Atomic Structure and the Periodic table Flashcards
All materials are made of tiny particles called…
Atoms
A material made of only one type of atom is called an…
Element
A substance which contains two or more types of atoms chemically bonded together is a…
Compound
A substance which has two or more types of atoms which are NOT bonded together is a…
Mixture
The smallest unit of a compound is a…
Molecule
How many natural occurring atoms are there?
About 100
What are the state symbols and what do they mean ?
(s) . = solid
(l) = liquid
(g) = gas
(aq) = aqueous/dissolved in water
What did Democritus discover?
Greek Philosopher
Hypothesized that atoms can’t be destroyed, differ in size, shape and temperature,are always moving and are invisible.
What did John Dalton discover?
Introduced compounds - when 2 different elements combine.
When different elements join, separate or rearrange, chemical reactions then take place.
What did JJ Thomson discover?
Discovered the electron.
Tiny Negatively charged particle with a mass about 2000 times smaller than the lightest atom.
Carried out experiments proving atoms could split.
Plum pudding model:
The atom was mainly positive and negative electrons wandered around the atom.
What did Rutherford discover?
Gold foil experiment proved Thomson was wrong.
Electrons are orbiting around a nucleus which contains very dense positively charged protons.
All materials are made of tiny particles called…
Atoms
What did Neils Bohr discover?
Electrons must orbit around the nucleus at set distances in certain fired energy levels (shells) .
What did James Chadwick discover?
The neutron.
It is the Neutral part - no charge.
Same mass as a proton.
