Unit 3 Flashcards
Internal structure of atoms
What constitutes an alpha particle?
A helium nucleus (two protons, two neutrons)
What does the term quantisation mean?
Can only have abrupt, discrete values
Can an electromagnetic field direct a neutron?
A neutron cannot be deflected by and electromagnetic field as it has no charge
What is a cathode ray?
A beam of electrons
What is an isotope?
An element with the same atomic number (proton#) but different mass number(protons+ neutrons) so it has a different amount of neutrons
Equation for speed of light?
Frequency X Wavelength
Energy=
frequency X Plancks
Energy (using wavelength)=
Speed of light X plancks/ wavelength
What governs chemical properties of an element? Atomic number or atomic mass?
The atomic number. The protons govern its properties. This is why isotopes have many of the same properties, despite different #neutrons
What do isotopes of an element have in common?
Number of protons
What is the anti-particle counterpart of the electron?
The positron
Geiger and Marsden directed a beam of alpha particles at metal foil, the fact that they deflected means what?
That there was a dense centre of positive charge.
What is Einsteins equation?
E=m x c ²
What did Dalton think Atoms were distinguished by?
Weight
What do magnets do to the path of electrons?
Make them move in a curved path
What did Millikans oil drop experiment show?
Charges on drops of oil were always a whole number multiple of -1.6x10-19 . (charge of an electron)
What does speed of light =
frequency X wavelength
E=
h X f
What does quantised mean?
Comes in well defined quantities. Values are abrupt
What must match for electrons to be promoted?
the energy difference between energy levels must be the same as the incoming energy
What is mass defect?
it is the fact that the mass of individual protons neutrons… weigh less than the experimentally found mass of the atom
Why is there a mass defect?
Some energy must be used in order to keep protons and neutrons separate
How was the proton discovered?
Fired a particles at gold foil and found some had large deflection angles which meant that there was a dense centre of positive charge
How was the neutron discovered
fired a particles at beryllium nothing was detected but when a block of paraffin was placed between the beryllium and the detector particles were detected.
Neutrons have no charge but could knock out other particles
How do you work out average mass of isotopes?
(mass# X proportion/100) + (mass# X proportion/100)
On periodic table what does period show?
The number of shells (energy levels)
on periodic table what does group show?
Number of valence electrons
