Unit 1: sec.1 - Atomic Structure Flashcards
Give one similarity and one difference between a proton and a neutron.
Similarity: Both have a relative mass of 1
Difference: Protons have a relative charge of 1 where neutrons are neutral.
What are isotopes.
Atoms of the same element with the same number of protons, but different numbers of neutrons.
An atom has 16 protons, 18 neutrons and 16 electrons. Another atom has 16 protons, 16 neutrons and 18 electrons. Are these atoms isotopes of each other?
Yes because they have the same number of protons (16) but a different number of neutrons (16 or 18). (The second atom is also an ion because it’s number of electrons is different to it’s number of protons.
Atom a has 9 protons, 10 neutrons and 9 electrons. Atom B is an isotope of atom A. Suggest how many protons, neutrons and electrons atom B contains.
an example of atom B could be:
9 protons, 9 neutrons, 10 electrons
Atom B is an isotope of atom A, so it must have the same number of protons, but a different number of neutrons.
It’s an ion so the number of electrons must be different to the number of protons.
( >change the no. of neutrons first- to something appropriate
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Atom a has 9 protons, 10 neutrons and 9 electrons. Atom B is an isotope of atom A. Suggest how many protons, neutrons and electrons atom B contains.
an example of atom B could be:
9 protons, 9 neutrons, 10 electrons
Atom B is an isotope of atom A, so it must have the same number of protons, but a different number of neutrons.
It’s an ion so the number of electrons must be different to the number of protons.
( >change the no. of neutrons to something appropriate
Name two models which were used in the past but are no longer accepted.
the plum pudding model
rutherford’s nuclear model
How did John dalton describe atoms in the 19th century?
John Dalton said atoms were solid, indivisible spheres and that different elements were made of different spheres.
Decribe the model of the atomic structure that was developed by J.J. Thomson.
J.J. Thomson suggested that atoms were a bit like a plum pudding. He thought that atoms were made up of a positively-charged puddin, with electrons embedded in it.
In Rutherford’s gold foil experiment most of the alpha particles zoomed straight through the gold foil. Why was this?
Most of the alpha particles passed straight through as most of an atom is made up of empty space. ( instead of the +vly charged ball sphere described in the plum pudding
In Rutherford’s gold foil exp. a small number of alpha particles were deflected straight back again. How did Rutherford explain this?
Rutherford realised positively charged alpha particles that were being deflected straight back must be hitting something else positively charged. He suggested that most of the mass of an atom must be located in the centre, in a tiny, positively charged nucleus.
Atoms can absorb and emit electromagnetic radiation with a fixed energy. Explain why this observation fits the bohr model of the atom better than the nuclear model.
In the Bohr model, electrons exist in shells of fixed energies. Electrons can move between shells. When they move they absorb or emit the difference in energy between these shells as electromagnetic radiation. In the nuclear model the electrons can move around anywhere in a ‘cloud’ - so this model can’t explain why the radiation that is absorbed or emitted has a fixed energy.
What data led scientists to refine the Bohr model? How did they change it to explain this data?
scientists discovered that not all electrons in a shell have the same energy, so they refined the Bohr model to include sub-shells with different energies.
Define relative atomic mass, Ar
Relative atomic mass, Ar, is the weighted mean mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12
Describe how you could calculate the relative molecular mass, Mr of a molecule.
To find the relative molecular mass of a molecule, just add together the relative atomic masses of all the atoms in a molecule.
What is the relative molecular mass of C2H5Cl?
64.5 (2x12.0)+(5x1.0)+35.5 = 64.5
Mr = 64.5
