Topic One-particles Flashcards
(46 cards)
What are the relative masses of a
proton, neutron and electron?
Proton: 1
Neutron: 1
Electron: 1/1836
What are the relative charges of a
proton, neutron and electron?
Proton: +1
Neutron: 0
Electron: -1
What is an ion?
an atom or molecule with a positive or
Negative charge.
How is an ion formed?
When an atom or molecule gains or loses electron(s), Positive ions are formed when an electron is lost.
Negative ions are formed when an electron is gained.
What does the atomic number tell you
about an element?
The atomic number is unique to each
element and tells you the number of
protons an element has.
What is the mass number?
The combined total of the number of
protons and neutrons in the nucleus of an atom of an element.
What are isotopes?
Atoms of the same element with the
same number of protons but a different number of neutrons.
How does the atomic number and mass
number differ between isotopes of the same element?
Atomic number is the same as an element always has the same number of protons.
Mass number is different as there are
different numbers of neutrons.
Why do atoms contain equal numbers of protons and electrons?
Atoms have a stable overall charge of O.
Protons are positively charged and electrons are
negatively charged so they must be present in
equal numbers for charges to balance.
How can you calculate the number of
neutrons, given the mass number and
atomic number of an element?
Number of neutrons =
mass number - atomic number
Boron has the atomic number 5 and
mass number 11. How many protons,
electrons and neutrons does boron
have?
5 protons
5 electrons
6 neutrons
Sodium has the atomic number 11 and mass number 23. How many protons, electrons and neutrons does the Na+ion have?
11 protons
10 electrons (one has been to form the positive ion)
12 neutrons
Compare the typical size of atoms and
small molecules
Atoms and small molecules are both incredibly small.
Small molecules are larger than atoms because they are
made of atoms.
The typical atomic radii and bond length are in the order
of 10-10m.
What change did Niels Bohr propose to the nuclear model of an atom?
Electron shells around the nucleus.
Describe the structure of an atom
A small central nucleus made up of protons and neutrons (positively charged). Electrons orbit (move around) the nucleus in shells (negatively charged)
Where is the mass of the atom
concentrated?
In the nucleus
Compare the sizes of the nuclear radius and the atomic radius
The nuclear radius is much smaller than the atomic radius.
Who designed and carried out the gold foil experiment?
Ernest Rutherford designed the
experiment.
Geiger and Marsden carried out the
experiment.
What did Rutherford discover from his
gold foil experiment?
He shot a beam of positively charged particles into a sheet of
gold foil.
Most particles passed straight through indicating that atoms
were mostly empty space.
A few particles were deflected and a few bounced directly
back showing that there must be a positively charged
nucleus.
Describe Rutherford’s model of the atom
Mass is concentrated in the central nucleus. Mostly empty space. Electrons travel in random paths around the nucleus.
Describe the atomic model proposed by JJ Thomson
The plum pudding model:
Negative electrons scattered through a positively charged material.
What are the three subatomic particles in an atom?
Protons
Neutrons
Electrons
Who described atoms as ‘solid spheres’?
John Dalton
What was dalton’s theory?
Atoms cannot be created, divided or destroyed.
Atoms of the same element are exactly the same an
atoms of different elements are different.
Atoms join with other atoms to make new substance
