What are the charge and mass of a neutron?

0 C and 1.67×10⁻²⁷ kg (almost the same as a proton).

What are the charge and mass of an electron?

−1.60×10⁻¹⁹ C and 9.11×10⁻³¹ kg.

What is the relative mass of an electron compared with a proton?

About 1/1840 (approximately 0.0005).

What do Z and A mean in nuclide notation?

Z is the proton number and A is the nucleon number (protons plus neutrons).

How many electrons does an ion of charge +2 have?

Z − 2, because it has lost two electrons.

What is specific charge?

Charge divided by mass, measured in C kg⁻¹.

Nuclei with the same proton number but different numbers of neutrons.

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

They have the same number of electrons, which determine chemical behaviour.

How is relative atomic mass found from isotopic data?

Take the weighted mean of the isotope masses using their percentage abundances.

Constituents of the atom and isotopesAQA A-Level Physics: Flashcards

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What are the charge and mass of a proton?

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What are the charge and mass of a proton?: +1.60×10⁻¹⁹ C and 1.67×10⁻²⁷ kg.
What are the charge and mass of a neutron?: 0 C and 1.67×10⁻²⁷ kg (almost the same as a proton).
What are the charge and mass of an electron?: −1.60×10⁻¹⁹ C and 9.11×10⁻³¹ kg.
What is the relative mass of an electron compared with a proton?: About 1/1840 (approximately 0.0005).
What do Z and A mean in nuclide notation?: Z is the proton number and A is the nucleon number (protons plus neutrons).
How do you find the number of neutrons in a nuclide?: N = A − Z.
How many electrons does an ion of charge +2 have?: Z − 2, because it has lost two electrons.
What is specific charge?: Charge divided by mass, measured in C kg⁻¹.
What is the specific charge of a proton?: 9.58×10⁷ C kg⁻¹.
What is the specific charge of an electron?: 1.76×10¹¹ C kg⁻¹.
What are isotopes?: Nuclei with the same proton number but different numbers of neutrons.
Why do isotopes of an element have the same chemical properties?: They have the same number of electrons, which determine chemical behaviour.
How is relative atomic mass found from isotopic data?: Take the weighted mean of the isotope masses using their percentage abundances.

Exam questions on Constituents of the atom and isotopes

A student studies the structure of lithium. A neutral atom of lithium-7 is written $^{7}_{3}\mathrm{Li}$ . Use e = 1.60×10⁻¹⁹ C.
Another isotope of lithium is $^{6}_{3}\mathrm{Li}$ . State the number of protons, neutrons and electrons in a neutral atom of this isotope.2 marks
Chlorine, proton number 17, occurs naturally as two stable isotopes, chlorine-35 and chlorine-37. In sodium chloride chlorine forms chloride ions, Cl⁻.
State one way in which atoms of chlorine-35 and chlorine-37 are the same and one way in which they differ, in terms of particles.2 marks
Naturally occurring chlorine consists of 75.8% chlorine-35 and 24.2% chlorine-37 by number of atoms. Use e = 1.60×10⁻¹⁹ C and take the mass of a nucleus to be the number of nucleons multiplied by 1.67×10⁻²⁷ kg.
Calculate the relative atomic mass of naturally occurring chlorine.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).