2.1 Atomic & Electronic Structure

A sample of element Z was extracted from a meteorite. The table shows the relative abundance of each isotope in a mass spectrum of this sample of Z. Calculate the relative atomic mass of Z and suggest an identity of Z. Give your answer to 1 d.p. 

[3]

A naturally occurring sample of the element boron, B, has two isotopes of mass 10 and 11, and a relative atomic mass of 10.8.

Calculate the relative abundances of both isotopes in the sample of boron, B.

Give the full electron configuration of the Cu⁺ ion. 

Calculate the percentage abundance of ⁶³Cu with a mass of 62.9296 and ⁶⁵Cu with a mass of 64.9278, when the average mass of the Cu isotope is 63.546. Give your answer to an appropriate number of significant figures.

The diagram below shows electron transitions in a hydrogen atom in two regions of the electromagnetic spectrum.

Using section 3 of the Data booklet, predict which electron transition is most likely to correspond to the emission of red light.

Using sections 1 and 3 of the data booklet, predict which electron transition will correspond to the greatest frequency of light emitted.

The wavelengths of the first four lines for the Balmer series are shown below.

Using section 1 of the Data booklet, determine the ratio of the frequencies H_α to H_γ to 2 decimal places.

2-chloro-2-methylbutane contains some molecules with a molar mass of approximately 106 g mol^-1  and some with a molar mass of approximately 108 g mol^-1.

Outline why there are molecules with different molar masses.

Outline why the chlorine atom has a smaller atomic radius than the sulfur atom.

The mass spectrum of chlorine gas is shown.

 Outline the reason for the two peaks at m/z=35 and 37.

Explain the presence and relative abundance of the peak at m/z=74.

Nitrous oxide is used as a sedative in dentistry and has the formula N₂O.
Different sources of N₂O contain different ratios of ¹⁴N and ¹⁵N.           

State the name of the instrument used to distinguish between ¹⁴N and ¹⁵N and outline two characteristic differences seen in the analysis of ¹⁴N and ¹⁵N.

A sample of nitrous oxide was enriched so that it contained 4% by mass of ¹⁵N. Calculate the relative molecular mass of the resulting nitrous oxide.

Predict and explain, giving two reasons, how the first ionization energy of ¹⁵N would be different to ¹⁴N.

An atom has twice as many protons, and twice as many neutrons, as an atom of ¹⁵N.

Determine the chemical symbol for this atom, including the mass number, and deduce the number of electrons.

The element chromium has several naturally occurring isotopes whose abundances are shown in Table 1.

Table 1

Calculate the relative atomic mass of chromium to two decimal places.

State the full electron configuration for chromium.

State the meaning of [Ar] and complete the orbital diagram shown below for chromium.

Figure 1

This question is about the chromium(III) ion, .

This question is about line emission spectra of elements.

The visible line emission spectrum of hydrogen is shown below in Figure 1 and the wavelengths of the first four lines are listed in Table 1.

Figure 1

The visible line emission spectrum hydrogen

 Table 1

Draw the shape of a 1s atomic orbital and 2p atomic orbital.    

Describe the relationship between colour, energy, frequency, and wavelength in the visible spectrum.

Electron configurations give you a summary of where you can find an electron around the nucleus of an atom. They can also be determined for an ion after an atom loses or gains electrons.

State the full electron configuration of the rubidium ion, . 

The element rubidium has two naturally occurring isotopes of ⁸⁵Rb and ⁸⁷Rb. The relative atomic mass of rubidium is 85.47. Calculate the percentage abundance of each isotope.

The electrons in an atom are found in orbitals around the nucleus, which have different energy levels sometimes called shells.

Rubidium forms an ionic compound with selenium, Rb₂ Using boxes to represent orbitals and arrows to represent electrons, sketch the orbital diagram of the valence shell of selenium on the axis provided.

Figure 1