Unit 1: Topic 1 - Atomic Structure Flashcards
In the early 1800’s what did Dalton state?
1) All elements are made up of small invisible particles called atoms.
2) Atoms cannot be created or destroyed.
3) Atoms of different elements have different properties.
4) When atoms combine they form molecules and compounds.
In 1897 J.J. Thompson said his model looked like?
A plum pudding.
J.J. Thompson stated that?
The negative electrons were embedded in a positive sphere.
In 1911, Ernst Rutherford said?
The electrons orbit around a positive nucleus.
In 1932, what did James Chadwick discover?
The neutron. ( this lead to todays model of the atom )
An atom is composed of?
Small, dense, positively charged nucleus, which at the centre is composed of protons and neutrons with negatively charged electrons in shells orbiting around the nucleus.
What is the PROTONS relative mass, relative charge? Where is it positioned?
Relative Mass = 1
Relative Charge = +1
Positioned = Nucleus
What is the NEUTRONS relative mass, relative charge? Where is it positioned?
Relative Mass = 1
Relative Charge = 0
Positioned = Nucleus
What is the ELECTRONS relative mass, relative charge? Where is it positioned?
Relative Mass = 1/1840
Relative Charge = -1
Positioned = Shell
Atomic number means?
This is the NUMBER OF PROTONS AND ELECTORNS in an atom.
Mass number means?
This is the TOTAL NUMBER OF PROTONS AND NEUTRONS in an atom.
Element means?
Is a substance that consists of only one type of atom and it cannot be broken down into anything simpler by chemical means.
How many electrons can go in each shell of an atom?
Shell number 1 - 2 electrons
Shell number 2 - 8 electeons
Shell number 3+ - 8 electeons
Atoms with electric charge are called?
Ions
Atoms with positive charges are called?
Cations
