C1 Flashcards
What is the force between the particles in a solid?
A strong force, holding them in fixed positions and a regular lattice arrangement
Why do all solids keep a definite shape and volume?
The particles don’t move from their fixed positions
What are particles in a solid constantly doing, and what happens if you heat a solid?
They are constantly vibrating about their positions - the hotter a solid becomes, the more it vibrates
What happens when a solid is heated/vibrates more?
It expands slightly
What is the force between the particles in a liquid?
There is some force of attraction between the particles, allowing them to freely move past each other but they do tend to stick together
How do liquids behave in a container?
They don’t keep a definite shape and so flow to fill the bottom of their container. However, they keep the same volume.
What is the force between the particles in a gas?
There is no force of attraction between the particles, meaning that they are free to move. They travel in straight lines and only interact when they collide.
How do gases behave in a container?
They don’t keep a definite shape or volume and will always fill any container.
What do gas particles do when they bounce off of the walls of their container?
They exert pressure
What happens when a gas is heated?
The particles, which are moving constantly, move faster. They either expand when heated, or their pressure increases.
What are the issues with the “particle theory” model?
The model doesn’t show forces between particles.
What is a physical change?
When a substance changes from one state of matter to another. No new substances are made - the original chemicals just change state.
What is a chemical change?
Bonds between atoms break and atoms change places - the atoms from the substances you start off with (reactants) rearrange themselves to form different chemicals (products).
How did John Dalton describe atoms?
He described them as solid spheres and said that different spheres made different elements.
What did JJ Thomson’s experiments and measurements show him?
His measurements of charge and mass showed that an atom contained small, negatively charged particles - electrons.
What was JJ Thomson’s model known as?
The Plum Pudding Model
What experiment did Ernest Rutherford, Hans Geiger and Ernest Marsden conduct?
The gold foil experiment - they fired positively charged alpha particles at an extremely thin sheet of gold
What did Rutherford expect from his experiment?
He assumed that the particles would pass straight through, or slightly deflected at most.
What actually happened in the gold foil experiment?
Most of the particles went straight throw the sheet, but some were deflected (more than expected), and a small number were deflected backwards. This showed that the plum pudding model couldn’t be right.
What theory did Rutherford create as a result of his work?
The theory of the nuclear atom. He said that there was a tiny, positively charged nucleus at the centre, surrounded by a “cloud” of negative electrons.
What did Niels Bohr propose?
He suggested that the electrons in an atom were contained in shells.
What is the relative mass and charge of a proton?
Charge: +1
What is the relative mass and charge of a neutron?
Charge: 0
What is the relative mass and charge of an electron?
Charge: -1
What is the radius of an atom?
10^-10 metres
What is a molecule?
Something that is made up of two or more atoms. They can be made of the same element, or different elements.
What is the mass number and atomic number?
Atomic number: number of protons
When do ions form?
When atoms (or groups of atoms) gain or lose electrons
What is an isotope?
Different forms of the same element, which have the same number of protons but a different number of neutrons.
What does the atomic number of an atom decide?
The element
