The Periodic Table CH4 Flashcards
What Irish chemist defined the element?
Robert Boyle
What is a element?
A substance that can’t be split into a simper substance by chemical means
What did Humphrey Davy do?
Humphrey Davy discovered many elements by passing electricity through compounds
What is a triad?
a group of three elements with similar chemical properties in which the middle element is the average atomic weight of the other two.
what did John Newlands do?
Arranged elements by their atomic weights.
Law of octaves
Newlands octaves are arrangements of elements in which the first and eighth elements have similar properties.
Issues with Newlands Octaves?
Some elements had not been discovered yet, he should have left gaps for them and noble gases.
Mendeleev’s Periodic Table
Arranged elements in order of increasing atomic weight and placed elements with similar properties under each group.
Mendeleev’s Law
When elements are arranged in order of increasing atomic weight, the properties of the elements recur periodically.
Why did he reverse some elements?
He reversed the order of some elements, he placed more importance on properties rather than atomic weight. ( tellurium and iodine)
Who discovered the number of protons in a nucleus. Atomic number?
Mosley
What did Mosey show?
Elements should be arranged by atomic number not atomic mass.
Modern periodic law
When elements are arranged in order of increasing atomic number, the properties of the element recur periodically
Atomic Numbers
The number of an element in the periodic table tells us the number of protons in the nucleus.
Mass Numbers
The mass numbers of an element is the sum of the number of protons and the number of neutrons of the atom of that element.
Isotopes
Atoms of the same element which have different mass numbers due to different numbers of neutrons in the nucleus.
What is a mass spectrometer?
a instrument used to detect the masses of an atom.
Relative atomic mass
The average mass numbers of the isotopes of the element taking their abundances into account and expressed on a scale in which the atoms of the carbon12 isotope have a mass of exactly 12
Principle of mass spectrometry
Charged particles in a magnetic field are deflected to different extents according to their masses and thus separated according to these masses
Mass spectrometry uses?
identifying unknown substances, drug testing. Forensic science and space travel studying.
Electron configuration
Shows the arrangement of electrons in an atom.
Aufbau principle
When building up electrons configuration of an atom in its ground state, the electrons occupy the lowest available level.
Hund’s rule of maximum multiplicity
States that when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs.
Pauli Exclusion Principle
States that no more then two electrons may occupy an orbital and they must have opposite spin.
