C1.1-2 & C1.5-8 Flashcards
What is an element ?
Substances made up of only one type of atom
What is a molecule
A particle that consists of two or more atoms chemically bonded together
What are reactants ?
The substances you start with
What are products
The new substances made in a reaction
The law of conservation of mass
The total mass of the products formed in a reaction is equal to the total mass of the reactants.
What were John Dalton’s ideas
He thought all matter was made of tiny particles called atoms, which he imagined as tiny speres that could not be divided and that each chemical element had its own atoms
J J Thomson model and description
He discovered electrons through an experiment . He then made the plum pudding model which is a cloud of posative charge with negative electrons embeded in it
Aplha scattering experiment
- Scientists fired small, positively charged particles (called alpha particles) at a piece of gold foil only a few atoms thick.
- They expected the alpha particles to travel
straight through the gold. - They were surprised that some of the alpha
particles bounced back and many were deflected (alpha scattering). - To explain why the alpha particles were repelled the scientists suggested that the positive charge and mass of an atom must be concentrated in a small space at its centre. They called this space the nucleus.
Nuclear model
Scientists replaced the plum pudding model with the nuclear model and suggested that the electrons oribut the nucleus, but not at set distances
What is the Niels Bohr model
Electron shell (Bohr) model, Niels calculated that electrons must orbit the nucleus at fixed distances. These orbits are called shells or energy levels
Earnest Rutherford model (ASE)
The mass of an atom is concentrated at its centre, the nucleus. The nucleus is posativley charged
What did James Chadwick discover
James Chadwick carried out experiments that gave evidence for a particle with no charge. Scientists called this the neutron and concluded that the protons and neutrons are in the nucleus, and the electrons orbit the nucleus in shells.
Whats the atomic number
The number of protons in an element
What is the mass number
The number of protons plus neutrons in the nucleus of an atom
What is an ion
An ion is a charged atom
