atomic structure Flashcards
ion definition
an atom or a group of atoms that have an electrical charge either positive or negative
isotope definition
atoms of the same element with different numbers of neutrons and different masses
why do isotopes have the same chemical properties?
because they have the same electronic structure
relative isotopic mass definition
the mass of an atom of an isotope compared to 1/12th of the mass of a carbon-12 atom
relative atomic mass definition
the weighted mean mass of an atom of an element compared to 1/12th of the mass of a carbon-12 atom
difference between RAM and mass number?
mass no. = no of protons + neutrons
a whole number
applies to a specific isotope
not found in the periodic table
top left of element symbol
RAM is an average mass
not a whole number
larger no. given in a periodic table
can be written in different places
what is the term “relative formula mass” used for?
- compounds with giant structures
what is the term “relative molecular mass” used for?
simple molecules
what is the molecular formula?
total number of atoms of each element in each molecule in a substance
what is a mass spectrometer?
used to find the percentage abundance of isotopes in a sample of an element
how does a mass spectrometer work?
- sample placed into mass spectrometer
- sample undergoes vaporisation (l - g)
- then it undergoes ionisation to form a + ion
- ion is accelerated - ions of each isotope separate as heavier ions will move more slowly
- ions are deflected - size of deflection depends on the ratio of the ions mass to charge
- ions are detected on the mass spectrum as their m/z ratio - the greater the abundance, the larger the signal
what’s the mass to charge ratio equation?
relative mass of an ion ÷ relative charge on ion
what is a binary compound?
a compound that contains only two elements
what is a polyatomic ion?
an ion that contains atoms of more than one element eg OH-
