atomic structure Flashcards
describe Dalton’s atomic theory
-atoms=tiny particles made of elements
-atoms cannot be divided
-all atoms in an element are the same
-atoms of one element are different to those of other elements
what did Thompson discover about electrons
-negative charge
-can be deflected by electromagnetic fields
-very small mass
explain current model of the atom
-protons & neutrons found in nucleus
-electrons orbit nucleus in shell
-nucleus=tiny compared to total vol of atom
-most of atom’s mass is in the nucleus
-most of atom=empty space beween nucleus and electrons
charge of proton and electron
electron= -1
proton= +1
which particle has the same mass as a proton
neutron
which particles make up most of atom’s mass
protons and neutrons
what does atomic number tell us about element
number of protons in an atom
how is mass number calculated
mass number= protons + neutrons
isotope definition
atoms of the same element with different number of neutrons (and mass number) but same number of protons (atomic number)
why do different isotopes of the same element react in the same way.
-neutrons have no impact on chemical activity
-reactions involve electrons, isotopes have the same electronic configeration
why do different isotopes of the same element react in the same way.
-neutrons have no impact on chemical activity
-reactions involve electrons, isotopes have the same electronic configuration
define relative atomic mass
weighted mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12
define relative isotopic mass
mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12.
relative isotopic mass is the same as which number
mass number
what 2 assumptions are made when calculating mass number
-contribution of electron is neglected
-mass of both proton and neutron is taken as 1.0 u
3 uses of mass spectrometry
-identify unknown compounds
-find relative abundance of each isotope of an element
-determine structural information
what does the principal quantum number indicate
shell occupied by the electrons
shell definition
group of orbitals with the same principal quantum number
how many electrons can the 1st shell hold
2
how many electrons can the 2nd shell hold
8
how many electrons can the 3rd shell hold
18
how many electrons can the 4th shell hold
32