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Paper 1
Atomic Structure and Periodic Table
Both
Use atomic and mass numbers to find particle counts.
Key Facts
- Period number = number of electron shells.
- Group 0 elements are noble gases and are unreactive.
Topics Covered
Atoms and Isotopes
What you need to know
- •Atoms have protons, neutrons, and electrons.
- •Isotopes have the same protons but different neutrons.
Exam Tips
- Use atomic number for protons and mass number for protons + neutrons.
Electron Configuration
What you need to know
- •Electrons fill shells 2,8,8 for first 20 elements.
- •Group number equals outer shell electrons.
Exam Tips
- Use dot and cross diagrams for ionic bonding.
Key Terms
Atomic number
Number of protons in the nucleus.
Mass number
Number of protons plus neutrons.
Isotope
Same element with different numbers of neutrons.
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Common Exam Questions
An atom has mass number 23 and atomic number 11. How many neutrons?
2 markseasyPaper 1
Model Answer
12
What examiners want to see
- ✓Subtract atomic number from mass number.
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