Atomic Structure and Nuclear Chemistry Flashcards
Why are atoms neutral?
They have the same number of protons and electrons
What happens to an atom if you change the number of protons or electrons?
You get a charged ion
What is the atomic number (Z)?
The number of protons in the nucleus of the atom
What is the mass number (A)?
The sum of protons and neutrons in the nucleus (nucleon number)
How are electrons arranged?
They surround the nucleus in orbitals and orbitals are grouped into families called shells
What are orbitals?
Specific regions of space
What do atoms with the same number of outermost electrons have in common?
Outermost electrons determine the properties of an atom, they will have similar reactivity and ability to form bonds
What is an isotope?
Atoms with the same atomic number but a different mass number (or the same number of protons but a different number of neutrons)
Do different isotopes of an atom have identical chemical properties?
Yes, they have the same outer electrons and chemical identity
What is the kinetic isotope effect?
Means heavier isotopes react slightly more slowly
What differs between isotopes of the same atom?
Physical properties such as density
What are the three isotopes of Hydrogen and give a use of each isotope
H-1 (Protium): most abundant isotope
H-2 (Deuterium): Used in isotopic labelling experiments; very useful in NMR spectroscopy
H-3 (Tritium): Radioactive; used in labelling experiments
What are the isotopes of chlorine?
Cl-35 and Cl-37
What are the isotopes of bromine?
Br-79 and Br-81 and at least 23 further unstable isotopes
How is RAM calculated in terms of isotopes?
It’s the weighted average of the individual isotopes
How is RAM of chlorine calculated?
There are 3 atoms of Cl-35 to every 1 atom of Cl-37 in ordinary chlorine.
So, (3x35) + (1x37)/4 = 35.5
Describe a stable isotope
Remain unchanged indefinitely
Describe an unstable isotope
Undergo spontaneous disintegration in order to become a stable nucleus.
Disintegration results in emission of small particles and/or radiation.
Also called radioactive isotopes
What is a feature of both unstable and stable isotopes?
Both can be used as diagnostic tools and tracers in scientific research
What is mass spectrometry?
Measures the molecular weight of atoms or compounds by observing the mass to charge ratio (m/z) of atoms
How does mass spectrometry work?
Atoms and molecules are converted into ions, which can be separated on the basis of their masses and motions in magnetic or electrical fields
Does mass spectrometry work for unstable or stable isotopes?
Both
What are applications of mass spectrometry?
Determining isotopic abundances and the identity of small molecules and proteins
