C1 Particles Flashcards
Name three examples of particles in chemistry
Atoms, ions, molecules, compounds
Describe the main difference between the arrangement of particles in the liquid state and particles in the gas state
Liquid:
Particles move around each other
Medium forces of attraction
Fixed volume
Gas:
Particles move freely
No forces of attraction
No fixed volume
No fixed shape
Explain why you can compress a substance in the gas state
Since gas has no fixed volume, it can move freely and so will move into space
Explain why a solid expands when it is heated
When a solid is heated, its forces of attraction begin to break down and it is able to move slightly, so the particles move away from each other
What is a physical change?
A change of state that can (generally) easily be reversed. The arrangement and number of particles and atoms are not changed. No new products are made
What is a chemical change?
A change that produces one or more new substances. Different particles react with each other to form different products. They are usually hard to reverse.
What are the advantages of the particle model?
It shows the arrangement of the atoms in all three states of matter
What are the disadvantages of the particle model?
The distance between the particles (in the gas state)
It does not show the forces/movement of particles
It is 2D when particles are 3D
What keeps particles close together in liquids?
Electrostatic forces of attraction
What is the charge and mass of a proton?
+1, 1
What is the charge and mass of an electron?
-1, 0.0005
What is the charge and mass of a neutron?
0,1
Why is most of an atom’s mass in its nucleus?
The nucleus is where the protons and neutrons are, which weigh far more than the electrons orbiting it.
How many times bigger is the radius of an atom compared to the radius of its radius?
100,000 times
Describe the structure of an atom
A nucleus of protons and neutrons orbited by electrons in fixed electron shells.
How many times greater is the mass of a proton compared to an electron?
2000 times
What is an isotope?
Atoms of an element with the same number of protons and electrons but different numbers of neutrons
Define atomic number
The number of protons in an element (and the number of electrons because they are the same)
Define mass number
The total number of protons and neutrons in an atom
Define ion
Ions are charged particles formed when atoms, or groups of atoms, lose or gain electrons during chemical reactions
What was John Dalton’s theory about the atom?
Atoms were solid spheres with nothing in them
What was the plum pudding model and who invented it?
The plum pudding model described an atom that was a large positive mass with electrons embedded within it like a pudding cake with plums in it. It was invented by J.J. Thomson
What was Rutherford’s experiment?
Rutherford fired positively charged alpha particles at a thin sheet of gold foil (atoms).
What was the expected result of Rutherford’s experiment?
Rutherford expected all the particles to pass straight through as there was not enough strong positive charge to deflect any of them.
