MODULE 2 - 2.1.1 atomic structure & isotopes Flashcards
Where is most of the mass of an atom located?
The nucleus
What is the nucleus made of?
Protons and electrons
Relative charge and mass of a proton?
+1 and 1
Relative charge and mass of a neutron?
0 and 1
Relative charge and mass of an electron?
-1 and 1/1836
What is the mass number?
on top of the element. Tells us p+ and e- number
What is the atomic number
Proton number
Why are all atoms neutral?
Number of protons = number of electrons
How to find number of neutrons?
Mass # - atomic #
What are ions
Atoms that have lost or gained electrons
What are isotopes
Atoms of the same element with the same number of protons but a different number of neutrons
History of the atom: What did John Dalton discover
Atoms are spheres and each element is made from different spheres
History of the atom: What did JJ Thompson discover
Electrons and plum pudding model. Atom wasn’t solid
History of the atom: What did Rutherford discover
Nucleus. That it was small and positively charged. The atom was mainly empty space making a negative cloud
What was Rutherford’s gold leaf experiment
Fired + alpha particles at thin golf leaf. Most went through but some deflected (hit a + nucleus)
History of the atom: What did Niels Bohr discover
Criticised Rutherford. Existence of fixed electron shells
Proof of Bohr’s electron shells?
When EM radiation is absorbed, electrons move between shells and emit radiation as they move to lower energy shells
Relative atomic mass (Ar)
The weighted mean mass of an atom of an element, relative to 1/12th of the mass of a carbon-12 atom
Relative isotopic mass
The mass of an isotope relative to 1/12th of the mass of a carbon-12 atom
Relative molecular mass (Mr)
The mean mass of a molecule relative to 1/12th of the mass of a carbon-12 atom
Mass spectra: How to calculate relative atomic mass (Ar) from a graph
Ar = (% abundance x mass of isotope) + (% abundance x mass of isotope)/ 100
