1.2 AS Level

Isotopes

6 flashcards to master this topic

Definition Flip

Define the term 'isotope' in terms of the number of protons and neutrons.

Answer Flip

Isotopes are atoms of the same element with the same number of protons but a different number of neutrons. This results in the same atomic number but a different mass number.

Definition Flip

Explain the notation <sup>A</sup><sub>Z</sub>X for an isotope, clarifying what 'A' and 'Z' represent.

Answer Flip

In the notation <sup>A</sup><sub>Z</sub>X, 'A' represents the mass number (number of protons + neutrons, also known as the nucleon number) and 'Z' represents the atomic number (number of protons). X is the element symbol.

Key Concept Flip

Why do isotopes of the same element have the same chemical properties?

Answer Flip

Isotopes of the same element have the same number of electrons and the same electronic configuration. Chemical properties are determined by the number and arrangement of electrons; therefore isotopes react similarly.

Key Concept Flip

Why do isotopes of the same element exhibit different physical properties?

Answer Flip

Isotopes have different physical properties (such as mass and density) because they contain different numbers of neutrons. These differences in neutron number affect the mass of the atom and subsequently macroscopic properties dependent on mass.

Definition Flip

Describe the difference between the mass number and the atomic number of an isotope.

Answer Flip

The mass number is the total number of protons and neutrons in the nucleus of an atom. The atomic number is the number of protons in the nucleus of an atom, defining the element's identity. The number of neutrons is found by subtracting the atomic number from the mass number.

Definition Flip

Give an example of two isotopes of carbon, showing their mass and atomic numbers.

Answer Flip

Carbon-12 (<sup>12</sup><sub>6</sub>C) and Carbon-14 (<sup>14</sup><sub>6</sub>C) are isotopes of carbon. Both have 6 protons (atomic number = 6), but Carbon-12 has 6 neutrons (mass number = 12) and Carbon-14 has 8 neutrons (mass number = 14).

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1.1 Particles in the atom and atomic radius 1.3 Electrons, energy levels and atomic orbitals