Isotopes are different versions of the same element that pop...
Chemistry796 views·Updated 21 Sept 2026·1 pageUnderstanding Isotopes - GCSE C1 Chemistry Revision Guide
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Isotopes: Same Element, Different Mass
Ever wondered why some atoms of the same element can have different weights? Isotopes are simply different forms of the same element that contain the same number of protons but different numbers of neutrons.
Think of isotopes as siblings in the same family - they share the family name (element) but have slightly different characteristics. Since they have the same number of protons, isotopes always have the same atomic number but different mass numbers.
Take carbon as a perfect example: Carbon-12 has 6 protons, 6 electrons, and 6 neutrons, whilst Carbon-13 has 6 protons, 6 electrons, but 7 neutrons. Both are carbon, but Carbon-13 is slightly heavier due to that extra neutron.
You can calculate the relative atomic mass using this handy equation: relative atomic mass = (sum of isotope abundance × isotope mass number) ÷ (sum of abundances of all isotopes). This formula helps you work out the average mass of all isotopes of an element.
Quick Tip: Isotopes can have different physical properties - heavier isotopes often have higher melting points, boiling points, and densities than their lighter cousins!
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Chemistry796 views·Updated 21 Sept 2026·1 pageUnderstanding Isotopes - GCSE C1 Chemistry Revision Guide
Alyssa@alyssa_jayne
Isotopes are different versions of the same element that pop up everywhere in chemistry - from carbon dating to nuclear medicine. Understanding how they work is crucial for mastering atomic structure and chemical calculations.
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Isotopes: Same Element, Different Mass
Ever wondered why some atoms of the same element can have different weights? Isotopes are simply different forms of the same element that contain the same number of protons but different numbers of neutrons.
Think of isotopes as siblings in the same family - they share the family name (element) but have slightly different characteristics. Since they have the same number of protons, isotopes always have the same atomic number but different mass numbers.
Take carbon as a perfect example: Carbon-12 has 6 protons, 6 electrons, and 6 neutrons, whilst Carbon-13 has 6 protons, 6 electrons, but 7 neutrons. Both are carbon, but Carbon-13 is slightly heavier due to that extra neutron.
You can calculate the relative atomic mass using this handy equation: relative atomic mass = (sum of isotope abundance × isotope mass number) ÷ (sum of abundances of all isotopes). This formula helps you work out the average mass of all isotopes of an element.
Quick Tip: Isotopes can have different physical properties - heavier isotopes often have higher melting points, boiling points, and densities than their lighter cousins!
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