Question | Answer |
First scientist to use the word "element" | Robert Boyle |
Element | A substance that cannot be broken into simpler parts by chemical means |
Who developed a theory on triads | Dobereiner |
2 properties of a triad: | 1:3 elements with similar properties
2:The atomic weight of the middle element was equal to the average of all 3 |
Examples of triads | Chlorine, Bromine, Iodine
Calcium, Strontium, Barium |
Developed a Law of Octaves | John Newlands |
Octaves | When elements are arranged in increasing atomic weight the first and eight element have similar properties |
Creator of the Periodic Table | Dmitri Mendeleev |
Law of Periodicity | When elements are arranged in order of increasing atomic weight the properties of the elements vary periodically. |
Why did Mendeleev reverse the order of Iodine and Tellurium | To make sure they were in groups with similar properties |
Discovered a way to determine the number of protons in a nucleus | Henry Mosely |
Atomic Number | The number of protons in the nucleus of that element |
3 differences between Mendeleevs and the current Periodic Table | 1: Mendeleev used atomic weight, we use atomic number
2: Mendeleev had 63 we have 109 elements
3: There are no gaps in the modern Periodic Table
4: The transition metals are in a separate group in the modern table |
3 uses of the Periodic Table | Getting atomic numbers and mass numbers
Getting relative atomic masses
Calculating and writing electronic configuration |
Mass number | The sum of the number of protons and neutrons in that element |
Isotope | An atom of the same element with a different mass number due to a different number of neutrons in the nucleus |
2 isotopes of Hydrogen | Deuterium and Tritium |
Developed the mass spectrometer | William Aston |
Functions of a mass spectrometer | Used to detect the presence of isotopes of an elements and the percentages of each of these isotopes.
Used to calculate the relative atomic mass of an atom |
5 stages of the mass spectrometer | Vaporisation, Ionisation, Acceleration, Separation, Detection |
Use of mass spectrometer in sports | used to detect banned substances in athletes blood |
Aufbau Principle | The aufbau principle states that when building up the electronic configuration of an atom in its ground state, the electrons occupy the lowest available energy level |
Hunds rule of maximum multiplicity | This states that when two or more orbitals of equal energy are available, the electrons occupy them singly first before filling them in pairs. |
Pauli Exclusion Principle | This states that no more than 2 electrons may occupy an orbital and this may only do if they have opposite spin. |
How many electrons can an s sublevel hold | 2 |
How many orbitals can the entire p sublevel hold | 6 |
How many electrons can the entire d sublevel hold | 10 |
How many orbitals can the entire f orbital hold | 18 |