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Edexcel GCSE Physics Your notes
6.1 Atomic Structure
Contents
6.1.1 Inside the Atom
6.1.2 Protons, Neutrons & Electrons
6.1.3 Atomic & Mass Number
6.1.4 Isotopes
6.1.5 Electron Structure
6.1.6 Positive Ions
6.1.7 Developing Models of the Atom
Page 1 of 27
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6.1.1 Inside the Atom
Your notes
Inside the Atom
Atoms are the building blocks of all matter
Atoms have a tiny, dense, positively charged nucleus at their centre, with negatively charged
electrons orbiting around the nucleus
The radius of the nucleus is over 10,000 times smaller than the whole atom, but it contains almost all of
the mass of the atom
Diagram showing the structure of a Lithium atom. If drawn to scale then the electrons would be around
100 metres away from the nucleus!
Parts of the Atom
The nucleus contains:
Protons - positively charged particles with a relative atomic mass of one unit
Neutrons – no charge, and also with a relative atomic mass of one unit
Almost all of the atom is empty space, but moving around the nucleus there are:
Electrons – negative charge with almost no mass (1/2000 the mass of a proton or neutron)
Page 2 of 27
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The Size of the Atom
Atoms are incredibly small, with a radius of only 1 × 10-10 m Your notes
This is 0.0000000001 m when written without standard form
This means that about one hundred million atoms could fit side by side across your thumbnail
A group of atoms can bond together to make molecules, such as water
A water molecule is comprised of two hydrogen atoms and one oxygen atom
A 200 ml glass of water will contain approximately 7,000,000,000,000,000,000,000,000 water
molecules!
Exam Tip
There are many different models of the atom. As you progress through the topic you will discover that
the atom can be described in many different ways, such as the Plum Pudding Model that is covered
later, but for your exam, make sure to only use the model and descriptions described here.
Page 3 of 27
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Edexcel GCSE Physics Your notes
6.1 Atomic Structure
Contents
6.1.1 Inside the Atom
6.1.2 Protons, Neutrons & Electrons
6.1.3 Atomic & Mass Number
6.1.4 Isotopes
6.1.5 Electron Structure
6.1.6 Positive Ions
6.1.7 Developing Models of the Atom
Page 1 of 27
© 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers
, Head to www.savemyexams.com for more awesome resources
6.1.1 Inside the Atom
Your notes
Inside the Atom
Atoms are the building blocks of all matter
Atoms have a tiny, dense, positively charged nucleus at their centre, with negatively charged
electrons orbiting around the nucleus
The radius of the nucleus is over 10,000 times smaller than the whole atom, but it contains almost all of
the mass of the atom
Diagram showing the structure of a Lithium atom. If drawn to scale then the electrons would be around
100 metres away from the nucleus!
Parts of the Atom
The nucleus contains:
Protons - positively charged particles with a relative atomic mass of one unit
Neutrons – no charge, and also with a relative atomic mass of one unit
Almost all of the atom is empty space, but moving around the nucleus there are:
Electrons – negative charge with almost no mass (1/2000 the mass of a proton or neutron)
Page 2 of 27
© 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers
, Head to www.savemyexams.com for more awesome resources
The Size of the Atom
Atoms are incredibly small, with a radius of only 1 × 10-10 m Your notes
This is 0.0000000001 m when written without standard form
This means that about one hundred million atoms could fit side by side across your thumbnail
A group of atoms can bond together to make molecules, such as water
A water molecule is comprised of two hydrogen atoms and one oxygen atom
A 200 ml glass of water will contain approximately 7,000,000,000,000,000,000,000,000 water
molecules!
Exam Tip
There are many different models of the atom. As you progress through the topic you will discover that
the atom can be described in many different ways, such as the Plum Pudding Model that is covered
later, but for your exam, make sure to only use the model and descriptions described here.
Page 3 of 27
© 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers
