C1 Particles Flashcards
What is the radius of an atom?
1 × 10-10
What is the radius of a nucleus?
1 × 10-15
What is the structure of solids?
-Strong forces of attraction between particles hold them close together in fixed positions in a very regular lattice arrangement.
-Particles don’t move from their positions so the shape and volume doesn’t change.
-Particles vibrate in their fixed positions so when a solid is heated, they vibrate more and the solid slightly expands.
What is the structure of liquids?
-Some forces of attraction between particles so they are close together but randomly arranged as they are free to move past each other (they tend to stick together).
-No definite shape as they flow to fill the container however they keep the same volume.
-Liquids expand slightly when heated as there’s more kinetic energy.
What is the structure of gases?
-No forces of attraction between particles as they are spread apart and randomly arranged.
-Particles are free to move, travel in straight lines and only interact when they collide.
-No definite shape or volume and will always fill any container.
-When heated, they either expand or their pressure increases.
Where is most of the atom’s mass?
Most of the atom’s mass is in the nucleus as it contains subatomic particles which are heavier than electrons.
What is the relative charge and relative mass of protons?
-Relative charge: +1
-Relative mass: 1
What is the relative charge and relative mass of neutrons?
-Relative charge: 0
-Relative mass: 1
What is the relative charge and relative mass of electrons?
-Relative charge: -1
-Relative mass: 0.0005
What is the period number in the periodic table?
Number of electron shells.
What is the mass number in the periodic table?
Sum of neutrons and protons.
What is the group number in the periodic table?
Number of electrons in outer shell.
What is the atomic number in the periodic table?
Proton number and sometimes electron number if not an ion.
What is the atom?
Has a positively charged nucleus orbitted by negatively charged electrons.
What are physical changes?
They are reversible and require energy as well as a change in state.
What are chemical changes?
They are irreversible and require a chemical reaction so what you produce is chemically different to what you react.
What are molecules?
Made up of 2 or more atoms from the same or different elements.
What are isotopes?
Elements with the same atomic numbers but different mass numbers.
What are ions?
-Form when an atom gains / loses electrons.
-Cations: positive metal ions.
-Anions: negative non-metal ions.
What is the Billiard Ball model?
-Discovered by Dalton in 1803.
-Different elements have different atoms.
-Atoms of the same element are identical.
-Atoms can’t be divided.
-Atoms can join to make new substances.
-Atoms make up all substances.
What is the Plum Pudding model?
-Discovered by JJ Thompson in 1897.
-The atom is a weak, positively charged sphere embedded with negative electrons.
How was the plum pudding model discovered?
-JJ Thompson used a cathode-ray tube to conduct an experiment with showed that there are small particles inside atoms.
-This disproved Dalton’s theory about atoms not splitting.
What is the planetary model?
-Discovered by Rutherford in 1911.
-The atom has a small, central nucleus of concentrated positive charge.
-Electrons orbitted around the nucleus.
-He also discovered protons.
How was the planetary model discovered?
-Rutherford and his 2 students, Geiger and Marsden, fired positive alpha particles at thin gold foil.
-They were supposed to go straight through however some particles deflected or rebounded back.
What is Bohr’s Model?
-Discovered in 1913.
-Electrons orbitted around the nucleus in fixed shells.
-This prevents the atom from collapsing due to electrons being attracted to the nucleus if there were no shells.
Who discovered neutrons?
Chadwick discovered neutrons in 1932.
What are the limitations of the particle model that it doesn’t take into account?
-The forces of attraction between particles (amount of energy needed to change state as well as the melting and boiling point depend on the strength of these forces).
-The size of particles and the space between particles (nature of particles depends on the structure of the substance and the type of bonding involved).
