Atomic Structure Flashcards
In the nucleus, there is…
Neutrons and protons
Most of the mass in the atom is because?
Nucleus (protons and neutrons)
How do electrons move?
In orbitals
The orbitals in an atom take up?
Most of the volume
The diameter of the nucleus is what compared to the rest of the atom?
Very small
What is the relative mass and charge of protons?
1 and +1
What is the relative mass and relative charge of a neutron?
1 and 0
What is the relative mass and charge of an electron?
1/2000 and -1
What does the mass number tell you?
Total number of neutrons and protons
What does the atomic number tell you?
The number of protons
For neutrally charged atoms, what can we say about the number of protons and neutrons?
They are equal
If they atom is charged, what can we say about the number of protons and electrons?
They are unequal
In a positively charged ion, there are
More protons than electrons
In a negatively charged ions, there are
More electrons than protons
Define isotope
Atoms with the same number of protons and electrons but different number of neutrons
Do isotopes have the same chemical properties? Why?
Yes
The same number and arrangement of electrons i.e the same electron configuration
Do isotopes have the same physical properties? Why?
No, but only slightly
Depends on mass of an atom
Examples of how physical properties of an isotopes differ
Different densities, rates of diffusion
What was Dalton’s model of an atom like?
Solid spheres
Different spheres make up the different elements
What was Thompson’s model of the atom like?
Came up with the ‘plum pudding’ model
Discovered electrons
Electrons were surrounded by positively charged ‘pudding’
What was Rutherford’s model of an atom like?
Tiny positively charged nucleus surrounded by a ‘cloud’ of negative electrons. Most of the atom was empty space
How did Rutherford prove that Thompson’s plum pudding model was wrong?
Through the gold foil experiment
If Thompson’s model was right, what would the experiment shown? Explain why
That all of the alpha particles would be deflected
The positive alpha particle would be repelled by the positive atom
What actually happened during the gold foil experiment?
Most of the particles went straight through the foil with only a small number being deflected backwards
What was Rutherford’s model called?
Nuclear model of the atom
What was wrong with Rutherford’s model?
The cloud of electrons would collapse into the nucleus, causing the atom to dissipate
What did Bohr propose in his model?
That electrons are split into orbitals of fixed energy.
What happens when an electron moves across a shell?
Electromagnetic radiation is absorbed or emitted