atomic and radiation Flashcards
describe the structure of the atom
Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The numbers of subatomic particles in an atom can be calculated from its atomic number and mass number. An atom has a central nucleus.
what is the change and mass of each of the particles in the atom
positive :1,1
negative :1,0
neutral:0,1
what are the size of the atom and nucleus
The diameter of a nucleus is about 2 × 10-15 m and the diameter of an atom is 1 × 10-10 m. What size would the atom be in a model where the Earth represented the nucleus? The diameter of the Earth is 1.3 × 107 m. Therefore the atom is 5 × 104 larger than the nucleus.
where is the most of the mass of the atom located
nucleus
describe the different parts of an element symbol
For example the symbol O represents an atom of oxygen, and Na represents an atom of sodium. You must write the chemical symbol of sodium as Na, not as NA, na or nA.
describe what happened in Rutherford’s alpha particle scattering experiment
Rutherford Alpha Particle Scattering Experiment. Rutherford’s alpha particle scattering experiment changed the way we think of atoms. Before the experiment the best model of the atom was known as the Thomson or “plum pudding” model. The atom was believed to consist of a positive material “pudding” with negative “plums” distributed throughout.
how did the gold foil experiment show that most of the atom is made of empty space
Rutherford’s gold foil experiment showed that atoms are mostly empty space, with the positive charge concentrated in a nucleus. He realized this because most of the alpha particles passed straight through the piece of gold foil, with just a few deflected at huge angles.
how did the gold foil experiment show that most of the mass is in a positive nucleus at the centre of the atom
Ernest Rutherford, originally from New Zealand, is credited as being the father of nuclear physics for his discoveries in atomic structure, even though Hantaro Nagaoka, a physicist from the Imperial University of Tokyo, first proposed the theory of the nucleus as it is known today. Rutherford’s “gold foil experiment” led to the discovery that most of an atom’s mass is located in a dense region now called the nucleus. Prior to the groundbreaking gold foil experiment, Rutherford was granted the Nobel Prize for other key contributions in the field of chemistry.
what did each of these people discover about the atom
a) James Chadwick
b) Nils bohr
a) In 1932 James Chadwick found evidence for the existence of particles in the nucleus with mass but no charge. These particles are called neutrons. This led to another development of the atomic model, which is still used today.
b) The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element.
what is alpha radiation made out of
Alpha radiation consists of helium-4 nucleus and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons, is halted by an aluminium plate.
what is beta radiation made out of
Beta radiation, consisting of electrons or positrons, is stopped by a thin aluminum plate, but gamma radiation requires shielding by dense material such as lead or concrete.
what is a gamma radiation made out of
A gamma ray, or gamma radiation (symbol γ or ), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy.
order alpha, beta and gamma from most to least ionising
Radio waves, microwaves, infrared and ultraviolet. Radiation can take any form across the entire electromagnetic spectrum, most of which are invisible to the naked eye. What might be surprising to you is that the term ‘radiation’ doesn’t just encompass photons of light. Sound waves, for example, are also a form of radiation. In fact, any wave or particle is radiation! But when we hear the word ‘radiation’, our first thought goes to uranium and plutonium, among other radioactive substances.
what is beta radiation made out of
Beta radiation, consisting of electrons or positrons, is stopped by a thin aluminium plate, but gamma radiation requires shielding by dense material such as lead or concrete.
order alpha, beta and gamma from most to least ionising
alpha ,
