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Problems with bohr, quantum mechanics, electron configuration, periods, groups, trends UNIT TEST 2 CHEM

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hasanahatesscience's version from 2016-10-20 23:49

Problems with Bohr (shell) Concept

Question Answer
Bohrs Model successfully explainedthe line spectrum of hydrogen (1e)
As the number of electrons increasedhis model could not explain their line spectrum.
Sub energy levelswere thought to exist.
Scientist in the 1920s suggested that the electron could not be visualized as adiscrete particle moving in some type of orbit around the nucleus.
It was necessary to think in the terms of the chance of finding the electronsin certain spaces around the nucleus (orbitals)
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Quantum Mechanics

Question Answer
What did Quantum Mechanics do?Successfully explains the line spectra of all elements.
The fundamental concept isunlike charges attract and like charges repel.
+1- attract -1-repel
Therefore, electrons will always be attracted towards the nucleus (positive attractive force)be repelled by each other causing them to be in different spaces around nucleus.
In order to minimize repulsions between electronsthe distance between the orbitals growed/maximized.
Quantum mechanics describes the location and behavior of electronsin any atom BASED ON QUANTUM NUMBER.
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The Principal Quantum Number "n"

Question Answer
Tells us how far the electrons arefrom the nucleus
It can be any whole numberand replaces the shell notation
Electrons in first shell have a positive quantum number of 1second has a pqn of 2
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The Orbital Quantum Number

Question Answer
Describes the shapeof the electrons orbitals
They exist b/c electrons repel each other andare attached to positive nucleus
They seek to minimize repulsionsand maximize distance between them
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4 types of orbital shapes

Question Answer
S orbitalsspherical shape
P orbtialshave infinity sign/dumbell shape
D orbitalshave complex shapes
F orbitalshave even more complex shapes
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The magnetic quantum number

Question Answer
The orientation of the electron orbitalsin the presence of a magnetic field.
In any energy level there can be1s orbital, 3p orbitals, 5d orbitals, 7f orbitals
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The spin quantum number

Question Answer
The electrons is a small negative particlespinning on its axis creating magnetic field
There are 2 spinning motionsclockwise (magnetic field pointing NORTH) and counterclockwise (south)
Unlike magnetic fields attract to each other (+,-)can overcome negative repulsions and lead to electrons pairing off in orbitals
AN ORBITAL CAN CARRY0,1 or 2 ELECTRONS
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Electron configuration

Question Answer
Electronic configuration of an element provides us with adescription of the arrangement of the electrons in the atoms of that element
There are 2 principles in understanding how electrons are arranged1.NUCLEUS IS POSITIVE SO ELECTRONS ATTRAC TO IT (lower energy shells are filled first) 2.ELECTRONS ARE NEGATIVE SO THEY REPEL EACH OTHER (limits # of electrons that can be in any region)
To summarizeElectrons are attracted to nucleus. GREATER NUMBER OF PROTONS IN NUCLEUS GREATER THE POSITIVE ATTRACTIONS FOR ELECTRONS. Electrons repel each other within an energy level. Sideways repulsions from s,p,d and f orbitals. this determines number of electrons that can be in any shell.
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Periodic Table

Question Answer
PERIODIC LAWIf elements are arranged in order of increasing atomic number a pattern can be seen in which similar properities occur
GroupsThe vertical columns on the periodic table (chemical families).
Groups includeelements with similar properties
Groups have iupac/numbering systemGroups 1-18
Groups had an old labelling systemRoman numerals with letters a and b
Groups includes elementswith simular properties
Elements in a grouphave same number of electrons in out most shell/orbit
Electrons in outermost shell are calledvalence electrons
Periodsare the horizontal rows in the periodic table
Period numbering system1,2,3,7 (from top to bottom of table)
Each period representsan electron shell or orbit
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Metals, Non Metals, and Metalloids

Question Answer
Representative elementsare the groups with roman numerals
Transition elementsare the groups with roman numerals
Inner transition elements are theLANTHANIDES (ATOMIC NUMBER 57-70) and the ACTINIDES (ATOMIC NUMBER 89-102)
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Chemical Groups (families)

Question Answer
Alkali MetalsGroup 1, soft, VERY REACTIVE stored under oil to prevent them from reacting with oxygen in air, oxides and hydroxides dissolve in water to give alkaline solutions, form with ions with single charge, react with some non metals to from white salts *(sodium chloride). have low melting points, low boiling points and low densities
Alkaline Earth MetalsGroup 2, react with water, not as reactive as group 1, found in nature
HalogensGroup 17, poisonous with strong smell, froms molecules of 2 atoms, reacts with metals to form salts (NaCL, Li, L) Halogen ions have single negative charge
Noble GasesGroup 18, low melting points , stable, full valence shell, exist as single atoms
Transition Metalscentre blcok of PT, hard and dense, good conducters, form coloured ions and compounds, form alloys with other metals
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Trends in the Periodic Table/Atomic Radius

Question Answer
Atomic Radiusradius of atom, atoms volume
DECREASES WHEN YOU GO LEFT TO RIGHT BECAUSENucleus of atom GAINS PROTONS INCREASING POSITIVE CHARGE and attractive force between oppositive charges in nucleus become STRONGER
INCREASE WHEN YOU GO DOWN A GROUPenergy level increases
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Trends in Pt/Ionization Energy

Question Answer
AMOUNT OF ENERGY NEEDED TO REMOVE OUTER MOST ELECTRONSAGINST ATTRACTIVE FORCE OF NUCLEUS
INCREASES WHEN YOU GO RIGHT OT LEFTBECAUSE ELEMENTS ON RIGHT WANT TO TAKE OTHER ATOMS ELECTRONS TO BECOME STABLE
DECREASES WHEN YOU GO DOWN A GROUPB/c ELECTRONS ARE FURTHER FROM NUCLEUS MAKING IT EASIER TO REMOVE
Measured inKj/mol
Requires more energy tolose than gain
Easy to remove ooutermost electrons from those atoms that havemany electrons (elements near bottom of the pt)
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Trends in Pt/Electronegativity

Question Answer
This is the atoms desire to grabanother atoms electrons (give away theirs)
INCREASES AS YOU MOVELEFT TO RIGHT BC IT IS EASIER TO GIVE AWAY THAN TAKE THEM
DECREASESAS YOU GO DOWN A GROUP (atomic number increases)
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Trends in the Pt/ Electron Affinity

Question Answer
MEASURES THE CHANGE IN ENERGY THAT OCCURS WHENAN ELECTRON IS ADDED TO THE OUTER ENERGY LEVEL OF AN ATOM TO FORM NEGATIVE ION
INCREASES AS YOU MOVELEFT TO RIGHT
DECREASES AS YOU GO DOWN A GROUPFIRST ELECTRON AFFINITIES BECOME LESS
HIGH NEGATIVE NUMBERS MEAN A HIGH ELECTRON AFFINITYLOW NEGATIVE NUMBERS MEAN A LOW ELECTRON AFFINITY
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