What are the three main subatomic particles in an atom?
Proton, neutron, electron
What is the relative mass and relative charge of proton, neutron, and electron?
Proton: relative mass = 1, relative charge = +1
Neutron: relative mass = 1, relative charge = 0
Electron: relative mass = 1/2000, relative charge =-1
Where is the mass of an atom. Mostly concentrated? Why?
In the nucleus, because protons and neutrons are located there and electrons have negligible mass.
Define atomic number
Number of protons in the nucleus of an atom.
Define mass number
Total number of protons + neutrons in he nucleus.
What is an isotope?
Isotopes are atoms of the same element but different numbers of neutrons, and thus different mass numbers.
Do isotopes have the same chemical properties?
Yes, because they have the same number of electrons and the same electron configuration, so their chemistry (bonding) is identical.
Do isotopes have the same physical properties?
No, because their masses differ so physical properties vary.
Define relative isotopic mass
The mass of a particular isotope compared t the 1/12th of the mass of one atom of carbon-12.
Write the formula to calculate relative atomic mass given isotopic masses and abundances.
(Mz X %) over 100.
What is a mass spectrometer used for in this topic?
To find isotopic masses and relative abundances of isotopes in a sample, which allow calculation of relative atomic mass.
Outline the main steps in a mass spectrometer.
- Ionisations- sample atoms are ionised to form positive ions.
- Acceleration- ions are accelerated by electric fields.
- Deflection- an applied magnetic field deflects ions; degree of deflection depends on mass/charge ratio.
4.detection- ions hit a detector, producing a signal; relative heights correspond to abundence.
What is mass spectrum? What do the axes represent?
A graph with masses (m/z or isotopic mass) on the x axis and relative abundance on the y axis. Peaks correspond to isotopes present.
How would you use mass spectrometry data in an exam to find Ar?
Identify the masses of isotopes, their relative abundance, convert abundence to. Percentages, then use the weighted average formula.
Define relative molecular mass
The sum of relative atomic masses of all atoms in a molecule.
Define relative formula mass
For ionic compounds, is the sum of the relative atomic masses of all ions in its formula unit.
Why do relative masses have no units?
Because they are ratios comparing to a standard 1/12 of a carbon 12 atom, thus they are dimensionless.
What is the diference between an atoms mass number and to relative isotopic mass?
Mass number is a whole number= protons + neutrons. Relative isotopic mass is a mass on. The relative scale. Compare to 12 carbon atom
