The Atom (C1) Flashcards
What was Dalton’s model of the atom?
A solid sphere that can not be divided into smaller parts. His model did not include protons, neutrons or electrons
What was the plum pudding model?
A cloud of positive charge, with negative electrons embedded in it. Protons and neutrons had yet to be discovered
Describe the steps of the alpha 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 where surprised that some of the alpha particles bounced back and many were deflected (alpha scattering)
What did scientists suggest after the alpha scattering experiment?
The positive charge and mass of an atom must be concentrated in a small space at its centre. They called this space the nucleus.
What was the Nuclear model?
Electrons orbit the nucleus, but not at set distances
Also known as the Bohr model
What was the Electron shell model?
Niels Bohr calculated that electrons must orbit the nucleus at fixed distances. These orbits are called shells or energy levels
What is a proton?
Experiments provided evidence that the nucleus contains smaller particles called protons. They have the opposite charge to an electron
What is a neutron?
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
What is relative atomic mass?
The masses of Protons, neutrons and electrons compared to each other. Protons and neutrons have the same mass and so are given the relative atomic mass of 1. it takes almost 2000 electrons to equal 1 proton so their mass is given as 0
How big is an atom?
1X10 -10
How big in a nucleus?
1X10 -14
How much smaller is the nucleus compared to the atom?
Nuclei are 10 000 times smaller than atoms
What is the Relative charge, Relative mass, and formula for a proton?
RC: +1 RM: 1 Form: = atomic number
What is the Relative charge, Relative mass, and formula for a neutron?
RC: 0 RM:1 Form: = mass number - atomic number
What is the Relative charge, Relative mass, and formula for an electron?
RC: -1 RM:0 Form: = same as the number of protons
What are elements?
Substances made of one type of atom. Each atom of an element will have the same number of protons
What are compounds?
Different types of atom chemically bonded together. The atoms in a compound have different numbers of protons
How many electrons can go in the first shell of an atom? How many on the rest?
Up to two electrons in the first shell, and eight electrons in every shell following
What is an isotope?
Atoms of the same element with different numbers of neutrons, isotopes have
more or less neutrons, changing the mass number
What is a mixture?
Two or more elements or compounds that are not chemically combined together. They can be separated using physical processes
These processes do not use chemical reactions
All 5 of them
How can you separate mixtures? and in what situation?
Filtration - insoluble solids and a liquid
Crystallisation - soluble solid from a solution
Simple distillation - solvent from a solution
Fractional distillation - two liquids with similar boiling points
Paper chromatography - identify substances from a mixture in a solution
What does abundance mean?
the percentage of atoms with a certain mass
What are shells?
Orbits of electrons around an atom
Give the order of the different models of the atom
Dalton’s model, The plum pudding model, Nuclear model, Bohr (electron shell) model
