1 Atomic structure DONE Flashcards
(23 cards)
What is the plum pudding model?
-sphere of positive charge
-small negative charge distributed within
What is the current atomic structure model?
-Electron Shell Model
-small dense central nucleus
-surrounded by orbiting electron in SHELLS
How can you calculate max number of electrons in a shell?
-2(n^2)
-n being the shell number
What is Relative atomic mass(Ar)?
-average mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12
What is an isotope?
-atoms of the same element with the same atomic number (protons) but different number of neutrons.
How are isotopes diffrent from the element ?
-differ in mass and therefore in physical properties
What does a Mass Spectrometer identify?
analytical technique which identifys
-mass number
-abundance of isotopes
What is Time of Flight Mass Spectrometry?
-TOF records time taken for ions of each isotope to reach a detector
-shows each isotope present ions a sample
What are the stages to Time of Flight (TOF) Mass Spectrometry?
-Vacuum
-Ionisation
-Acceleration
-Ion Drift
-Detection
-Data Analysis
Why do isotopes react in the same way?
same electronic configuration
Why is a mass spectrum in a vacuum ?
-prevents ions colliding with any particles
How is ionisation done in mass spectrometery?
-sample dissolved in volatile solvent
-forced through fine hollow needles which are connected to the positive terminal of high voltage pack
-produces positive charge droplets (lost electrons to voltage supply)
-solvent evaporates until only a single positive charged ion remains
What happens in the acceleration step of mass spectrometery?
-positive ions accelerate to a negatively charged plate
-lighter ions achieve higher speed
What happens in the ion drift step of mass spectrometery?
-ions pass through hole in plate
-forms beam to detector called flight tube
How is a current formed at the detection plate in mass spectormetery?
-ions with the same charge meet detector
-flight times are recorded
-positive ions pick up an electron from detector
What do peaks of a mass spectrum show?
relative abundance of each isotope
What is low and high resolution mass spectometery?
-high has 5 dp
-low is 1 dp
What are the sublevels?
-s, circular shape ,1 orbital in a sublevel,holds 2 electrons
-p, infinity shape, 3 orbitals in a sublevel, holds 6 electrons
-d, four clover shape, 5 orbitals in a sub sublevel, holds 10 electrons
-f, 7 orbitals in sublevel , holds 14 electrons
Why is 4s orbital filled before 3d?
4s subshell has lower energy than 3d.
Two electron in the same orbital must have opposite …
-spins
-which are represented by arrows
What is Ionisation Energy (IE)?
-IE is the energy required to remove a mole of electrons from a mole of atoms in the gaseous state
-in KJmol-1
e.g.
Na(g)–> Na(g)+e-
What are the trends in first IE across a period?
-increase across a period
-nuclear charge is increasing so electron is harder to remove
What are the trends in IE down a group?
-decrease as you go down a group
-outer electron gets further away from the nucleus
