Atoms, ions and compounds Flashcards
Whats’s the mass of a proton
1
What’s the mass of an electron
1/1836
What’s the mass of neutron
slightly greater than a proton
What’s the charge of a proton
equal to electron but opposite
relative charge of +1
What’s the charge of a neutron
neutral no charge
What’s the charge of an electron
equal to proton but opposite
relative charge of -1
What the role of neutrons
as despite the electrostatic repulsion between protons they hold the nucleus together
As the nucleus gets larger…
… more and more neutrons are required
Isotope
atoms with the same element with the same number of protons but different numbers of neutrons and thus different masses
Atomic number
the number of protons in the nucleus of an atom
Mass number
the sum of the number of protons and neutrons present in the nucleus
ALSO KNOW AS NUCLEON NUMBER
Proton number
the number of protons present in the nucleus
Atomic number symbol
Z
Mass number symbol
A
Why do isotopes have similar chemical properties
they have the same number of electrons
the number of neutrons has no effect on an elements reactions as it doesn’t effect their electronic structure
THEREFORE different elements of isotopes react on the same way
Why is it hard to CHEMICALLY distinguish isotopes
as they have the same electronic configuration and neutrons does not effect the elements reactions
THEREFORE
they have the same number of electrons in their outer shell so they from the same ions during a chemical reaction
Why might isotopes have varying physical properties
as the increased mass may cause an increased
melting point
boiling point
density
Cations
POSITIVE IONS
- atoms with fewer electrons than proton s they have an overall positive charge
Anions
NEGAITVE IONS
- atoms with more electrons than protons they have an overall negative charge
Ion
a charged atom
Relative isotopic mass
is the mass of an isotope compared to 1/12 of the mass of a carbon 12 atom
Relative atomic mass
is the average mass of an atom of an element compared to 1/12 of the mass of a carbon 12 atom
What causes mass deflect
the strong nuclear forces holding together protons and neutrons comes at the expense of a loss of a fraction of their mass
-so the adding together the relative masses of protons neutrons and electrons a small amount of mass is lost e.g. MASS DEFLECT
How do you calculate the mass of atoms if some is lost due to mass deflect?
use the mass of a carbon 12 atom as standers
-total mass of C12
= 12u
-1u= standard weight of a proton/ neutron
What is the weighted mean mass of an atom
the relative atomic mass
What does the weighted mean mass take into account
- the percentage abundance of each isotope
- the relative isotopic mass of each isotope
How can you determine the percentage abundance of each isotope in a sample of elements
a mass spectromemter
How does a mass spectrometer work
- a sample is placed in the mass spectrometer
- the sample is vaporised then ionised to form positive ions
- the positive ions are accelerated
- as the heavier ions are slower and more difficult to deflect the ions of each isotope are separated
- the ions are detected on a mass spectrum as a mass to charge ration m/z
- the greater the abundance of ions the greater the signal
- when an ion is + the ratio=RIM
