Atoms, ions, and compounds

Question 1

Relative isotopic mass

Answer 1

The mass of an atom of an isotope compared with one-twelfth of the mass of carbon-12.

Question 2

Relative atomic mass

Answer 2

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.

Question 3

Empirical formula

Answer 3

The formula that shows the simplest whole-number ratio of atoms of each element present in a compound.

Question 4

Molecular formula

Answer 4

A formula that shows the number and type of atoms present in a molecule.

Question 5

Mass spectroscopy

Answer 5

1. Sample placed in spectrometer
2. Sample is vaporised and ionised to form positive ions
3. Ions are accelerated; heavier ions move slower and are more difficult to deflect than lighter ions, so get separated
4. Ions detected by spectrometer as a mass:charge ratio (m/z); each ion reaching detector adds to signal, so isotopes higher in abundance have a larger signal