The Periodic Table Flashcards
What four elements did Greek philosophers think were part of what the world was made up of
Fire, earth, water, air
What’s Roberts Boyles contribution to the Periodic table?
Defined an element
Defined compounds
What is an element
A substance that cannot be broken into simpler substances by chemical means
What was Humphry Davy’s contribution to the periodic table?
Discovered potassium by passing electricity through a compound of potassium, which showed elements cold be extracted from their compounds using electricity.
Also discovered sodium, calcium, barium, strontium and magnesium the same way
What are Dobereiner’s Triads?
A triad is a group of three elements with similar chemical properties, where the atomic weight of the middle element is equal to the average of the other two.
Name examples of triads
Chlorine Bromine Iodine
Calcium Strontium Barium
Lithium Sodium Potassium
What is are Newlands’ Octaves
They are arrangements of elements in which the first and the eight element, counting from a particular element, have similar properties
What were some problems with Newlands’ Octaves?
Some elements weren’t discovered yet, Newland should have left gaps
Noble gases weren’t discovered yet
What is Mendeleev’s Periodic Law
When elements are arranged in order of increasing atomic weight, the properties of the element recur periodically
Summarise Mendeleev’s work
Placed elements with similar properties in the same vertical column to demonstrate the regular repetition of properties.
Left gaps in Table, to make all known elements fit into the proper group.
Predicted the properties of undiscovered elements, since he knew the properties of the other elements in that group
Reversed the order of some elements to make them fall into groups of elements with similar chemical properties
What is an atomic number
Number of protons in nucleus of atom
Moseley’s contribution to Mendeleev’s table
Used X-rays to find atomic number of an element
Showed if elements are arranged in order of increasing atomic number it is not necessary to reverse them
Moseley’s X-ray study proved Mendeleev right for putting tellurium above iodine, despite the higher atomic weight of tellurium
Showed that by arranging them in order of increasing atomic number the elements fall into the correct groups naturally
What is the Modern Periodic Law
When Elements are arranged in order of increasing atomic number, the properties of the element recur periodically
What are the differences between Mendeleev’s Periodic table and the Modern one?
Mendeleev’s is arranged in order of atomic weight while the modern periodic table is order of increasing atomic number
More elements in modern periodic table, cause some elements were not discovered like noble gases
No gaps in Modern Periodic Table
Transition elements are listed in a separate block in the middle of the table in the Modern Periodic table
What is mass number
The sum of number of protons and neutrons in nucleus of element
What is an Isotope
Atoms of the same element that have different mass numbers due to different numbers of neutrons in nucleus
What is Relative Atomic Mass
The mass of the isotopes of an element, as the occur naturally, taking into account their abundance’s relative to mass 1/12 carbon 12 atom.
What are the five processes involved in a mass spectrometer
Vaporisation: Turns liquid injected into gas
Ionisation: Turn atoms or molecules to ions using electron gun
Acceleration: Accelerate positive ions to high speeds
Separation in a magnetic field: Ions separated according to mass
Detection: Ions fall on detector, very sensitive instrument that responds to ions hitting it
What is the principle of mass spectrometry?
Charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to these masses
What are the uses of the mass spectrometer
Identify the presence of isotopes
Measure the relative abundances of isotopes
Measure relative atomic masses and relative molecular masses
Identify unknown compounds
What is electron configuration
It shows the arrangement of electrons in an atom of an element
(ignore)What is Aufbau Principle
When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels
(ignore)What is Pauli Exclusion Principle
No more than two electrons may occupy an orbital and they must have opposite spin
(ignore)What is Hands Rule of Maximum Multiplicity
When two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs
