & Climate Change
9.1.6Carbon Footprints
9.1.7Common Atmospheric Pollutants & Their Properties
9.1.8End of Topic Test - The Earth
9.1.9Grade 9 - Chemistry of the Atmosphere
9.1.10Exam-Style Questions - Earth's Atmosphere
10Using Resources
10.1Using the Earth's Resources
10.2Life Cycle Assessments & Recycling
10.3Using Materials
10.4The Haber Process & NPK Fertilisers
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