Atomic Theory and Structure Flashcards
Smallest Unit of Ordinary matter
which dictates the properties of element
Atoms
greek work atoms
“atomos” - Indivisible
expressed the belief that all matter consists of very small, indivisible particles.
Democritus
Three fundamental particles of an atom
Electron
Proton
Neutron
stream of negatively charged particles
Electrons
positively charged particles
defines the element
Protons
Uncharged dense particle
Neutrons
contains protons and neutrons. Mass of the atom
Nucleus
correspond to the number of protons in the nucleus of an element
Atomic Number
Formulated a precise definition of the indivisible building blocks of matter that we call atoms.
atom as the basic unit of an element that can enter into chemical combination.
John Dalton
Postulates of Daltons Atomic Theory
All matter consists of atoms.
Atoms of one element cannot be converted into atoms of another element.
Atoms of an element are identical in mass and other properties and are different from atoms of any other element.
Compounds result from the chemical combination of a specific ratio of atoms of different elements.
What was J.J. Thomson’s most significant discovery?
Electrons (1886)
Oil-drop experiment
These experiments allowed him to determine the magnitude of the electron charge.
Robert Milikan
How did Thomson discover the electron?
Through experiments with a cathode ray tube, observing that the beam of particles was deflected by electric and magnetic fields.
A model where the atom is a sphere of positive charge with negatively charged electrons embedded within it.
Plum pudding model
How did Thomson’s work contribute to the understanding of atomic structure?
It showed that atoms are divisible and contain smaller subatomic particles, leading to the development of more accurate atomic models
What experiment did Rutherford use to discover the nucleu
Rutherford directed alpha particles at a thin sheet of metal foil, observing deflections to discover the nucleus.
What did Rutherford conclude from the large deflections of alpha particles?
The large deflections indicated a concentrated positive charge in the atom’s center, which he identified as the nucleus.
What did Rutherford expect to happen with the alpha particles in his experiment?
He expected them to pass through the foil with minimal deflections.
atoms of an element with the same number of protons, but a different number of neutrons
Isotope
contains charge. Either positive or negative charge.
Ion
a type of ion that contains positive charge. It tends to lose electron. The magnitude of the charge is the number of electron that can be lost by an ion.
polyatomic
Cation
a type of ion that contains negative charge. It tends to gain electron. The magnitude of the negative charge is the number of electron that can be gained by an ion
monoatomic
Anion
Strictly defined as a combination of two or more atoms
Molecules
Compound vs Molecule
All compound are molecule but not all molecule are compounds
