Structure of an Atom and the Periodic Table Flashcards
first person to actually describe the atoms is?
Democritus
theory based on the law of conservation and of definite proportions
John Dalton’s atomic theory
law of conservation of mass is
founded
antoine lavoiser
father of
modern chemistry
antoine lavoiser
Law of definite proportions was postulated by
joseph proust
theory
if a compound is broken down into its
constituent element. The masses of the
constituent will always have the same
proportion regardless the quantity of
other substances.
law of proportion
will always have a
definite proportion whether we change
the quantity or now. However, if we
change the type of molecule to
another, there will be a different
proportion
John Dalton’s Atomic Theory
EXCEPT:
* All matter consists of tiny particles called atoms
* An atom cannot be created, divided, destroyed, or converted to any other type of atom
* Atoms of different elements combine in simple whole-number ratios to produce compounds (stable combinations of atoms)
* Atoms of different elements have different properties
* Atoms of a particular element have unique properties
* Chemical change involves joining, separating, or rearranging atoms
*Atoms of a particular element have unique properties
identical properties**
John Dalton’s Model
Solid Sphere Model (empty space)
empty siya kasi he has a ton of problem
Theorist
His theory stated that atoms are indivisible, those of a given element are identical, and compounds are combinations of different types of atoms.
Dalton
Model
Atoms aren’t indivisible - they’re composed from subatomic particles.
Solid Sphere (1803)
Model
Recognised that atoms of a particular element differ from other elements.
Solid Sphere Model
J. J. Thomson’s Model
Plum Pudding Model
si thomson naginvent ng sugar malay q teh
sugar plum increase blood sugar kaya puro positive lang
He discovered electrons (which he called ‘corpuscles’) in atoms in 1897, for which he won a Nobel Prize.
Thomson
Model
No nucleus, and didn’t explain later experimental observations.
plum pudding
Model
It shows the atom as composed of electrons scattered throughout a spherical cloud of positive charge.
Plum Pudding
Who’s model is the Nuclear (1911)?
Ernest Rutherford
Theorist and Model
He fired positively charged alpha particles at a thin sheet of gold foil. Most passed through with little deflection, but some deflected at large angles. This was only possible if the atom was mostly empty space, with the positive charge concentrated in the centre: the nucleus.
Nuclear by Ernest
Model
Realised that positive charge was localised in the nucleus of an atom.
nuclear
<Model
Did not explain why electrons remain in orbit around the nucleus.
Nuclear
He modified Rutherford’s model of the atom by stating that electrons moved around the nucleus in orbits of fixed sizes and energies.
BOhr
bored siya kaya minodify niya, stationary pa siya kasi fixed
Model
Electron energy in this model was quantised; electrons could not occupy values of energy between the fixed energy levels.
planetary model
Bohr’s Model
Planetary
Model
Proposed stable electron orbits; explained the emission spectra of some elements.
Planetary
Model
Moving electrons should emit energy and collapse into the nucleus; model did not work well for heavier atoms.
Planetary
he was not able to explain
how electrons are moving outside the
nucleus because these electrons does
not have a fixed position.
Model and theorists
According to him, they only have orbits but was not
able to explain that these type of
model does not work at larger in terms
of the shell and energy levels. He was
only able to explain smaller atoms
Bohr’s planetary
Who created the quantum model
Erwin Schrodinger
Model
electrons do not move in set paths around the nucleus, but in waves.
quantum
model
It is impossible to know the exact location of the electrons; instead, we have ‘clouds of probability’ called orbitals, in which we are more likely to find an electron.
quantum
Model
Shows electrons don’t move around the nucleus in orbits, but in clouds where their position is uncertain.
Quantum
Model
TOF. Planetary model is still widely accepted as the most accurate model of the atom.
F (quantum)
whose evidences
- bombarded Beryllium with alpha particles from the natural radioactive decay of Polonium
- concluded that the unusually penetrating radiation consisted of uncharged particles having (approximately) the same mass as a protons
James Chadwick
model
limitation is he doesn’t
mention the momentum of the
electrons
quantum
independent developed the precurosr to oyr modern periodic table
dmitri mendeleev and lothar meyer
Principle
it is impossible to measure accurately both position and momentum of a variable simultaneously.
Heisenberg Uncertainty
when you get the position of electrons, you don’t
get the momentum vice versa.
Principle
helps determine electron configuration
- electron fill the lowest-energy orbital that is available
Aufbau
Principle
each orbital can hold up to
two electrons with their spins
in opposite directions (paired)
Pauli’s Exclusion
Principle
each orbital in a subshell is half-filled (with one electron) before any orbital becomes completely filled (with two electrons)
Hund’s Rule
