Elements, atomic structure, compounds and mixtures Flashcards
Who first theorised all matter was made up of invisible particles called atomas?
Democritus, 460BC
Cutting cheese
Who theorised atoms of each element are different like tiny snooker balls!
Dalton, 1808AD
Who created the plum pudding model?
J.J. Thompson,
1897AD
What is the plum pudding model
An atom contained negative electrons and ‘positive stuff’ scattered throughout
What did Rutherford discover and how?
By firing alpha particles at gold foil, he realised some bounced back meaning there were very small pockets of positive energy which he called nucleus
When did Rutherford discover the nucleus?
1911
What did Bohr discover (1913)
Electrons found in shells
What did Chadwick discover
In 1932 he discovered a neutron. Otherwise particles in the nucleus would repel and fly apart
Element definition
Cannot be broken down into anything simpler
Arrangement of atoms in an element
Made up of only one type of atom
Compounds definition
Two or more elements chemically bonded in a fixed ratio
How to separate a compound
Must undergo a chemical change
Mixture definition
Two or more elements or compounds in a variable ratio not chemically bonded
Number of protons=?
Atomic number
Number of neutrons =?
Mass number - atomic number
