The atom

The hydrogen isotopes $^{1}_{1}\text{H}$ and $^{2}_{1}\text{H}$ are shown here. Fig. 8.1 contains a table for the counts of protons and neutrons in one nucleus of each isotope.

May/June 2015

Gold’s only stable isotope, Au, contains 79 protons and 118 neutrons in the nucleus of an atom. How many electrons are there in a neutral atom of this isotope?

May/June 2023

Which particle is the lightest?

May/June 2024

Which row indicates the sign of the charge on an atom's nucleus and the sign of the charge carried by an electron?

May/June 2025

Which number is always the same as the proton number of a neutral atom belonging to a radioactive isotope?

Oct/Nov 2016

Which row represents the atomic structure of a neutral atom with a nucleon number of $9$?

Oct/Nov 2020

In the simplified model of an atom, X circles Y. What do X and Y represent?

Oct/Nov 2021

In the simple atomic model, X travels in an orbit around Y. Identify X and Y.

Oct/Nov 2021

In two different isotopes of the same element, how do the proton numbers (atomic numbers) and the nucleon numbers (mass numbers) compare?

Oct/Nov 2021

Fig. 5.1 presents a diagram showing how many particles are in a beryllium (Be) ion, which is a charged atom.

Oct/Nov 2022

Which row shows the atom’s positive and negative particles?

Oct/Nov 2024

For a particular isotope of element $Q$, the nuclide notation is $^R_ZQ$. In a neutral atom of this isotope, what is the combined total of protons, neutrons and electrons?

Oct/Nov 2024

Four statements concerning an atom are given below. Which of these statements is correct?

Oct/Nov 2025