CIE iGCSE Co-ordinated Sciences-C2.3 Isotopes- Study Notes- New Syllabus
CIE iGCSE Co-ordinated Sciences-C2.3 Isotopes – Study Notes
CIE iGCSE Co-ordinated Sciences-C2.3 Isotopes – Study Notes -CIE iGCSE Co-ordinated Sciences – per latest Syllabus.
Key Concepts:
CIE iGCSE Co-Ordinated Sciences-Concise Summary Notes- All Topics
Isotopes
Isotopes are atoms of the same element that contain the same number of protons (same atomic number) but differ in the number of neutrons. This results in different mass numbers for each isotope.
Examples:
- Carbon-12 (\( ^{12}\text{C} \)) → 6 protons, 6 neutrons
- Carbon-13 (\( ^{13}\text{C} \)) → 6 protons, 7 neutrons
- Carbon-14 (\( ^{14}\text{C} \)) → 6 protons, 8 neutrons
Example
Explain why Carbon-12 and Carbon-14 are isotopes of the same element.
▶️ Answer/Explanation
Both Carbon-12 and Carbon-14 have 6 protons, so they are the same element (carbon). However, Carbon-12 has 6 neutrons, while Carbon-14 has 8 neutrons. The difference in neutrons gives them different mass numbers (12 and 14), making them isotopes of carbon.
Same chemical properties of isotopes
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Because chemical properties depend on the number and arrangement of electrons:
- All isotopes of an element have the same number of electrons.
- Electrons occupy the same shells and have the same configuration.
- Therefore, isotopes undergo the same chemical reactions and form the same compounds, even though their physical properties (like mass or stability) may differ.
Example
Explain why Carbon-12 and Carbon-14 react identically with oxygen.
▶️ Answer/Explanation
Both Carbon-12 (\( ^{12}\text{C} \)) and Carbon-14 (\( ^{14}\text{C} \)) have 6 electrons arranged in the same configuration (2,4). The chemical properties of carbon depend on the valence electrons (outer shell electrons), which are the same for both isotopes. Therefore, both isotopes react identically with oxygen to form carbon dioxide (\( \text{CO}_2 \)), despite having different numbers of neutrons.
Symbols for atoms and ions
Atomic and ionic symbols provide information about the number of protons, neutrons, and electrons:
- The subscript (bottom number) is the atomic number, representing the number of protons. In a neutral atom, it also equals the number of electrons.
- The superscript (top number) is the mass number, representing the total number of protons and neutrons in the nucleus.
- An ion is an atom that has gained or lost electrons, indicated by a charge symbol (\( + \) or \( – \)) next to the element symbol. A negative charge means extra electrons, and a positive charge means electrons are missing.
Examples:
- \( ^{12}_6\text{C} \) – Carbon atom: 6 protons, 6 neutrons (12 − 6), 6 electrons.
- \( ^{35}_{17}\text{Cl}^- \) – Chloride ion: 17 protons, 18 neutrons (35 − 17), 18 electrons (1 extra due to negative charge).
Example
Given \( ^{23}_{11}\text{Na}^+ \), identify the number of protons, neutrons, and electrons.
▶️ Answer/Explanation
Protons = 11 (atomic number)
Neutrons = 23 − 11 = 12
Electrons = 11 − 1 = 10 (because of the positive charge)
This shows how atomic and ionic symbols convey detailed information about subatomic particles.