Key concepts in chemistry: Practice Questions

What is the relative charge and relative mass of a neutron?

A student reacts 24g of magnesium with 16g of oxygen in a closed system. According to the law of conservation of mass, what is the total mass of magnesium oxide produced?

An element has two isotopes: \( ^{63}\text{Cu} \) with an abundance of 69% and \( ^{65}\text{Cu} \) with an abundance of 31%.
Calculate the relative atomic mass (\( A_r \)) of this element to 2 decimal places.

A sample of a hydrocarbon is burnt. 4.8g of carbon reacts with 1.2g of hydrogen.
What is the empirical formula of this hydrocarbon?
(Relative atomic masses: C = 12, H = 1)

Explain why atoms contain an equal number of protons and electrons.

Describe how Dmitri Mendeleev used his periodic table to predict the existence and properties of elements that had not yet been discovered.

Deduce the empirical formula of a compound that contains \(2.4\text{ g}\) of carbon and \(0.8\text{ g}\) of hydrogen. (Relative atomic masses: \(\text{C} = 12\), \(\text{H} = 1\))

a) Describe the structure of an atom in terms of the position, relative charge, and relative mass of protons, neutrons, and electrons.
b) A sample of neon contains two isotopes: \(^{20}\text{Ne}\) and \(^{22}\text{Ne}\). The relative abundance of \(^{20}\text{Ne}\) is 90% and the relative abundance of \(^{22}\text{Ne}\) is 10%. Calculate the relative atomic mass of this sample of neon.
c) Explain why the electronic configuration of neon, which is 2.8, makes it an unreactive element in Group 0.