Chapter 5 Electrons And Bonding Flashcards
What are electron shells?
- regarded as energy levels that increase as the PRINCIPLE QUANTUM NUMBER INCREASES!
- made up of atomic orbitals
WHAT IS AN ATOMIC ORBITAL
- A REGION IN THE ELECTRON SHELL THAT CAN HOLD UP TO TWO ELECTRONS WITH OPPOSITE SPIN!!!
- it is a region of space where there is a high probability of finding an electron
What is true for all atom orbitals ?
- there are always 2 electrons in any orbital, no matter it being spd or f
They have different shapes
How is the layout of atomic structure actaully like for electrons?
Electrons are contained in different shells which are energy levels
- in different shells are different sub shells, like an s sub shell , p sub shell
- each Sub shell contains all the orbitals of that type in it
So an s sub shell contains s orbitals, and 1 s orbital
A p sub shell will contain only p orbitals and 3 p orbitals each
These all hold max 2 electrons of opposite spin
Goes in order 1 3 5 7 etc
And the amount of sub shells increase with each quantum number
What are the features of an s orbital
- shape
- size
- shape is a sphere
- the greater the quantum number, the GREATER THE RADIUS OF S ORBITAL
Features of a P orbital ?
- shape
- what TYPES
- greater the quantum level?
- the shape of a P orbital (electron density ) is in a dumbbell shape
- these can be present in three different axis, so you have px py and pz orbitals
- the greater the principle quantum level, the FURTHER THE P ORBITAL IS FROM THE NUCLEUS
(Hold two electrons again)
How do orbitals fill electrons and why is ther a difference?
Orbitals fill in terms of increasing energy , but each orbital of same sub shell has same energy
- as each new sub shell has higher amount of energy it will go in that order,
- however 3d sub shell has a higher energy level than the 4s sub shell of the 4th principle quantum level
=THUS THE 4S SUBSHELL WILL FILL ITS ELECTRONS FIRST THRN 3D ANF THEN 4P
What is spin and how do we represent the repulsion of electrons
Spin?
- as electrons are negatively charged, they will repel each other
- electrons also have a property called SPIN, this is either up or down
- to show COUNTER repulsion, ELECTRONS MUST HAVE OPPOSITE SPIN
we draw arrow opposite spin in a box
-this also means we don’t have to draw each orbital shape = simplified
What do you have to remember about filling arrows in box and why?
As each sub shell orbital had same amount of energy it doesn’t matter where the electron goes in each orbital
- to INCREASE STABILITY reduce and potential repulsion, each orbital will contain ONE ELECTRON AND THUS ARROW FIRST, before any others are filled with two!
= this makes it MORE STABLE!!
How to do shorthand electron configuration?
- take the NEAREST GROUP 0 NOBLE GAS
and then represent the rest of the configuration omitting the noble gas electron
How can you arrange the periodic table in blocks to do with electron configuration figuration and why? What are they
- based in the last WHERE THE HIGHEST ENERGY SUBSHELL IS (last SUBSHELL)
Left block of two groups = s SUBSHELL has highest energy so S BLOCK - middle 10 = D BLOCK
- right block of 6 = P block
For forming ions what do you have to remember about electron configuration!!!
About 4s and energy levels
- what happens when 4s is filled in terms of energy?
Order!
- filled up in order of energy levels
- AS 4S SUB Orbitals HAS LESS ENERGY THAN 3D, IT WILL FILL UP WITH ELECTRONS FIRST, -
- but then once filled up it has more energy than 3d, so it will lose ALSO LOSE ELECTRONS FIRST
Write in order!
How to represent electron configuration ions and oxidation state again
SUPER SCRIPT FOR ELECTRON CONFIGURATION
- IONS IS 2- 4+ NOT +4
- OXIDATIONS IS +4
WHAT EXCEPTIONS DO YOU NEED TO REMEMBER
What happens and why?
CHROMIUM AND COPPER
- chromium is 3D5
- copper is 3D10
- One electron from 4s sub shell is given to the d SUBSHELL orbital and third makes it MORE STABLE OVERALL (atleast Esch orbital has one electron / full)
REMEMBER CHROMOUM EXCEPTION?
4s1 3d5 (Esch orbital has an electron instead of one do orbital missing one)
Remember COPPER EXCEPTION?
4s1 3D10 (Esch orbital is full instead of one not being full)
PLEASE REMEMBER CHROMIUM SND COPPER CONFIG!
PLEASE
What is an ionic bond
An electrostatic attraction between two oppositely charged IONS
- which are formed by the transfer of electrons from one atom to another
How to show dot and cross?
First show how there were before, and arrow from electrons
2) then SQAURE BRACKETS WITH CHARGE AND OTHER SHELL
- DONT NEED TI ACTUALLY DRAW AN OUTER SHELL THO
What happens to radius of cations vs anions when ions are formed !!remember!!
When losing or gaining electrons, the radius changes respectively
- losing electrons (cations ) = DECREASE IN RADIUS
- increasing electrons (anions) = INCREASE OF RADIUS
What is the structure of ionic compounds as a result of attraction
- ## as they attract In all directions, they produce A GIANT IONIC LATTICE with billions of ions
Properties of ionic compounds
- high boiling and melting points (due to ionic bonds being very strong)
- can be soluble in water or OTHER POLAR SOLVENTS
- can conduct electricity
- is HARD + BRITTLE
Why do melting snd boiling points differ (2 REASONS)
- the bigger the atom, the weaker the attraction , so smaller ions = LARGER ATTRACTION = HIGHER MELTING
- BUT ALSO the larger the charge OVERALL (count all charges up excluding symbol and how many atoms there are ) = HIGHER ATTRACTION = HIGHER BOILING
How to determine if one ionic compound has bigger charge
Exclude balanced numbers , take all individual atoms charge and add up excluding symbol and which ever largest largest
Why are ionic compounds soluble in polar solvents like water?
When are they less soluble / not ?
What is required for an ionic compound to be dissolved?
- ionic compounds dissolve in polar solvents as polar solvent break the lattice down and surrounds the ions, attracting them, forming ion - dipole interactions
2) however if the attraction of the ion is too much, due to the charge , then the attraction could be too much for the water to break the lattice down, making it LESS SOLUBLE
- for example, CaCl2 will be much less soluble because greater charge than NaCl which will be way more soluble as less charge so easier to break down
3) for an ionic compound to dissolve the
- LATTICE HAD TO BE BROKEN DOWN
- THE water must surround and attract ions
- if it can’t then it won’t work
When and why can an ionic compound conduct electricity
- an electric current is just the movement of charge carriers over time. Thus ions carrying charge if free can curry current
- In the solid state ions not free to ,I’ve as held too tightly in place, so can’t, making them INSULATORS
- in liquid state (molten) or aqueous , they are free to move so they can carry current
What is a covalent bond
When does it occur
A strong electrostatic attraction between positive BOTH nuclei and the shared pair of electrons
- when two orbitals overlap
What are structures of covalent molecules? Why
1) as covalent bond attraction is localised, simple covalent structures are made
2) giant covalent if covalent like SiO2 is everywhere
What tends to have a triple bond (what group)
Group 5
What about boron, what can it do and why is this special
Only can make 3 covalent bonds and does, such as boron trifluroide
- OCTET RULE GONE NOW, DONT NEED OUTER SHELL
What is unusual about carbon monoxide “? Remember it’s structure
Triple bond + one DATIVE!
- Leaving lone pair on both atoms
WHEN CAN YOU MAKE MORE THEN 8 ELECTRONS (18) and what us the rule for this
As long as n= 3 (d block) this is fine, but you can’t just have a SINGLE ELECTRON BEHIND, has to be either lone pair or covalent bond
So for chlorine phosphorus and sulfur this happens
What is a / dative bond AND WHAT ORHER NAME?
How do you show
Co ordinate
2) a shared pair of electrons that have been supplied by only one of the atoms, electrons haired but both came from one atom , a lone pair
- you show by doing an arrow head and that shows
