Chemistry Revision Flashcards
What is the atomic number
The number of protons
What is the mass number
The number of protons plus the number of neutrons
What is the relative atomic mass
The mean mass of all the possible isotopes of an atom, and is a relative measure of how heavy this mean atom is compared to 1/12 mass of one atom of carbon-12
What are atoms made of
A positive nucleus containing protons and neutrons with negative electrons in shells far away
What is an isotope
A different form of of the same element, with the same proton and electron number, but different neutron number
What is an ion
An atom which is charged - negative if more electrons and positive if fewer
What did Dalton think
Atoms were tiny spheres with hard centers
What did Thompson think
Atoms were like plum puddings with positive matter surrounded randomly with negative electrons
What did Rutherford think
Thought atoms were mostly space with positive nuclei orbited by electrons in shells
What is group number
the same as the number of electrons in the outer shell
What is period number
The amount of shells
Electrons are…
Negatively charged and are attracted to the positive nucleus as well as repel other electrons
what format do electrons fill the outer shell by
2.8.8.2
Most elements are…
Metals and are definitely found in groups 1, 2 and 3
Atoms in group 1 form
+1 ions
