The Periodic Table Flashcards
Who is known as the father of chemistry?
Robert Boyle
(He defined a element)
What is an element
A substance that cannot be broken down into anything simpler by chemical means
What did Humphrey Davy do
Discovered many elements by passing electricity through compounds to split them into their element
Who proposed the idea of Triads
Johann Dobereiner
What is a Triad
A group of three element with similar chemical properties where the mass of the middle element element is equal to the average of the other two
Name two examples of Triads
Li, Na, K
Cl, Br, I
Who tried arranging the element into octaves?
John Newlands
What is Newlands Law of octaves
When the elements were arranged in order of atomic mass. Every eight element had similar chemical properties
Problems of Newlands Law of Octaves
He tired to force all known elements into the pattern.
Silver was included in the Alkali metals. Silver is unreactive
He didn’t know that some elements hadn’t be discovered yet (Noble gasses)
Who arranged the elements according to atomic weight?
Mendeleev
Key aspects of Mendeleev’s periodic table
Elements were grouped by similar properties.
Elements were grouped in increasing atomic weight
What Mendeleev did differently
Left gaps in his table for undiscovered elements
Reversed the other of some elements ( more important to have elements with similar properties grouped together)
What is Mendeleev’s Periodic law
When elements are arranged in order of increasing atomic mass and elements with similar chemical properties are placed beneath each other, chemical properties repeat at regular intervals
How was Mendeleev able to predict the properties of elements like gallium and germanium before they were discovered?
Because elements in the same group have similar properties, Mendeleev realised the undiscovered element would have similar properties to the other elements already in that group
What is the atomic number
The number of protons in the nucleus of an atom
The Mass number
The number of protons and neutrons in the nucleus of a atom
Who discovered how to calculate the number of protons
Henry Moseley
What did Henry Mosley discover
He discovered how to calculate the number of protons.
Each element has a unique atomic number
What is the Morden periodic law
When elements are arranged in a order of increasing atomic number, the properties of the element reoccur periodically
Differences between the Modern periodic table and Mendeleev’a periodic table
Modern
Arranged in increasing atomic number
No gaps
Transition metals have a different block
Nobel gasses included
Mendeleev’s
Arranged in order of increasing weight
Gaps left for undiscovered element
No transition metal block
No Nobel gasses
What are Isotopes
Atoms of the same element which have different mass numbers due to the different number of neutrons in the atom
What is Relative atomic mass
The average of the mass numbers of the Isotopes of the elements as they
Occur naturally.
Taking into account their abundances and expressed on a scale which the atoms of Carbon-12 isotope have exactly 12 units
Molecule
Two or more atoms chemically combined
Name the functions of a mass spectrometer
Identify the presence of isotopes and their abundances
To measure Relative atomic masses and relative molecular masses
Identify unknown compounds such as drugs
Measure the relative abundance of isotopes
How do you get RMM
Add together the atomic masses of the atoms in a molecule
What is the principle of mass spectrometer?
Positive ions separate based of their relative masses when moving in a magnetic field. The lighter the relative mass of the charged particle, the greater the radius of the circular path along which they are deflected
Name the 5 processes that occur in mass spectrometry?
Vaporisation
Iodisation
Acceleration
Separation
Detection
Describe Vaporisation
A small amount of the sample is injected. As there is a vacuum, liquids turn to gasses
Describe Ionisation
Aroms of the vapourised elemet pass into an ionisation chamber and are converted into ions
Describe acceleration
The positive ions produced passes into an electric feild and are accelerated towards a magnetic feils
Describe separation
Ions are deflected as it passes through a magnetic field depending on atomic mass.Lighter ions are deflected more than heavier ions. This way they can be separated and identified.
Describe Detection
The positive ions hit the detector at the end of the mass spectrometer. Their abundances and mass are recorded on a computer
How do you calculate Ar?
(%no. x mass no.) + (%no. x mass no.) / 100
