Atomic Structure Flashcards
Define an atom
Smallest particle of an chemical element that can exist.
Define atomic number (Z)
The number of protons in the nucleus of an atom.
Define mass number (A)
The total number of protons and neutrons in a nucleus.
Define Relative Atomic Mass (Ar) using the C12 scale
It is the average of the mass numbers of isotopes of the element, as they occur naturally taking their abundances into account, relative to 1/12th mass carbon 12 atom.
Define an isotope
Atoms of the same element with the same number of protons but different number of neutrons.
What is the law of conservation of mass?
The law of conservation of mass is that matter cannot be created or destroyed. It can change forms but is conserved.
What particles make up everything?
Atoms, Ions and Molecules
Can atoms be created or destroyed?
Atoms cannot be created or destroyed.
What do the Greeks contribute to chemistry?
They said that all matter is made up of very small particles.
What did Dalton contribute to chemistry?
He said that atoms are indivisible and cannot be broken down any further.
What are cathode rays?
Streams of negatively charged particles called electrons which travel in straight lines.
What did Crooks Do?
He passed an electric current through an electric tube.
What did Crooks discover?
He noticed that there was radiation was coming from the negative electrode.
What did Crooks call the radiation?
He called the rays of radiation cathode rays.
What did Stoney contribute to chemistry?
He suggested naming the particles found in cathode rays ‘electrons’.