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Chemistry

Atomic Structure & Periodic Table

Key Points

  • Atomic number = protons = electrons (neutral atom)
  • Mass number = protons + neutrons
  • Isotopes: same Z, different A (different neutron count)
  • Atomic radius decreases across period, increases down group
  • Ionisation energy increases across period, decreases down group

Practice Questions

3 questions
1

An element has atomic number 17 and mass number 35. How many neutrons does it have?

2

Which of the following is NOT a property of isotopes?

3

Which of the following elements is in Period 3 of the periodic table?

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Chemical Bonding