🔬 Particles Flashcards
(12 cards)
What is the size of the radius of an atom? (in metres)
and
What is the size of the radius of an atoms nucleus? (in metres)
10 to the power of -10
10 to the power of -14
What is the size of one nanometre? (in metres)
1 x 10 to the power of -9
How does particle theory describe solids, liquids, and gases?
Solids: tightly packed, fixed positions, vibrate.
Liquids: close together, move past each other.
Gases: far apart, move freely and quickly.
What are the weaknesses of the particle model?
It doesn’t show forces, assumes particles are solid spheres, and ignores variation in particle size.
How has the model of the atom changed over time?
Dalton →
Thomson (electrons and plum pudding) →
Rutherford (positive nucleus and atom mostly empty mass) →
Bohr (electron shells at fixed energy levels orbit) →
Chadwick (neutrons).
What did Rutherford’s gold foil experiment show?
Atoms are mostly empty space with a small, dense, positively charged nucleus.
How do you calculate protons, neutrons, and electrons?
Protons = atomic number.
Neutrons = mass – atomic number.
Electrons = same as protons (adjust for charge in ions).
What are the charges and masses of subatomic particles?
Proton: +1, mass 1.
Neutron: 0, mass 1.
Electron: –1, 0.0005.
Why do isotopes have the same chemical properties?
They have the same number of electrons, which determine chemical reactions.
Why are nanoparticles useful in science?
Very high surface area to volume ratio makes them useful in catalysts, drug delivery, and sunscreens.
How do filtration and crystallisation separate mixtures?
Filtration separates solids from liquids. Crystallisation forms solid crystals from a solution by evaporating the solvent.
What is the difference between physical and chemical changes?
Physical changes are reversible and don’t form new substances.
Chemical changes form new substances and are often irreversible.
