s1.2 the nuclear atom Flashcards
what is the structure of an atom?
protons and neutrons (nucleons) are located in the nucleus of the atom. the nucleus is very dense as it contains almost all of the mass of an atom.
the electrons are located in energy levels (principal energy levels) within the atom. atoms are electrically neutral because they have the same number of protons and electrons
what are ions?
ions are an electrically charged species that have either gained or lost electrons
cations are positive, anions are negative
what are isotopes?
isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons
what are the physical and chemical properties of isotopes?
isotopes have the same number of electrons, therefore they have identical chemical properties.
isotopes have different numbers of neutrons, meaning their masses are different. therefore, they have different physical properties, such as density and boiling point
what is relative atomic mass?
the relative atomic mass is the weighted average mass of the naturally occurring isotopes of an element relative to 1/12 the mass of an atom of carbon-12
relative atomic masses do not have units because it is a relative scale
what is a mass spectrometer?
a mass spectrometer is used to determine the isotopes of an element, together with their relative abundances. the relative abundance of an isotope is the percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element
what does a mass spectrometer produce?
a mass spectrometer produces a mass spectrum which shows relative abundance on the y-axis against mass to charge ratio (m/z) on the x-axis
how do you calculate relative atomic mass through relative abundance?
to calculate the relative atomic mass of an element, multiply the mass of each isotope by its relative abundance, add together for all the isotopes, and then divide by 100
what is relative abundance?
relative abundance is the percentage of an isotope in a naturally occurring sample of the element
what is relative intensity?
relative intensity is the amount of an ion produced in relation to the most abundant ion (the base peak) which is assigned a relative intensity of 100
how to calculate the relative intensity of ions that aren’t the base peak?
intensity = (100 / abundance of base peak) x abundance of other ion
how to calculate relative atomic mass through relative intensity?
Ar = (m/z x relative intensity) + (base peak m/z x 100) / (relative intensities added up)
