Matter and Particles Flashcards
Which subatomic particle has a negative charge?
The electron
Which subatomic particle is uncharged?
The neutron
Which subatomic particle is not found in the nucleus?
The electron
Which subatomic particle has a positive charge?
The proton
Which subatomic particle has the smallest mass?
The electron
Which subatomic particles are found in the nucleus?
Protons and neutrons
Which subatomic particles are found orbiting the nucleus?
Electrons
The ‘atomic number’ of a nucleus tells you the number of which subatomic particle?
The atomic number tells you how many protons there are in a nucleus.
(The atomic number is sometimes called the proton number)
The ‘mass number’ of a nucleus tells you the number of which subatomic particles?
The mass number tells you the total number of protons AND neutrons in the nucleus.
(The mass number is sometimes called the nucleon number)
The ‘proton number’ of a nucleus tells how many ……………. the nucleus contains. Fill in the blank.
‘protons’
The proton number is sometimes called the atomic number
The ‘nucleon number’ of a nucleus tells how many ……………………….. the nucleus contains. Fill in the blank.
protons AND neutrons
The mass number is sometimes called the nucleon number
In Thompson’s ‘plum pudding’ model, what did the dough represent?
- The positive charge of the atom,
* which he thought was very spread out.
In Thompson’s ‘plum pudding’ model, what did the ‘plums’ represent?
The negative electrons,
which he thought were embedded in the dough
Which experiment disproved Thompson’s ‘plum pudding model’?
Rutherford’s alpha particle scattering experiment
Rutherford’s alpha particle scattering experiment led to the discovery of what?
The nucleus of the atom
In Rutherford’s alpha particle scattering experiment, what did he fire the alpha particles at?
Thin gold foil.
Rutherford’s alpha particle scattering experiment had to be conducted in a vacuum. What is a vacuum?
An empty space, where even the air has been removed.
Rutherford’s alpha particle scattering experiment had to be conducted in a vacuum. Why?
Otherwise air molecules would have absorbed the alpha particles.
In Rutherford’s alpha particle scattering experiment, what happened to most of the alpha particles, when they were fired at the gold foil?
The went straight through the foil, undeflected.
In Rutherford’s alpha particle scattering experiment, what happened to a tiny fraction of the alpha particles, when they were fired at the gold foil?
They were deflected through large angles.
In Rutherford’s alpha particle scattering experiment, most of the alpha particles fired at the foil passed straight through, undeflected. What did this show?
That the atom was mostly empty space.
In Rutherford’s alpha particle scattering experiment, a tiny fraction of the alpha particles fired at the foil were deflected through large angles. What did this show?
- the atom had a tiny nucleus
* which contained a concentration of mass and positive charge.
Viewing pollen grains through a microscope, the scientist Robert Brown observed ‘brownian motion.’ Describe his observations.
Brownian motion is:
• the random, zig-zag motion
• of pollen grains in water.
Robert Brown observed that pollen grains in water moved in random, zig-zag paths. How did he explain these observations?
His explanation was that the pollen particles were
• colliding with water molecules
• that were too small to see
State the equation for density.
D = M ÷ V
density can be represented either by the letter D, or by the symbol ρ
State the units in which density is measured.
Density can be measured either in g/cm³
or in kg/m³
The equation for density is
D = M ÷ V
How should this equation be rearranged to find M?
multiply both sides by V, to get:
M = D x V
