The Periodic Table Flashcards
What is an element (Boyle)
A substance that cannot be broken down into simpler substances by chemical means
What elements were there according to the Greeks
Earth
Wind
Fire
Water
What did Davy discover
Discovered Na , K , Ca , Ba etc. (elements )
Isolated them by electrolysis
How did Dobereiner arrange the periodic table
In triads
Only worked for a few elements coincidentally
What are triads
A group of three elements with similar chemical properties in which the atomic weight of the middle element is approx. equal to the average of the other two
How did Newlands arrange the periodic table
Octaves
Order of Atomic weight , didn’t leave gaps for new elements to be discovered
Noble gases weren’t discovered - doesn’t work with them involved
What are Newlands Octaves
Arrangements of elements in which the first and eighth element have similar properties
What are isotopes
Isotopes are atoms of the same element which have different mass numbers due to the different number of neutrons in the nucleus
What is the Relative atomic mass of an element
The average mass of an atom of the element relative to one-twelfth of an atom of carbon-12
What is the stages in the mass spectrometer
- Vaporisation
- Ionisation
- Acceleration
- Separation
- Detection
Uses of the mass spectrometer
Identify presence of isotopes
Measure relative abundance of isotopes
Identify unknown compounds
- analysis of gases from waste dump
What happens in the vaporisation stage in the mass spec.
the substance is vaporised by heat and reduced pressure
What happens in the ionisation stage in the mass spec.
the sample is ionised by bombarding it with high energy electrons producing +ive ions
What happens in the acceleration stage of the mass spec.
ions are accelerated by negatively charged plates
What happens in the separation stage of the mass spec.
ions are deflected by magnetic fields
