Atomic Structure Flashcards
who proposed the idea of an elements. when
In 1661 robert boyle suggested there are substances that cannot be made simpler- elements
who suggested elements were made of atoms. when?
John dalton in 1803
who discovered the electron and in what year
JJ Thompson in 1987. He then created the plum pudding model.
Who discovered the nucleus. How and when.
Rutherford in 1911 by throwing alpha particles at a gold foil scattered backwards due to the positive charge
Give the relative mass of each sub-atomic partical
proton- 1
electron- 1/1840
neutron- 1
how do you work out the number of neutrons in an atom
atomic number - proton number
what is an isotope
elements with the same number of protons but differing numbers if neutrons
who proposed the solar system model- nucleus orbited by electrons in shells
Bhor in 1913
who discovered the neutron
James chadwick in 1932
how many electrons can each shell hold
1st - 2
2nd- 8
3rd- 18
define relative atomic mass
the average mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12.
how do you work out relative atomic mass
average mass of 1 atom divided by mass of one c12 atom
what does a mass spec machine do
determines the mass of a substance in order to identify it.
what happens in electrospray ionisation
dissolved in a volatile substance and pushed through a fine needle connected to a positive terminal with high voltage supply, producing positively charged droplets as they gain a proton from the solution
what occurs in electron impact ionisation
high energy electrons are launched at a vaporised solution, knocking an electron off from each particle leaving us with positive ions
what happens inside a mass spec machine
Acceleration - positive ions move towards the negatively charged plate. Lighter ions move faster
Ion drift- ions pass through a hole in the negatively charged plate into the flight tube
detection - ions with the same charge reach the detector at the same tie as they have the same velocity. They hit a negitively charged plate creating a current. Flight time is calculated.
what is an atomic orbital
a region around a nucleus that can hold up to two electrons with opposite spins ( one up one down)
what is an energy level
an electron shell.
what is an electron
a negative cloud of energy that takes the shape of the orbital it is in
what are the types of electron orbital
s,p,d,f
what does an s orbital look like
spherical
what does a p orbital look like
a bell shape. 3 of them.
whats a sub level
all of the orbitals of the same type in the same shell
what are the rules for assigning electrons to atomic orbitals
- each orbital can only contain 2 electrons
- lower energy levels filled first (1s,2s,2p,3s,3p,4s,3d,4p,4d,4f)
- atomic orbitals of same energy level fill singly before pairing (bus example)
define first ionisation energy
the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms
what happens to ionisation energy across a period
generally increases, as charge increases and shielding remains the same making it harder to remove. It decreases at group 3 because the outer electron is in a higher energy level, so less needed to remove it. It decreases at 5 as the p orbitals begin to pair up, making it easier to remove an electron due to pair repulsion
what happens to first ionisation energy down a group
generally decreases atomic radius/shielding increases
