C1 Flashcards
What is an atom
The smallest particle of an element - they contain a positive nucleus made of protons and neutrons which is orbited by electrons
1×10^10m
What is an element
Substance whose atoms have the same atomic number
What is a particle
A tiny piece of matter such as an atom ion or molecule
What is a molecule
A particle consisting of two or more non-metals which are covalently bonded
What is a proton
A positive particle with a relative mass of 1 and a relative charge of + 1
What is a neutron
A neutral particle with a relative mass of 1 and a relative charge of 0
What is an electron
A negative particle with a relative mass of 0.0005 and a relative charge of -1
What is a chemical symbol
A letter / letters used to represent an element
What is an elementd atomic number
The number of protons in the nucleus of an atom
(Which is equal to the number of electrons)
What is an elements mass number
Number of protons and neutrons in an atoms nucleus
What are isotopes
An atom with a different number of neutrons to its traditional element
What is an ion
A charged particle formed when atoms gain or lose electrons
Which number is always higher the mass number or atomic number
The mass number as it counts both neutrons and protons
What did Democritus and Lecuppis believe
If you could not cut something any futher you where left with an atom - they were indivisible and could not be seen
What was John Daltons model of the atom
A tiny solid ball where all atoms in an element are the same and different elements contain their own atoms
What was JJ Thomsons model of the atom
He believed an atom was made of negative electrons floating in a positive mass.
He used the plum pudding model to show that the plums (electrons) where embedded in a pudding (positive mass)
He believed the mass may be solid or a cloud
What was Ernest Rutherfords model / what did he do
He fired alpha particles at a piece of gold foil
He expected the alpha particles to go through the foil but some came back
To explain this he said that atoms were made of a positive nucleus with negative electrons orbiting it
What did Niels Bohr do?
With Thomsons model you would expect the electrons to spiral until they hit the nucleus so Bohr said that:
Electrons can only move in fixed shells - electron shells - around the nucleus
What did James Chadwick discover
Neutrons
What is a chemical change
A reaction that makes a new substance and is difficult to change
What is a physical change
A reversible change where no new substances are made
This change can easily be observed
What are the limitations of using the particle model
It doesn’t show
Forces between the particles
The size of particles
The space between the particles
What is the particle model
A model showing the states - solid liquid and gas
Particles are represented as hard spheres
How are particles held together
Through electrostatic bonds of attraction
