Atomic structure Flashcards
define an element
a pure substance consisting of 1 type of atom that cannot be split or broken down into simpler substances by any chemical means
define an atom
the smallest particle of element that can take place in a chemical reaction
what is a postulate
a postulate is a statement that is accepted as true without proof
define atomic number
the number of protons in the nucleus of an atom of an element
what is thermal decomposition
the decomposing of a substance by heat
what is an anode and a cathode
anode- positive electrode
cathode- negative electrode
what does AMU stand for
atomic mass unit
what device is used to measure/compare the mass of different atoms
a mass spectrometer
define isotope
atoms of the same element with the same atomic number but different mass numbers
what is electron configuration
the way in which electrons are arranged around the nucleus
what is the ground state
the lowest energy level [most stable]
what is the excited state of an electron
when an electron absorbs a certain amount of energy and can move to a higher energy level
define orbital
region of space around the nucleus where there is a 90% chance/probability of finding an electron
state Pauli’s exclusion principle
an orbital can have a maximum of 2 paired electrons, which spin in opposite directions
state Hund’s rule
a single electron occupies each orbital before electrons pair
what are nucleons
protons and neutrons collectively
what are valence electrons
the number of electrons that are found in the outer most energy level
what are valency electrons
the number of unpaired electrons (bonding electrons)
what are inert gases
elements that are unreactive and have chemical stability (noble gases)
what is the charge of a proton and neutron
proton- +1
neutron-0
where is the electron found
in fixed orbits
what is the lowest energy level called
the ground state
state the 3 of Daltons postulates
all matter is made up of indivisible indestructible particles called atoms
atoms of a given element are identical
an atom is the smallest particle of an element which can take place in a chemical reaction
the mass of each atom is relative to which element/isotope
carbon-12
